Early Music Blog

CD basses installed on theorbo/Chitarrone: why do they sometime break on the 5th?

Why do CD basses installed on theorbo/Chitarrone sometime break (mostly on the 5th course), even if there are no sharp edges and they were installed properly?


Tiorba (1882)
Source: Biblioteca de la Facultad de Derecho y Ciencias del Trabajo Universidad de Sevilla / CC BY (https://creativecommons.org/licenses/by/2.0)

The CD strings (from 110 CD up to 220 CD) are designed for renaissance & d minor Lute basses only .
For the long diapasons of medium extensions, the CDL type strings are available.
The thinner CD strings (82 CD up to 105 CD) instead, are designed for 5th courses and octaves for the very lower bass strings of renaissance & d minor lutes.

On theorbo/chitarrone these rules sometime do not work: why?

While on the traditional lute/archlute the 1st string works with the higher FL product (220-230 Hz.m), any kind of theorbo/chitarrone works with an exceptional, longer vibrating string length, far longer than what was calculated for lute, hence the fact that the 1st and 2nd strings are forced to be tuned an octave lower. For example, while a renaissance lute tuned in A at modern pitch has a scale around 57 cm, a theorbo in A at the same standard pitch has a scale of 85-88 cm (the FL product of the 3rd string b note -that actually is the canterelle- is 220 Hz.m)
In these conditions, the range of the FL products typical of a 5th course of a renaissance Lute (79-81 Hz.m) or the 6th course of a d minor lute (71-74 Hz.m) allows the use of CD strings of the thinner range with no problems, while on a theorbo instead, the FL product raises up to 109-115 Hz-m, and it is too high for strings designed as basses.
In practice, the FL product of a 5th course on a theorbo is the same of a 4th course on a renaissance lute.
This is the explanation of why a CD string installed on the 5th course of a theorbo can sometimes break: the FL product is too high (it’s not a matter of tension; tension has no influence in the FL product).

In conclusion, the proper place for the CD strings is - in the higher position - the 5th course of the renaissance lute, or the 6th , 7th  and 8th fretted theorbo basses. For the 5th course of a theorbo/chitarrone, the right strings to use are NNG or CDL type.


Vivi felice




The Italian method of making strings from whole unsplit lamb gut: story of a rediscovery

The Italian method of making strings from whole unsplit lamb gut: story of a rediscovery



by Mimmo Peruffo

Download PDF version

1) Foreword

For what I know, it was probably only in the 1970s that the research on the gut strings of the past became popular. Before then, this problem doesn’t seem to have emerged yet, both because everyone was mainly addressed to the performance practice, and because the gut strings that were generally available at that times did their duty nonetheless: nobody could imagine that strings could have been made differently in the past, and no accurate documentation regarding the ‘historical’ diameters was available.

It was generally believed that the sounds of bowed instruments in the past had to be feeble, and that the string diameters had to be very thin, even if there was no supporting documentation.

Starting from the 1970s, however, as the research delved into the subject of historical performance and instruments, new attention began to be paid to the issue of the strings: in fact, new documentation regarding the average diameters of strings and the settings used in past centuries began to be discovered; moreover, the most famous areas of string production were brought to light, together with the names by which the various types of strings were called (Catlins, Lyons, Pistoys, Minikins, Gansars etc.), and finally new assumptions were introduced that led to related discussions, principally regarding the strings in the low range (loaded strings, roped, etc.).

Thanks to this newly found documentation, it began to be understood that the diameters of the strings used on bowed instruments in the past were not generally as thin as people thought, and therefore modern strings could not meet the acoustic standards required by the restored settings of the past. For example, it was impossible to employ a third string in pure gut on the violin or on the cello; similarly, there was no way to use gut basses on the family of the viola da gamba or on the lutes. Modern string were too stiff, therefore they were difficult to play under the bow and gave poor acoustic performances.

In those years, several articles were written starting to describe the historical productive cycle used in the past, mainly referring to Italy and France of the second half of the 18th  century, when the Age of Enlightenment finally began to emerge (information from previous centuries is in fact very incomplete or scarce).

The period from the 1970s to today has also been marked by some changes in the manufacture of modern gut strings, as a result of discoveries of new historical documentation, and more recently we are witnessing the appearance of amateur string-makers.

2) My experience

I began my research in mid 1980s as a simple enthusiast, spending about ten years working on the problem of Lute gut basses, developing theories, doing practical tests at a string-making company, and finally accurately measuring the holes of the original lute bridges in museums.

To learn more “The theory of loaded gut”
To learn more “Why the loading of gut for lute bass strings is the only hypothesis that fulfils the requirements of seven criteria arising from a consideration of historical evidence”

I then moved on in my research on musical strings, starting to look for documentation in european libraries, state archives, museums of musical instruments and private collections (including works by other scholars), and managed to collect a fair amount of historical documentation (which, for the most part, I have not yet had time to publish) along with a few hundred measurements made on samples of gut and wound strings, that I simply call ‘ancient’, found on musical instruments in museums (especially on not yet restored instruments) for which I always released a report and calculations to the museum.

Survey card example
Survey card example

My profession as a string-maker derives from all that was handed down to me between 1991 and 1992 by Arturo Granata, a professional string-maker that, if I recall correctly, worked for 30 years in Savarez before coming to Italy, where he introduced a lot of modern string-making technology and other novelties in the Italian string-making industry that was still hanging most of the old methods, and he started his own string-making company near to Milan, aimed at the industrial manufacture of musical, tennis and surgical strings, using modern techniques (stiff and transparent strings, similar to Nylon).

Arturo Granata and me

However, what was passed down to me was mainly focused on how to produce strings in the “modern way” (beef gut serosa, modern chemical process, constant use of hardening salts, centerless grinding machine, very stiff strings).

The documentation found by me and by others, the old strings found in museums, and my background as a chemist, allowed me, at a certain point, to introduce some technological changes in order to make gut strings more relevant to the historical procedures, without sacrificing the advantages of the modern method (speed, quantity and reliability). The strings that are now produced are much more elastic (i.e. high twist; no hardening salts). I still based my production on the use of beef serosa strands but I sometimes passed indifferently to those of sheep (I do not find any appreciable differences, when using strands).

Finally, I changed the way I rectified the strings: I no longer bring them to the smoothness level typical of modern stringmaking, but I keep them partially polished: this idea came to my mind after having touched and measured the Paganini strings, handled hundreds of old strings, and having discovered some written sources.

Paganini 1st violin string (.71 mm) Genoa 2004


Giuseppe Antonelli, Venezia, Nuovo dizionario universale 1846: the violin 1st string must be not polished


These changes finally allowed us to install without any problem a third string in pure gut on the violin and on the cello; historical diameters could finally be proposed and, as a result, the acoustic performance of an orchestral ensemble began to change for the better.

This was not an easy transition: when I started, the average diameter used for the first string of a violin was a stiff .52-.54 mm: in this conditions it was not possible to switch abruptly to a string with a diameter of .66-.68 mm – as recovered from historical sources and findings – because of the resistance of musicians, but above all of the luthiers. At the same time, some instruments could not physically support larger diameters (in general, the problem was that the angle formed by the strings on the bridge was too sharp so the pressure on the soundboard was actually too much).

Therefore, I decided to increase the diameter of the strings we offered year after year, making sure to start from the initial 52 mm, and then gradually increasing to 56 … 60 … 62 until we reached the current 64-66 a few years ago. This way, any potential conflict was avoided, and I also noticed that other few string-makers followed the example of increasing the diameters, to the benefit of the overall acoustic quality of the bowed instruments. However, some of them had already introduced the high twist strings in their own process.


At this point, I realized that I possessed:

  1. a considerable amount of historical documentation, both personal and from other researchers,
  2. I had taken several hundred measurements of pieces of old gut strings
  3. I had gained a strong professional experience as a professional string-maker
  4. I  was able to modify  my modern way to make gut strings in a way that was ‘more historical’ (high twist, no hardening salts,  the imitation of the manual polishing etc.)
  5. Thanks to  point 4. we had finally the access to the ‘historical’ thicker gauges, it was possible to install a plain 3rd gut string on violin and cello; the gamba 4th  with a general benefit for the performance


Therefore, I thought it was time to try and recover the manufacturing method that was used in Italy, firstly starting from the comparison between all the sources that described it (and that I could fully understand thanks to my chemical background and direct experience on the field), integrating it with an initiative that proved to be the most decisive lead: filming interviews – including real simulations of the various phases of the productive cycle – with the last elderly string makers in Abruzzo, who were still living in Salle/Musellaro/Bolognano villages, the famous gut string production centers since the middle of the 16th century.

The great fame enjoyed by the strings produced in Italy between the second half of the 16th century and the 1930s is well known: I have often wondered if this was just a fashion or if there were practical motivations instead.


The three fundamental key points to be developed were:

A) recovering the Italian historical productive cycle, comparing all the historical sources that were describing it;
B) recovering the formula for the preparation of the potash or tempra, and its proper use;
C) solve the dilemma of the whole unsplit lamb gut;
D) recover the criteria used in the past when choosing the raw gut.


A) Recovering the historical production cycle used in Italy:


1) comparison between all the historical sources that describe it

2) interviews to retired elderly string-makers of Salle/Musellaro/Bolognano villages (Italy)

Comparison between all the historical sources that describe it

Most of the sources that describe the production cycle of strings were related to Italy and France. Certainly, being a craftsman and chemist (not just a pure researcher) gave me an advantage when comparing all the historical sources that describe it (I also took into account the valuable lists concerning the equipment/tools and ‘chemical’ products reported on the inventories of Roman workshops, found by researcher Patrizio Barbieri, just to see if there were substantial variations/news).

The conclusion was that there’s a substantial alignment between all the sources (with few differences, of little importance), therefore allowing us to finally understand the function of the various phases.

The most reliable sources are certainly those dated after 1760, but also the previous ones, even if brief, have confirmed a substantial alignment (for example, the presence in the shops of the scraping table, the degreasing brass thimbles, the sulphurisation process, the sulphur, the mobile frames, the ashes used to make potash, the twisters or wheels, the shelves to place the bowls, the shades where to dissolve the ashes for the potash, the splash guards for the workers, etc.).

Interviews to retired elderly Abruzzo string-makers

In this work of careful reconstruction, the interviews with several elderly string-makers mostly in the village of Salle in Abruzzo that I was able to film, before their passing, were decisive (some of them were simple workers, but at least a couple of them were owners or Masters).

During these interviews, I was taught in practice the following points:

-How to choose/distinguish  the best sheep/mouton/lamb intestine and how to take out it from the animal’s body;

-How to handle correctly the fermentation’s bath process;
-How to build the scraping table and scraping cane, and how to scrape correctly;
-How to build and use the brass thimble, and how should the various phases be organized and divided;
-How to build and use the splitting horn;
-How to build the mobile frames and why they are better than the long and fixed ones;
-How to make the braided horsehair, what it’s for and how to use it on the strings;
-How to dry the strings on the frames in the proper way;
-How to handle the  sulphurisation process;
-Which is the special hand movements to correctly smoothen the strings (otherwise they might get faulty) together with the materials and tools to be used, and how to choose them;
-When was the centerless grinding machine introduced in Italy, by whom;
-When the transition to beef serosa took place in Italy, together with the related modern chemical processes (French industrial method).

I would like to underline the importance of the fact that all information has been transferred from technician to technician, and most importantly all through practice (to put it short, it was not simply read on a book). Knowledge and craftsmanship is notoriously transmitted through direct apprenticeship and long experience in the workshop: the simple view or description of the scraping cane, or the degreasing brass thimble, found in the old sources will never be able to transmit all the information, not even to an expert industry technician or an academic researcher.

As an example, the scraping cane and the degreasing thimble I had prepared before the visit by carefully examining all the images found on the historical sources, were immediately discarded by the elderly string-makers, telling me that I would never be able to make any string with what I prepared . Even the simple choice of the proper wood to be used for the scraping table must follow precise criteria, handed down from father to son for generations: the fir table I prepared was in fact immediately refused (!)

Scraping process


Thimble rubbing and potash bath


Manual polishing with oliv oil and dryed Equisetum plant

From these interviews, I realized that the method used in Abruzzo since a few decadies ago was fortunately maintained crystallized since the beginning of the 19th century; the technical terms used by these elderly string-makers were often the same found in the historical documents, even on the lists of the inventories of late 16th century. For example, they would say “break” the gut , i.e.‘spaccare le mazze per mezzo’ (just like it was written in the statutes of the string makers of Rome of the late 16th century); they called the twisting machine simply wheel, i.e. “ruota” or “rota”, as in the historical sources; thwe potash was still called ‘Tempra’ etc.

The only differences that were found during these interviews concerned the use of pure potash from chemical process instead from vegetable ashes, and abandoning the whole gut in favor of cutting it into two strips, as was instead traditionally used outside Italy (apparently starting from the end of the 18th century). Only one of these old string-makers, Astro Di Russo (who was the owner), remembered that when he was a child, they still used burned white wine- lees to obtain potash (Savaresse, in the second half of the 19th century, was already using the pure chemically produced potash).

However, no one had ever heard of the use of whole gut, let alone of the strict criteria for selecting the raw material, as copiously described in historical sources.

Moreover, no one was able to tell me anything about the concentration of the basic potash bath: this preparation was in fact only in the hands of the Master or Maestro (the owner). In documents of the 19th century, it is reported that the potash was only prepared by the Master, in a large barrel, mixing it with a pole, and that next to this barrel there was another identical one, filled with pure water only, to be used for the various dilutions during the production cycle.

I found a picture that shows this:


The Maestro with the two barrels and the pole used to mix the potash solution in 1930s (source: La Bella website)

Corderia italiana, 1920’s (courtesy of Daniel Mari, New York):

Thimble rubbing and, at the back, the  gut splitting; on the left the barrels with the potash are visible

Final manual polishing and oiling : note the mobile frames

The sulphuration room 

French string-makers, mid 19th century: the  gut splitting; the  intestine scraping; treatment tank

Tools  (Pinaroli, Rome 1718)


Tools (Pinaroli, Rome 1718)


In conclusion, the only difference between the production cycle in German-speaking countries, and the one in use in Italy, seems to be the use of whole lamb gut; the particular quality of the raw material and perhaps (perhaps) the use of special/different potash baths (from wine lees instead of plant ashes). In fact, there does not seem to be any particular difference in the various phases of the production cycle, except for the fact that sometimes there are fixed frames (typical of the modern stringmaking) instead of mobile frames:

1678 Germany (Wenger)

Diderot 1765 ca   

We can summarise the Abruzzo production cycle as follows:

1) The intestines are collected and manually emptied of the manure directly at local slaughterhouses, as soon as possible after slaughter by the ‘Mazziere’. If the slaughterhouse was not located in the surroundings of the string-making companies, the intestine was emptied, scraped on site, salted and then sent to the string manufacturers in closed barrels;

2) Controlled fermentation: intestines, collected in bundles, are soaked in cold water for a few days in order to start a slight fermentation, that allows an easier scraping action. The duration of the bath depends on the season: 1-2 days in summer; 3-5 days in winter. The water must be changed frequently.

3) Scraping treatment, made by passing over the intestine on a tilted table using a specially designed cane: only the useful membrane remains. This operation removes the useless membranes and the fat, but not completely

4) Passages with the brass thimble: in this phase, each gut in its whole length (20-25 meters) is first left to soak for a period of a few hours up to half a day, in the most diluted solution of potash, and then undergoes a rubbing process using a thimble placed on the index finger agaist the thumb of the ‘Lavorante’; each gut is scraped from four to six times a day (depending on historical sources) and for about eight to ten days. After each day, the concentration of the potash bath is increased until reaching the pure potash (some historical source mentions that the last bath has a double concentration, but there are no substantial differences in the final string; sometime the rubbing process is done in dry conditions i.e. ‘a secco’). The concurrent mechanical abrasive and alkaline action using an increasing concentration, eliminates the last traces of residual fat and submucose, but also modifies the nature of gut, making it suitable for becoming a good string for Music.

5) Gut gauge selection: this operation is extremely important and starts already at the slaughterhouse, but is carried out much more accurately in the string-making company, during a phase that comes immediately before the combination of the intestines, that will be then followed by the twisting, and is called ‘capatura’; the worker is called ‘Capatore’.

6) Twisting: the selected guts are cut in the lenght, in order to obtain the right length for the frame, and then combined together, according to the desired range of diameters of the final string. The general rule adopted in string-making is as follows: for thin strings, small intestine gauges are used; for thick strings, larger intestine gauges are used. The use of high-quality, strong and more expensive lamb gut, purchased and processed in summer months, was reserved only for the most stressed strings: the Violin trebles.

7) First twisting: using the “wheel” or “twister” (by the worker called torcitore), the strings are first twisted on a frame that is firmly placed on a table, that also has space for the bowls, called ‘rinfrescatore’, that are filled with guts. The number of turns varies from source to source, and also depends on the ratio of turns between the wheel and the rotating hooks (they are generally two, sometime just one)

8) Rubbing of the string using a braided horsehair soaked with potash: this treatment is not used to smoothen the string, but to remove the bubbles inside the whole gut by squeezing it, and also to remove most of the water contained/trapped in between the guts, improving the bonding between the fibers. Some documents indicate this as polishing, but it is a misinterpretation

9) Sulphurization: The freshly twisted strings, stretched on the mobile frame, are brought in a hermetically sealed room, with a very wet floor, and treated with  burned sulphur fumes

10) Second twisting (‘ribattitura’): the sulphured strings lose traction, therefore they are then restored by a new twisting action, and then returned into the sulphur room

11) Third and last twisting: the almost dry strings are twisted for the third time and then left to dry completely in open air; the thicker strings are simply twisted by hands

12) Final manual polishing: after being dried in open air, the strings (except violin first strings, that sometimes were excluded, depending on manufacturer and historical source) are polished using a cloth containing pumice powder or a dried abrasive herb called Equisetum, moistened with olive oil. This phase is very critical, and perfect manual skills are required.

13) Oiling: the polished strings are then passed with a cloth soaked in olive oil (Italy) or almond oil (Germany, Austria, England, etc). Siccative oils are never mentioned. In the 19th century some author states that oiling destroys bow-hairs and therefore advises to avoid it (for example: Heron Allen, 1890)

14) Cutting and packaging: starting from the mid-eighteenth century, strings are cut directly from the frame and then packaged in circular coils using a tool called ‘Bussolotto‘; before that time, they preferred the shape of a bunch made with a tool called ‘Forma’, ‘Banco da ingavettare’ or even ‘Forchetta


  • the cores that were then covered with silver or silver-plated copper wires were never subjected to sulphurisation and oil.
  • string makers of the past also produced gut strings for different uses such as: beating cotton; elements for mechanical transmission; for hatters; for watchmakers; for sports use; for whips for horse riding
  • Strings were sometimes coloured with vegetal pigments dissolved in water
  • Rock Alum salt: it is mentioned around 1670 by Skippon during a visit to a Paduan stringmaker; in late 18th century it was also described as an ingredient in French and Italian encyclopedias, explaining that perhaps its possible function was to precipitate the impurities present in the potash derived from plant ashes.
    It was only in the beginning of the XIX century by Labarraque and then second half of the 19th century that the French string maker Savaresse made it clear that the Rock Alum salt was sometimes used to make stiffer gut strings. This salt is now widely used in the modern cycle. We have not used it (it does not appear to be in use in the Abruzzo, Neapolitan and Roman historical stringmaking).


  1. B) The basic potash (also called in Italy in different ways: ‘acqua forte; griepoli; liscia; lescivo; potash, perlash; ranno; tempra’): the reconstruction of the basic formula.


One of the most important elements – if not the most important – concerned the reconstruction of the basic potash preparatory formula: the modern string making company uses different and more complex chemistry. If you do not follow the right chemical steps, the reconstruction of the historical cycle alone does not lead to quality strings (they break, they are stiff even if they are very twisted, the fibers are not well bound together, etc.). There aren’t many historical sources that tried to describe how to prepare it; moreover, being often written by non stringmakers, there’s always a reasonable doubt for errors  maybe intentionally introduced by the stringmakers themselves in order to keep safe their secrets.

A further element of difficulty are the units of measurement used in each Italian small kingdom of those times and the fact that we do not know the percentage content of the potash in the plant ashes used, which ranged from the best product, which were the white wine lees, to the worst in terms of concentration of potash, which were the common ashes of plants properly passed to the gravello/clavello   (i.e. the sieve) called ceneri gravellate (or clavellate). In the nineteenth century the potash was also distinguished by different impurities degree (the best and pure was the so-called Perlassa, but it’s mentioned only starting from the beginning of the nineteenth century). In short, there are many uncertainties.

The comparison of all the sources we have of the late eighteenth century and those of the nineteenth century, however, reserved us a pleasant surprise; the variation in the concentration of the basic potash bath obtained from the calculations considering all the related sources was within a narrow range (+- 15%): we can conclude that the strings production cycle, at least from the mid-eighteenth century, was already highly standardized and continued likewise until 1920’s and that the informations were right.

The detailed analysis of why increasing concentrations of the potash during  the thimble rubbing  is easy to explain (it is a methodology that is also used in certain preparatory steps in modern chemistry): we start with a low concentration of an alkaline agent, which removes the portion of fat that is easier to remove, reserving the maximum concentration of potash for the smallest residual quantity that is more tenacious. The alkaline treatment, however, is not only used to remove the fat: it also alters the structure of the gut making it more elastic, softer and more prone to bindings between the fibers. A string obtained directly from perfectly degreased casing, but without an alkaline treatment, will be stiff, fragile, dry and with weak bond between the fibers of the gut string.

Wine lees


Burned whine lees- ashes


C) The whole unsplit gut

In the Italian production cycle of the XVI, XVII, XVIII and XIX centuries, the animals whose intestines were commonly used in the string-making industry were both goat (mainly in Naples) and sheep intestines (in the eighteenth century: 7-8 months lambs, middle-age lambs up to the adult sheeps. It is also frequently mentioned ram and wether).

In the slaughterhouses they used to treat any animal, always for alimentary reasons only; it was then up to the string-maker to select the intestines  (coming from different sources and sometimes from very far away) according to their gauges, following the rule, that we have come to know, that the stronger guts of smaller gauges (more expensive) had to be used only for the thinnest strings (Violin 1st only), and vice versa.

The common situation that is found in many Italian documents of the XVIII and XIX century is that with three or four whole guts you should get the range of diameters typical of the Violin 1st string (diameter of  .65-.73 mm, approximately summarizing the historical sources): the starting intestines must therefore have been very thin. In some cases it was possible to make the diameters mentioned above also with 4 guts: in this case the cost of the product was higher (in exchange you had a greater stenght, gauge eveness and longer life time)

Typical gaussian curve concerning the violin 1st string production


 De Lalande, 1765 Paris: violin 1st = 3 whole guts

The use of whole guts was therefore the rule in those countries (such as Spain, Portugal and Italy) where there was availability of small animals that allowed the use of three, sometimes four of their coupled and twisted guts, to obtain the range of diameters suitable  for the Violin 1st string.

In other countries (France, Austria, Germany, etc.) the situation was quite different: their lambs, either for the breed, the climate or the type of feeding, were larger than those of Italy and Spain, and were never slaughtered at an early age, as opposed to what happened in Italy because those animals were precious for the wool. Because of the thicker intestine gauge, it was impossible to obtain the suitable diameters for the Violin first string (was mentioned: 3 whole guts = .90 mm!): this is the main reason for the huge orders of Lute and Violin first strings addressed to Rome and then to Naples by the various European nations in the XVII, XVIII and XIX centuries. There are several documents from the XVIII and XIX centuries, especially from France, which tried to analyze well the situation and conclude that, because of their type of lambs and moutons, it was impossible to imitate the quality of the Neapolitan first strings.

This type of problem gave origin to the ingenious solution of splitting the intestine lengthwise and halfway in order to obtain thinner strips so as to circumvent the obstacle, a technique that is still used today by virtually all string makers, whether they deal with cow’s casings or sheep’s casings: rom the documents that were found, it would seem that this technique was introduced in Germany only in the late XVIII century (the inventor, a certain Israel Kampfe, even won a prize from the municipality of Vogtland in 1785 and the acceptance of German string makers into the corporation) while its use was actually indirectly known as early as the second half of the XVI century in Italy, at least: in the statutes of the string makers of Rome in 1587, 1591, 1642 and 1678 it was in fact forbidden to make gut strings from intestine bundles that were splitted in the middle along the whole length; i.e. ‘spaccare le mazze per mezzo’ (term still used today by the elderly string makers of Abruzzo), under penalty of heavy fines or even whip and jail and the  expulsion from the roman stringmaker’s corporation for a few generations.

Cover of the roman stringmaker’s statute of 1642


Roman stringmaker’s statute, cap VII, 1642: it is forbidden to spilt the intestine in half

In the statutes of Lisbon string makers of 1679, it was also stated that a string maker who was discovered mixing whole guts with guts cut into strips would be forced to pay a hefty fine:

No artisan shall make a string with sheep guts, nor goat guts. Every string that they make, thin or thick, shall be made of lamb guts. And they shall not make them split (longitudinally). Those who do no such thing will pay one thousand reais, being half for the works in town and the other half for the one who accuses them. And those strings shall be considered false and deceptive, and they’ll all be burned.’

Statutes of Lisbon’s string makers of 1679: it is forbidden to spilt the intestine in half

The production of strings from gut strands and not from unsplit gut is definitely considered in Italy (and Portugal) a serious commercial fraud and many were probably the Italian string makers who acted illegally.

An Italian document from the middle of 1846 states that the use of strips to make strings instead of using the whole gut, is to be considered a fraud and it also explains how to detect it

Giuseppe Antonelli, Venezia: New universal dictionary 1846


But why in Italy (and Portugal, Spain) were so strict against those who split the gut in strands? Wasn’t it an ingenious system to be able to use even the larger and more available sheep’s intestines?

The paradox is that while in Italy this kind of fraud was severely punished, in Germany in the late eighteenth century, the (re)discoverer of the technique of spitting the gut into two distinct strips was rewarded, thus allowing the creation of the cellars for Violin and Mandolin and freeing himself from the yoke of having to import them from Italy. The problem was particularly accused by the French who, at the beginning of the 19th century, commissioned scholars such as Labarraque to understand how. They continued for almost all of the 19th century to discuss this problem then definitively solved on one hand by the Savaresse and with the fall of the Italian stringmakers on the other.


4) The problem of the raw material and the best season to manufacture the strings

Until a few months ago it was commonly believed (by deduction only) that a string made of whole unsplit gut should have the same acoustic properties as one made from strips. Unfortunately, the various attempts made by the various contemporary string makers – including us – to make Violin 1st have always failed: the strings were very uneven and with a rather low breaking point. For the thicker strings, this problem does not really exist, but is well known that stringmaker’s capacity is primarily measured in the mechanical holding of the violin 1st string.

In short, no one has ever succeeded in this task.

The solution to the problem came once again from both the examination of ancient sources and animal biology: since the time of Mersenne (1636) they have been arguing about the breed, type of diet and age of Italian lambs whose guts are used to make strings: all this was not available in northern Europe.

Attanasio Kircher (Rome 1650) deals with this topic in an interesting way and so few others in the course of the 18th and 19th centuries which however often repeat concepts already mentioned by previous authors.  Until a few years ago I thought that this issue was irrelevant (working with gut  strands the problem does not show much) but a thorough investigation lasted a couple of years made me change my mind: living beings are flexible, they adapt to both environmental conditions and food and in the same way their intestines (instead, it is not important if the grass is a little polluted or if the animals takes some medicines). The characteristics described by Mersenne and Kircher and other authors are therefore true.

What instead about the most suitable season for making gut strings?

In Italy it is very clear that the production of strings made in winter is the worst in terms of  string strength compared to those that are made in summer and more specifically between June, July, August, September till early October (i.e. the most suitable months for the Violin 1st strings). Some 19th century sources mention, for example, that Neapolitan stringmakers dedicated the winter season to the manufacture of any kind of string – Violin 2nd  included – except the Violin 1st only, which were exclusively produced between mid-summer and early autumn. John Dowland (1626) also takes up the point about the best season to buy strings; i.e. summer (and Paganini too: August). The explanation is simple: the forage in the dry season in the mountains and arid areas is hard and poor; during the winter the pasture is green with plenty of water: the gut changes depending on the food.


5) Mechanical and acoustic characteristics of unsplit gut strings compared with strings made from strips: conclusions

Our unsplit gut strings are made following the historical method we reconstructed, using the correct chemical procedures, using unsplit lamb gut carefully selected (as we speak of ‘resonance fir’ particularly suitable for soundboards, you could introduce the concept of “resonance gut” suitable for making strings), surface are again smoothed by the centerless grinding machine  but with a still slightly rough surface (even if we know  very well the manual polishing process):  nowadays it is totally impossible to carry out again the polishing manual process because of costs, waiting times, risk of false strings but above all for the impossibility to guarantee the scaling of the diameters as today is commonly in use.

These factors have shown a completely different reality from what has been theoretically assumed (i.e. invariance compared to the gut strings made from strips): strings of this type have greater acoustic performance, quickly reach a stable tuning, are more resistant to traction and also much more stable to climate change than homologues made from strips. Finally, there are no tension decreases over time.

These results are remarkable considering that we have not yet experimented the treatment of whitening by sulphurisation (from the mid-nineteenth century some of the well renowned  Paduan stringmakers omitted it).

These evidences would definitively explain why the strings produced in Italy enjoyed the reputation that has always been celebrated in European documents from the late sixteenth to the first half of the twentieth century. Explain exhaustively also why they checked so carefully that the Italian string makers did not do fraud.

We asked ourselves what the reason for this better sound, stability and mechanical resistance is: if we make two identical strings from the same gut (but one obtained from strips) we get quite different results, both mechanically and acoustically.

A possible explanation is linked to the natural conformation of the intestine, which has a sort of robust and thin longitudinal ‘lace’ on which anchors the thin and delicate ‘tubing’ of the intestine.

During the twisting phase it spreads around the lace which results in traction at its ends to create a hypothetical coated string whose core is the ‘lace’.

Vivi felice

Bow instruments: why do we propose two types of sets (Standard and Historical)?

The research on string diameters used in the past is a relatively recent discipline compared to the rediscovery of repertoires played today with original instruments or copies / hybrids.

Until a few years ago it was – and it is still valid today – in fact commonly believed that the diameters used in the past were quite thin. The instruments dedicated to ancient music are therefore for the most part still calibrated according to this type of diameters. In particular, the angle formed by the strings on the bridge is in many cases rather acute, very similar to those of modern stringed instruments.

Baroque Violin

The adoption of truly historic calibres on this type of instrument – which are the majority – would have led to serious problems in the quality of the sound produced and in the ease of emission.

We have therefore decided to make our string frames in this way: on the one hand, by proposing (in the light, medium heavy tension degrees) those series of traditional diameters – even if not historically documented – that are generally adopted today, and on the other hand, by proposing frames that refer to the historical information that has survived, while at the same time making it clear which modifications are necessary in order to have access to these types of gauges that make the instrument certainly richer, easier to issue, of stable intonation and with a longer duration of the strings (as well as being in line with the historically documented criteria).

Vivi Felice

Which are the so called 'secrets' that are important in the 'historical' and 'modern way' to make gut string?

1) Chemical baths

This is the bigger ‘secret’ and clearly takes the first position. The composition of the chemical baths is (and was)  always the very well-preserved secret of the stringmakers of the past and those of today. For example: we can do a lot of video on YouTube showing the whole process to make gut strings but, for sure, we will never tell or shows which are the chemical solutions that we employ, how we manage them and were we use them. Here is the truth: the exact concentration of the product, the different dilutions that are employed during all the process phases, the contact's time and how we 'massage' the raw guts during the chemical treatment are all the most critical parameters on the quality of a gut strings.

At the end of the day, this actually is the very and ultimate secret.

2) The twisting ratio

This is what many already knows but, I say, it is not the most important. There are other things: the drying curve when the strings are on the frame, that it is very different if the weather suddenly change and/or if the strings is made with different quantity of guts. Then it is very important is how much tense are the fresh string just put on the frame and how you 'massage' the strings just after they are on the frame to dry.  It is very important when you add twist to the strings because there are more and more twisting steps, all related to the quantity of gut of the strings, then there is the right interval between the different twisting steps and ... the weather: sometime we went up from the bed at 3 by night because the weather has changed and we must go to the factory and change something in the drying room.

3) The kind of raw gut

It is not the same if the raw gut came from a place instead another one. The medicines, hormones do not influence at all the gut string behaviours (till now this is what we have seen)

4) The cleaning process

It is not important at all if the raw gut was cleaned by machine or by hands: the goal is to obtain a very cleaned muscular membrane.  Both ways are ok.

5) The tools material

It is not important at all that the tools are made in wood like in the past times. It is the same, even better for the tool lifetime, to employ aluminium frames and plastic tools.

6) The kind of frame

It is not the same thing to employ a frame instead another one. the quality of the final string is very different.

7) Number of guts

It is not the same thing if the same gauge is made from 5 thick raw guts or instead from 8 thinner raw guts: the behaviours change drastically.

This is one of the best secrets.

8 ) Gut type

Beef gut or sheep gut: the performance are the same, but at the condition that they were worked in the same way (same chemicals, same twisting ratio etc) and that the sheep gut is cut in strips like the beef gut.  The strings made from whole unsplit lamb gut are, instead, far superior.


If there is not a stringmakers like a teacher and if there is not a lot of daily practice in a string making factory it is not possible to make real, professional gut strings. The chemical process is the background of this job.

Some amateur, nowadays, make a lot of experiments with chemicals with the hope to find the Holly Grail but with gut strings this experimental way unfortunately does not works.

Yes, one can make the string anyway, but they cannot be like those of the past: they  will be very dark (while in the past centuries this was always considered a sign of bad strings) , they will easily breaks and false in the gauge thinner of, more or less, 1 mm; they will have the strips badly bonded together,  they will be stiffer than the equivalent professional strings even if one have twisted them in a  very high twist (a violin and cello 3rd will be dul and hard to play with the bow: unfortunately  the preformers will think that it is not posible to employ a plain gut string) because the chemical process is not the right one.

Here is the deal:  the perfection of the gut string of the past was reached only after centuries and centuries with the continuous support of a lot of smart and clever people that worked hard on the field and were already professionist of this job. Only one that has not a clear vision on the whole situation can thinks that, because he is working hard and with passion (that is itshelf very good), will arrive one day, alone, to discover 'The Way'.

Peculiarities of beef gut

Nowadays, most of the professional stringmakers use beef gut instead of sheep gut. From an historical point of view, the early use of this material dates back to the half of the xviii century but so far we have no evidence of a musical use of it. The industrial production of “serosa” type strings is made possible by machines called “slitting machines” that cut the intestines transforming them into stripes.

Further explanations on the video below:


Essentially, the portion of intestine usually called “runner” which has a diameter of 40 to 50 millimetres and a length of 40 to 45 metres is to be cut in two or three longitudinal stripes starting from the fatless part, meanwhile the remains (around three quarters of all the material) constitute the waste and will serve other purposes.

Sheep gut can instead be kept unsplit or be cut in the middle. The result of the second process consists in two stripes called “beef serosa” which are indeed a kind of “sandwich” made of two membranes: the first one is called layer 1, it has a longitudinal configuration and, consequentially, it is more resistant, the second, and weaker, one is called layer 2 and its fibres are in a diagonal order.

Because of the different shape and consistency of the two layers, their separation becomes necessary and it can be carried out by human personnel or by a specialised Machine. The presence of layer 2 in layer 1 stripes is the main cause of string breakages and unfortunately it cannot be predicted by simply observing them.

Layer 1 serosa type stripes measures are subjected to international standards used on sutures and tennis strings such as 19,16,14,8 mm in width and their length is based on frames used for industrial production of chirurgical threads and tennis (6 to 12 metres)

Later, the stripes form a pack called “bundle”, (made of a hundred strands) which is then salted n order to be preserved and transported.

The use of beef serosa has also brought surprising results:

  • High productivity , quick working process, low manufacturing cost
  • Easy reproducibility of the different batch of strings
  • High resistance to traction

Those advantages allow us to provide our strings to a numerous clientele at a remarkably convenient price, maintaining anyway a certain quality standard, this is a rare peculiarity when talking about sheep gut products. Hypothetically speaking, if string factories ceased to produce beef gut strings, the prices would literally skyrocket because In the past, there were hundreds of these factories, anyway, today the professional ones are just a few.


What about sonority?

It is often claimed that sheep gut stripes have better acoustic performances than their beef gut counterparts, nevertheless there is no scientific evidence of that, meanwhile is ascertained now that unsplit gut is superior to both of them.

The truth is that a string’s acoustic performance depends exclusively on its material’s specific weight and on its elasticity. The specific weight of beef and sheep gut is the same, in fact they are both made of collagen; regarding elasticity, it is dependant only on the way the string is made (and it’s measure is the twisting degree). Another important factor are the chemical processes used in stringmaking, which are always kept secret.

In the end, it is possible to produce excellent beef gut strings as well as tremendous sheep gut strings and vice versa.

Our beef gut strings are produced with an ingenious mixture between modern methods to obtain reproducibility, stability and a rapid production process, and old ones to gain the best sonority and durability.

Whole unsplit lamb gut: only a myth from the past, or are they really different?


whole unsplit gut string

In the production cycle of the XVI, XVII, XVIII and XIX centuries, the animals whose intestines were commonly used in the string-making industry in Rome, Naples, Lyon, Munich, etc. were both goat (expecially in Neaples area) and sheep intestines. The latter category was then subdivided into lamb gut, sheep gut and finally mutton gut.

In the slaughterhouses they used to treat any animal, always for alimentary reasons only; it was then up to the string-maker to select the intestines (coming from different sources and sometimes from very far away) according to their gauges, following the rule, that we have come to know, that the guts of smaller gauge had to be used only for the thinnest strings, and vice versa.

It is particularly interesting the singular situation found in Rome and Naples, where, during Easter time, huge quantities of lambs and young goats were slaughtered, whose intestines were then destined for the production of the Lute chanterelles, which were then sold throughout all Europe.

The common situation that is found in many Italian documents of the XVIII and XIX century is that with three or four whole guts you should get the range of diameters typical of the Violin first string: therefore, the original guts must have been really quite thin.



A Roman document from the mid-17th century (Attanasio Kircher, “Musurgia Unniversalis”, Rome 1650) even reports the interesting information that the first string of a Lute was made using only a single whole lamb gut:

The use of whole guts was therefore the rule in those countries (such as Spain, Portugal and Italy) where there was availability of small animals that allowed the use of three, sometimes four of their coupled and twisted guts, to obtain the range of diameters suitable as the first string of a Violin.

In other countries (France, Austria, Germany, etc.) the situation was quite different: their lambs, either for the breed, the climate or the type of feeding, were larger than those of Italy and Spain, and were never slaughtered at an early age (even for the good quality of the wool) , as opposed to what happened in Italy. Because of the larger intestine section, it was impossible to obtain suitable diameters for the Violin first string: this is the main reason for the huge orders of Lute and Violin first strings addressed to Rome and Naples by the various European nations in the XVII, XVIII and XIX centuries. There are several documents from the XVIII and XIX centuries, especially from France, which analyze well the situation and conclude that, because of their type of sheep, it was impossible to imitate the quality of the Neapolitan first strings.

This type of problem gave origin to the ingenious solution of splitting the intestine lengthwise and halfway in order to obtain thinner strips so as to circumvent the obstacle, a technique that is still used today by virtually all string makers, whether they deal with beef's casings or sheep's casings.

From the documents that were found, it would seem that this technique was introduced in Germany only in the late XVIII century (the German inventor won a prize from the local municipality), while its use was actually known as early as the second half of the XVI century, at least: in the statutes of the string makers of Rome in 1587, 1591, 1642 and 1678 it was in fact forbidden to make strings from intestines 'split in the middle', under penalty of heavy fines or even whip and jail and the  espulsion from the roman stringmaker’s corporation:



In the statutes of Lisbon string makers of the late 17th century it was also stated that a string maker who was discovered mixing whole guts with guts cut into strips would be forced to pay a hefty fine:


It would therefore be a commercial fraud. An Italian document from the middle of 1846 states that the use of strips to make strings instead of using the whole gut, is to be considered a fraud and it also explains how to detect it:



But why in Italy and Portugal were they so strict against those who cut / used the gut in strips? Wasn't it an ingenious system to be able to use even the larger and more available casings?

Until a few months ago, it was commonly believed that a string made from whole gut should have the same acoustic properties as a string made from strips. Our recent rediscovery of the ancient system used in Italy to make whole gut strings has instead shown a completely different reality: strings made of whole unsplit guts have greater acoustic performance, they reach a stable tuning more easily, they are more resistant to traction and also much more stable to climate changes as compared to the same string made out with the same intestine cut in strips.

This series of findings would definitively explain why the strings produced in Italy (and to a lesser extent in Spain) enjoyed the reputation that has always been praised in European documents from the late sixteenth to the first half of the twentieth century and also explains why it was so carefully monitored that there were no fraudulent initiatives by local string makers.


But does whole gut really sound better?


As mentioned earlier, uncut whole gut strings not only have proven acoustically high performance in terms of volume and achievable sound nuances, but also have high tensile strength, fast and stable intonation and resistance to climate changes. If we lived in those past times, we would have certainly done everything to preserve such quality by persecuting any form of fraud.

We asked ourselves what could be the reason for this better sound, stability and mechanical resistance: if we make two identical strings from the same gut (but one of which is obtained from strips) we get very different results.

We have come to the conclusion that the possible 'secret' of this special quality is the result of the natural conformation of the intestine, which presents on the one hand a sort of robust and thin longitudinal 'lace' on which the thin and delicate 'tubing' of the intestine adheres. During the twisting phase, it spreads around the above-mentioned lace which, on the contrary, results in traction at its ends, almost as if to create a hypothetical covered rope whose core is the aforesaid 'lace'.

Here is a video showing this:




What is the FL product?

I installed some new high-quality strings, the nut is perfectly polished and graphite has been correctly applied, but the first string keeps breaking when I get near to the final tuning: why?

“I bought a small harp for medieval repertoire, but unfortunately the strings on the first octave will break right after being installed, even if they are from a well-known famous brand: why does that happen?

Here is the fact: you might have followed the best way to install the strings, and you might have used the best strings on the market, but did you ever look into the Breaking Index (also called FL product) of your instrument?

The FL product
When a gut string is gradually stretched, it will eventually reach a specific frequency at which the string will break abruptly: such frequency is called “Breaking Frequency”.

Counter-intuitively, such frequency will remain the same even with different diameters of the string (the only variation will be in the tension of the string, expressed in Kg). The reason is this: if the diameter is increased of a certain percentage, the tension will also increase of the same percentage (and viceversa).  As a matter of fact, applying Mersenne/Tyler string formula, when changing the diameter and the resulting tension, it will be noticed that the frequency will remain unchanged.

As a consequence, both the following statements start from false premises, and therefore will result not true:

The string snapped: I decided to install a thinner one because it has a lighter tension and therefore it won’t break

The string snapped: I decided to install a thicker one because it is stronger

We have taken several measurements on gut strings of different brands, and the results show that the average frequency value at which a gut string with a length of 1 meter breaks is 260 Hz .

The Breaking Frequency (F) is inversely proportional to the vibrating length (L), so if the length of the string doubles and goes from one meter to two meters, the frequency will be divided in half, and vice-versa. In other words, the product between the two parameters F and L is a constant that, at the unit length of 1 meter, is defined as the Breaking Index, or FL.

When a luthier designs an instrument, he starts, instead, from the frequency of the 1st string: so, dividing the Breaking Index by the frequency in Hertz of the first (and therefore highest pitched) string, we can calculate the vibrating length at which the string will inevitably break.

Let’s make a practical example on a Violin:
The frequency of the first string, the E (considering the baroque pitch of 415 Hz), is 621.7 Hz
Therefore, the vibrating length at which the E string will instantly break is:
260 / 621.7 = 0.418 m = 41.8 cm (Breaking Vibrating Length)

Breaking Vibrating Length and Working Vibrating Length
As we have observed, we can obtain the vibrating length at which the string will instantly break simply dividing the Breaking Index by the frequency of the first string, regardless of the diameter that will be used: these are our Pillars of Hercules.

In order to have a string that does not break, it is therefore necessary to introduce a certain prudential shortening of this limit length, but by how much should we shorten it? If the shortening is excessive, the acoustic performance is compromised: the sound performance of a string, at the same tension and frequency, will be improved if its diameter can be reduced as much as possible by acting on the vibrating length (vibrating string length and diameter are inversely proportional). To find the right answer, let’s take a look at the following graph:



It can be noticed how the string initially stretches a lot (irrecoverable loss of elasticity, also called “false elasticity”) before following the linear stress/strain trend given by the Mersenne/Tyler law.
At some point that linear trend changes ratio, and the line gets steeper. This has only one explanation: the string has lost its ability to stretch; the breaking point is getting nearer, and it’s only 2 or 3 half-tones away.

Speaking of which, Daniello Bartoli wrote in 1692: “a string shall break when it can stretch no more”:



Praetorious (‘Syntagma Musicum’, 1612) provides us with both the length measurement unit and the various tunings of the instruments represented in his tables: after deducing the possible standard pitch, in most cases it was found that the various FL products reached the upper limit of the line (a clear reminder of the common rule of that times to tune the first string to the highest allowed), right before the final steep section; we are therefore at two / three half tones from the theoretical breakage of the first string.

This corresponds to a Working Index of 220-230 Hz·m on plucked instruments (2-3 half-tones less than breaking point); 210-220 Hz·m for bowed instruments (3-4 half-tones less than breaking point), excluding large sized bowed instruments, that work around 190-200 Hz·m (see the several works of Ephraim Segerman in FOMRHI bulletins).



This is also confirmed by our calculations that we have carried out in some historical Lutes and 5 course Guitars kept in museums, provided that the vibrating length has not been altered and that they can be traced back to a sufficiently identifiable standard pitch (see A. J. Hellis:’The History of Musical Pitch’, London 1880, and Bruce Haynes: ‘A History of Performing Pitch: The Story of “A” ‘ 2002).

This is the case of surviving theorboes/ archlutes (for example those of Grail, Buechenberg, Hartz etc ) built in Rome in the 17th century (estimated standard pitch of 390 Hz), renaissance lutes made in Venice in late XVI century- beginning of the 17th century such as for example those of Venere, Sellas, Tieffenbruchker etc  (Venetian standard pitch ‘mezzo punto’: 465-70 Hz), 5 coure guitars made in France in the late 17th/first half of the 18th century -such as the Voboam ones- (standard pitch around 390 Hz), and, finally, the d minor 11,13 course  d minor baroque lutes made in Germany and related Countries in the 18th century (german Kammerton pitch, around 420 Hz), where the calculated Working Index range is 225 -235 Hz·m.


Is there a single Breaking Index, or more than one?

Until today, the average Breaking Index (breacking point) of a gut string has been considered to be 260 Hz·m (statistical average measurement taken by me on several modern gut strings with a diameter of approx. 0.40 mm) while in the 1970-90 it was considered of 240 (Ephraim Segerman concusions).

We have only recently come to understand that it is not possible to consider a single value for all sizes of plucked and bowed instrument: there are at least three Breaking Indexes that should be used (this finally solve the puzle with the calculated Praetorius working index of the instruments of his tables)


Here is the deal: it is commonly thought that gut strings - whether they are thick or thin - are all manufactured following the same chemical procedures, applying the same twisting ratio; using the same type of gut and are finally produced following the same production phases.
Actually, this is not the case: in professional string making technology, at least THREE different types of manufacturing are (or should be) followed, which involve the use of different chemical baths, different twisting ratios, different types of raw gut and, finally, different manufacturing steps.
If we were not proceeding in this way, we could not effectively solve the two main underlying problems of a musical string: the breaking load (breacking point) and the inharmonicity (i.e. the acoustic dampness, which is related to the degree of elasticity of the string, a parameter linked to the twisting level, type of raw material and chemical phases used): these two parameters are in opposition to each other: increasing one will decrease the other (and vice versa).

Therefore, the different string diameters - especially those used as trebles - need their specific technology.
For example, it is not possible to produce a string of a certain thickness with the same technology used for Lute trebles: the obtained string would be extremely rigid and hard, therefore totally aphonic/dull. On the other hand, it is not possible to adopt the technology used for the thickest strings when manufacturing Lute trebles: the trebles would break long before they reach the required note.


The three types of gut strings

(these considerations are related to our own production. We cannot knows which is the situation of other stringmakers)

-The first manufacturing type concerns the super solicited and thinnest strings only – basically Lute and Baroque guitar trebles – where the one and only goal is to reach the maximum tensile strength and the maximum resistance to surface abrasion due to finger's action. The standard adopted Breaking Index of 260 Hz·m refers precisely to this type of strings. No one, here, take care of Inharmonicity

-The second type includes strings that are still considerably under stress, but not at the extreme levels that are typical of Lute/Baroque guitar trebles.
Typical examples of this type are the Violin and Gamba 1st.
Here the goal of the stringmaker is still to look for a high tensile strength, but at the same time beginning to reduce a certain degree of the inharmonicity by modifying the chemical process used.

-The third type is represented by the first strings of bigger stringed instruments such as cello, bassetto, G and D Violone and double bass: with these types of instruments, it is no longer necessary to research for a maximum tensile strength, so the manufacturing techniques aim to reduce the inharmonicity of the string of a good percentage but still not the maximum.

There would actually be a fourth type: the thickest strings that are never used as trebles. In this case, everything is aimed at reducing the inharmonicity as much as possible, taking absolutely no care of the tensile strength.
This is the typical example of the plain gut 3rd string of the cello, the 2nd ,3rd and 4th of the violone in G and D (and sometimes even the 5th and 6th) and the 2nd and 3rd of the double bass - sometimes even its 4th string.

As we have seen, today the commonly adopted value for the Breaking Index of gut is 260 Hz·meter, which in fact represents only of the first type of gut strings: the Lute trebles (in our company this concerns diameters from 0.36 mm up to 0.50 mm).
Always referring to our company, diameters between 0.50 and 0.90/1.00 mm instead are made according to the typical construction criteria of the second type. Experimental data of Breaking Indexes make us converge towards a value of 240 Hz·meter.
The third type is represented in our company by strings of diameters larger than 1.10 mm and up to 2.50 mm. We have not calculated the Breaking Index yet, but by extrapolation we believe that it is further reduced to about 220 Hz·m.

To sum up:
First type of strings (0.36-0.50 mm diameter): Breaking Index equal to 260 Hz·m
Second type of strings (0.50- 1.10 mm diameter): Breaking Index equal to 240 Hz·m
Third type of strings (1.10-1.40 mm diameter approx.): Breaking Index equal to 220 Hz·m


How to put into practice all the above on our instrument?

Simple, by applying the traffic-light rule (this rule is only for plucked instruments; in the case of bowed instrument the orange light turns red, the green light turns orange): green light (little or no breakage risk), yellow light (possible medium risk of breakages, depending on intrinsic quality of the string, environmental conditions such as humidity and temperature, etc), red light (maximum risk, breakage is inevitable).

This is how to proceed: the vibrating length of the instrument, expressed in meters, needs to be multiplied by the frequency of the first string and then:

Lutes, renaissance and baroque guitars (diameters between 0.36 and 0.50 mm)
-if the value is less than or equal to 220: Green light
-if the value is between 220-230 : Yellow light
-if the value exceeds 240 : Red light

Violin, Viola, Gamba family Treble, Tenor and Bass (diameters between 0.50 and 1.0 mm):
-if the value is less than or equal to 200: Green light
-if the value is between 210-220 : Yellow light
-if the value exceeds 220 : Red light


Cello, Violone in D and G, Double Bass (string diameters thicker than 1.10 mm):
-if the value is less than or equal to 190: Green light
-if the value is between 200-210 : Orange light
-if the value exceeds 210 : Red light


Of course, when tuning the same instrument to different standard pitches, all calculations will need to be revised and recalculated.

In our example of the Violin, the vibrating string length that generates the breakage must be reduced by two . three semitones.

The result is as follows: 34.5-33 cms (range of possible vibrating working length at the pitch standard of 415 Hz)


Essential fields of use

Harps in general (also modern harps)

This calculation is particularly useful on harps that, because of their great variety, might not respect this rule: one should mostly concentrate on the first octave, carefully verifying the FL product of either all strings or also in steps. This information should be taken into consideration by luthiers first of all, since they need to plan the harp according to known notes and pitch. Historically speaking, most harps work with the highest octave in conditions of yellow light

Medieval/reinassance instruments

Since no original instruments survived to this day (we make use of iconographic sources only), and the standard pitch of that time is unknown, it’s always worth verifying the FL product before buying any instrument. This information should be taken into consideration by luthiers when they are planning the instrument knowing the note of the first string and the standard pitch to use, as required by the customer.

Newly designed instruments of alleged historical reconstruction

The FL product should be considered in yellow light for Lutes, Baroque Guitars, Reinassance Bass Gambas; it should be considered in green light for bowed instruments, with or without frets (for Violone consider an FL product of 192-200 Hz·m)


Other fundamental applications of the FL product

How can a string maker understand when to change from a gut string to a wound one?

How to understand when a gut string will not have acceptable acoustic performances anymore?

I installed all gut strings on my bass Viola da Gamba, but the 6th string doesn’t perform at all

I’d like to install all gut strings on my Viola: can this be done?

I installed very good pure gut basses on my Lute, but they are too dull: why?


The FL product is the answer. If on the first string the FL product is also called Working Index, on the other strings this index itself can express the Inharmonicity degree of that particular string in the instrument, having the vibrating string length and the frequency.

Generally speaking, the Inharmonicity degree can be considered as an index of acoustical quality; it will be maximum on the first string, and it will gradually decrease on lower strings until the FL product, and consequently the acoustical performance of the strings, will be reduced to a point where human ear will not perceive it as acceptable anymore (it is widely known that strings of growing diameters, placed on the same vibrating length, will become more and more dampened, will be difficult to be brought into vibration, and will give bad acoustic performances).

At that point the only solution is to adopt a different type of string (wound, roped, KF, loaded, etc).

How can one predict when to adopt such different technological solution? Looking at the FL product, of course!


An example for the classical guitar (and all plucked instruments, in general):

The 3rd string – the ‘g’ – of a classical guitar is the last nylon string; its FL product is around 127 Hz·m (using a scale of 0.65 m and a frequency of 196 Hz for the ‘g’ note)

The 4th string – the ‘D’ – is instead a Nylon wound string; its FL product is around 95 Hz·m (on a scale of 0.65 m and a frequency for the ‘D’ of 146.8 Hz)

The principle behind this transition is that a nylon or gut string will not be able to give good acoustical performances when its FL product will be lower than 90-100 Hz·m (on the 5th course of the Lute, the FL product is around 70-80 Hz·m only, but the workaround is using two strings paired in octave).

The 6th course of a Lute will have an FL product of 59-60 Hz·m; the inharmonicity problem is here resolved only using two strings paired in octave (see Virdung 1511) , but this is the lowest limit: under 60 Hz·m the acoustic performance is so poor that even a paired octave will not do, therefore there’s the need to change to a type of strings that will work down to a limit of 39 Hz·m (wound strings, KF, loaded, Gimped, etc).



With the 1st string at 225-235 Hz mt of working Index (that is the best situation for the performance) , the 6th course of a renaissance Lute has an FL product of only 58-60 Hz·m: despite the fact that the inharmonicity problem here is limited by using the paired octaves, this can be considered, generally speaking, the lower acceptable limit for a gut string. In fact, under 58-60 Hz·m, the acoustic performance starts to degrade progressively until it becomes so poor that the paired octaves are no longer enough: it is therefore necessary to switch to a type of strings that will work under 58-60 Hz·m, till the lowest limit of 39 Hz·m, that is the FL product of the 10th/11th course (i.e. wound strings; KF, loaded; Gimped; etc).



On bowed instruments, thanks to the continuous action of the bow on the string, the situation is better: in this case, the transitional FL product can be considered around 90 Hz·m (that is the 4th Bass Gamba and the Violin 3rd). With that being said, it is still possible to have a good performance also when the FL product for the 6th string is of 57-58 Hz.m only, provided that the gut strings of the 5th and especially the 6th strings have a very high elasticity and/or density (roped structure/loaded gut/whole lamb gut).

However, care must be taken so that the FL product should never be under 55-56 Hz.m: under this value, wound strings must be used.

This is the situation that commonly happens with all those instruments whose FL product is less of 200-210 Hz·m.

For example, the 6th D string of a Bass Viol with a scale of 69 cm (at 415 Hz pitch standard) has an FL product of only 48 Hz·m:  if such instrument would have been designed to use only gut strings, using the correct FL product for the 1st string (i.e. 200-210 Hz·m), the FL product of the 6th would raise up to 57-58 Hz·m; as a consequence, the instrument would have a scale of 77 cm, and not only 69 cm.

A pure gut g-string for a Violin at 415 Hz shows an FL product of 61 Hz·m: this means that a pure gut string can be still used, provided that it’s of excellent quality (i.e. very high elasticity). On the other hand, it’s impossible to reach the low c on a Viola da Braccio that has a vibrating length of only 38 cm: its FL product is just 47 Hz·m.

To have a low c in pure gut – of the best quality –, the vibrating length of a Viola should ensure an FL product like the one for the low g of the Violin: 61 Hz·m (in any case, not less of 57-58 cm). Therefore, following the fore mentioned proportions, its vibrating string length should be 47-48 cm (or at least 43 cm as absolute minimum value, that ensures the same FL product of the 6th string on the Gamba family).

Vivi felice




Wound strings for bowed and plucked instruments from the late 17th century to the early 19th century: what do we know?


Nowadays, the first known mention of the appearance of wound strings dates back to 1659 (Samuel Hartlib Papers Project; Ephemerides: “Goretsky hath an invention of lute strings covered with silver wyer, or strings which make a most admirable musick. Mr Boyle. […] String of guts done about with silver wyer makes a very sweet musick, being of Goretskys invention”), followed then by John Playford (“An Introduction to the Skill of Music…”) in 1664. But their further distribution, in the first decades after their appearance, was not at all fast, but non homogeneous and scattered, at ”Leopard spots”.

Italy, a country that has always been renowned for the production of harmonic strings, offers us a document from 1677 where, in an invoice by the luthier Alberto Platner, one can read: due corde di violone, una di argento et un’altra semplice
(“… two violone strings, one in silver and the other one simple…”).

The first iconographic representations of stringed musical instruments using such strings date back to after 1690 (see the pictorial artworks of Anton Gabbiani, Florence, or of the French painter Francois Puget, Paris 1688, and other authors).

According to Rousseau (Traité de la Viole, 1685), it was the violist Sainte Colombe who first introduced them in France around 1675, but the main English treatise for Lute and Bass by Viola dated back to the second half of the 17th century (Thomas Mace: “Musick’s Monument”  London 1676) still does not mention them, but only describes basses in pure gut: the Lyons and the dark red Pistoys.

Claude Perrault (Ceuvres de physique […], Amsterdam 1680 pp. 214-5) has one of his paragraphs titled: “Invention nouvelle pour augmenter le son des cordes” (“New inventions to augment the sound of a string”). This is certainly regarding wound strings.

In James Talbot’s manuscript (1700 circa) the basses of Lutes, Violin and Violin Bass are still the traditional ones, in only gut: that is, the Lyons and the Catlins.

In the first decades of the eighteenth century, wound strings took over almost everywhere compared to the traditional gut only basses, on both plucked and bowed instruments, totally revolutionizing the way of making music up to the present day.

A recently discovered Roman document, dated 1719, not only states in writing for the first time the use of a fourth wound string on the Violin, as an alternative to the usual naked gut, but also states its construction data, in other words the diameter of the core and the wire to be used (see Patrizio Barbieri, 2016: “Musical instruments, gut strings, musicians and Corelli’s Sonatas at the Chinese Imperial Court: The gifts of Clement XI, 1700-1720”).

An important testimony regarding the use of a fourth wound string comes from Count Giordano Riccati (“Delle corde ovvero fibre elastiche… ” 1767) and then, along the course of the 18th century, also from various other Italian, French, Austrian, German and English documents, where the use of wound strings is described also for the following instruments: Viola da braccio, Cello, Double bass, Viola bass and finally Pardessus.

From the middle of the eighteenth century, however, the use of wound strings became a standard everywhere; around 1750-60, the Cello switched to using a wound string also on the third one.




  1. Use of exclusively round wire;
  2. Use of metals such as copper, pure silver, silver-plated copper and brass. There were still no metals such as aluminum, tungsten (or wolfram) or special alloys which began to be used only in the first half of the 20th century.
  3. High-twist natural gut core;
  4. No silk between the core and the covering wire;
  5. Different balance between core and metal winding compared to modern coated ropes (even if made on a gut core).

The strings were made using very simple winding machines:

winding machines


winding machines




The types of wound strings used between the end of the 17th century and the end of the 18th century can be traced back to three varieties:

  • wound strings on a gut core with close metal winding;
  • wound strings on a gut core with open coil winding;
  • wound strings on a gut core with a double metallic close winding.

In the second half of the 18th century, type 1 strings began to be manufactured also on a silk core, but only for plucked instruments (practical tests carried out by us have shown that coated silk strings do not work well under the bow). The strings with close winding on a gut core were those that characterized the entire nineteenth century until the early decades of the twentieth century, when, right after the Great War, those spun in aluminum and/or with partially polished metal wire began to spread.

In the 18th century, type 2 strings were called ‘a demì‘ or more generically ‘demifileè‘ strings by the French.

Their construction characteristic is clearly deducible from their name: their winding had a spacing between the loops equal to the diameter of the wire, or slightly more for plucked instruments (this precious construction indication – the only one of the eighteenth century – comes from Le Coq, Paris 1724, regarding the strings for the five-course Guitar):


For bowed instruments, it is assumed that the metal wire was more spiralized (this way, the horsehair of the bow was not channeled):


This is our translation of what Stradivari wrote: ’Questi sono i campioni delle tre corde grosse; la corda che mostra attraverso le sue spire che l’anima è fatta di budello và ricoperta con una spira molto aperta ad imitazione della pianta Vitalba

(These are the samples of the three large strings; the string that shows through its coils that the core is made of gut should be covered with a very open spiral as an imitation of the Vitalba plant)

the Vitalba plant

An example of the Vitalba plant


The first mention of this type of string, however, dates back to 1712 (Sebastien De Brossard: ‘Fragments d’une méthode de violon’, manuscript), while the last of our knowledge is dated 1782 (Jean-Benjamin De Laborde ‘Essai sur la musique ancienne et moderne’).

The demifilèe strings – always made on a gut core – were used in France sometimes both as the fourth c-string of the seven-stringed viola bass (see the letter of G. B. Forqueray to Prince Friederich Wilhelm of 1768) and as the third of the violin (Brossard 1712 and Laborde 1782):


Five-course Guitars

In addition to the already mentioned Le Coq (1724), we have further documents that confirm the use of wound strings having both gut cores (Corrrette 1761 ca) and silk cores (Don Juan Guerrero: “Methode pour Aprendre a Jouer de la Guitarre”. Paris 1760):

4-course and 6-course Mandolins

Documentation from the 18th century testifies both to the use of demì strings on a gut core and bass strings with close winding on a silk core or even gut (Methods of Fouchetti and Corrette, Paris 1771-72):

Lutes and Gallichons

The first mention of the actual use of wound strings on gut cores dates back to 1715 (Germany); several other French and, above all, German written sources from the 18th century were later discovered, confirming the fact that the 11- and 13-courses lutes used wound on gut cores. Some clues, both in terms of surviving artefacts and iconography, lead us to believe that they were of the demifilè type (we made exhaustive tests using a silk core, but they led to rather disappointing results, both in terms of acoustic quality and mechanical nature).

For example, here are some fragments of bass strings found on a lute by Raphael Mest in Linkoping (Sweden) followed by a German/Austrian iconography presumably from the middle of the 18th century:


On the Gallichon, we found this interesting iconography of German origin dating back to the mid-eighteenth century that, together with general considerations on the construction characteristics of the instrument, strongly suggest the use of close wound basses on a silk core (as already used on the 6-courses Spanish guitar), a hypothesis supported by our practical tests:



Historical documentation and French iconography bear witness to the use of wound basses on silk cores (Baud, 1797-98, Versailles) as well as demifilè, presumably on gut cores:

(Note the strings of the violin behind the harp: 4th wound in silver, and three gut strings)


At the end of the eighteenth century the demì strings went into disuse both because of the disappearance of the specific instruments that used them (viola bass, 5-course guitar, lute, etc.) and because they were replaced, in the plucked instruments, by those of type 1, wound on a silk core, that led to the appearance of the simple 6-string guitar:

Example of wound bass strings on silk cores, for 6-course Spanish guitar, dated back to 1810-12



Contrary to common belief, the demifilèe strings were not strings designed to have a ‘transition’ sound between the upper nude gut strings and the following close wound basses. To achieve this, a normal close wound string with a core-to-metal wire ratio in favour of the core would have been sufficient. The real reason is of a technological nature: research into 18th century wire technology has brought to light the fact that at that time they were not able to make wires so thin as to be able to access the close winding (for example, the thinnest gauge on the Creyseul scale, mid-18th century, concerning the gauge of wire for harpsichord is No. 12, equal to about 0.15 mm). See also on this subject: James Grassineau: “A musical Dictionary” London 1740).

The solution of covering a core by spacing the metal wire brilliantly solved the problem, but introduced a new one linked to the potential difficulties of conducting the bow and to the fragility of the metal winding at the nut.

Type 3 strings:

It is supposed that they were also used during the eighteenth century (G.B. Forqueray in his letter of 1768 explains to Prince Wilhelm that the lower strings of the viola bass should never be made double-covered but with simple winding: this is a clear indication that the double-covered strings were still known/used in those days); this means that, perhaps, they were a strategic solution for those particular bowed instruments characterized by having a very short vibrating length in relation to their tuning.

To cite, for example, the Violoncello/Viola da Spalla but, to be more sure, also the 5th low-B string added to the Double Bass in the late 19th century.


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How to correctly install gut strings in order to avoid breakages and at the same time assuring a fast and stable intonation

At times here in Aquila we are told: “I installed the first string and it broke, so I tried with a second one and it ended up the same way. I have been playing the [violin/viola/cello/gamba] in the last thirty years and I sure know how to install a string…


But being expert musicians and performers is enough to be considered expert installers of gut strings as well?


Critical characteristics of gut strings

As a matter of fact, due to its natural origin, at times a gut string can present a problem: in this case we talk about defective strings.

A string can be called defective when:

  1. it has been excessively polished: at touch and at sight the string may appear good and perfectly smooth, but in fact the external fibers have been excessively damaged, so, little after its installation, the broken fibers will raise from its surface as tiny hairs.
  2. it has very small whitish marks (fat spots) on the inside: such strings tend to break during the initial tuning
  3. it suddenly breaks once installed, far from its constraint points (bridge and nut)

A gut string in itself is very  strong to traction, but it also has some weak points:

  1. the material is not hard, so it suffers from potential sliding or contact points that are even minimally sharp (sharp edges)
  2. it easily absorbs humidity, so in humid environments the string becomes less compact, softer and therefore gets even more delicate on the sliding points
  3. it leads to high friction on contact points, at times it squeezes on the nut and bridge slots, or it may not slide smoothly.

Common solutions, like applying some graphite on the nut grooves, are pretty useless if the slots have not been appropriately created following the criterions suitable for gut strings, like in these examples:

The most important things to be observed, is that the slots are slightly cut and they never have clear bending points, and lastly that the nut is mirror-polished. Only at this point using graphite on the grooves becomes truly effective.

The historical essays, such as Thomas Mace’s Musik’s Monument (London 1676), suggest how the nut of a Lute should be prepared in order to avoid breakages and obtain tuning stability:

Finally, iconographic sources of the XVII century often show a particular nautical knot, called Bowline, that divides in half the traction of the string in two distinct points at the hole on the tailpiece (such use can be limited to the first and highest pitched string)

This is how to tie a Bowline knot:

There are also some other best practices to follow:

  1. tune the string keeping it out of the nut slot and, for bowed instruments, every now and then lifting the string from the bridge: this prevents the sliding on friction points, and assures an even tension on both sides of the constraint points. Put back the string in its slot only once tuned (or very near to its final tuning);
  2. Once in a while, it’s good practice to gently pull the string at half of its length, in order to unload its not recoverable elasticity and at the same time clamping it on its constraint points (this way the string will be almost immediately ready to be played);
  3. Put the string in tension slowly: the material needs time to reach its final state of stretching;
  4. The portion of the string wound on the peg should be as small as possible, making sure that on the first loop the string passes on top of itself, and then closing the spirals without further overlaps: see the indications of Thomas Mace on Musik’s Monument (London 1676).


The following videos summarize all the above mentioned recommendations:

Vivi felice


Mimmo Peruffo

Equal tension/ equal feel: some useful information

Equal tension/ equal feel

In this last decade, the so-called equal tension setting has grown very popular among many players of historical bowed instruments, with the belief that such setting is the exact scientific interpretation of what was being done in the past (and what has been found on some historical documents, especially regarding the Lute): strings must all have the same ‘tactile sensation/equal feel’ of tension.

Physics can prove mathematically that strings that show the same deviation gradient, when an identical weight is applied at the same distance from the bridge, will also have the same tension expressed in Kg (the same deviation gradient produce also an equal feel of tension under the fingers).

What has not been considered, though, is the fact that this mathematical relationship is true only when strings are already in their final state of traction, while it proves to be false if the theorical diameters are calculated using the same value of tension in the Mersenne-Tyler string formula, like most of the equal tension supporters do nowadays.

Huggins, in the late XIX century, was already aware of this difference (just like the count Riccati in 1760).

This is what really happens: when undergoing the same weight, the thinner strings, in percentage, will experience a higher thinning as compared to the thicker ones.

In other words, once they are set into their final state of traction (i.e. intonation), each string will get thinner by a percentage that depends on the twisting ratio and how it was realized (high twist/low twist/roped etc) and expecially its Working Index into the instrument (the FL product).

Such percentage will be maximum for the high-pitched thinner strings (i.e. chantarelles), while it will be gradually lower on the thicker ones .

If the string formula is then applied to the new diameters measured once the strings reach the final tuning (and therefore they are in their final state of traction/tuning), it will be observed that tensions will follow an inverse scalar profile, and also the tactile sensation/feel of tension will necessarily feel reversed as well (minimum on thinner strings, maximum on the thicker ones).

We therefore physically performed all the tests as described by Di Colco, Mozart and Mersenne, contradicting the results that apparently seemed to confirm the “equal tension” hypothesis using the Mersenne/Tyler string formula.

Mersenne itself not only wrote that no player of his time followed his indications, but also introduced a 1/16 corrective coefficient to the string formula, without giving any explanation, and causing some criticism (for example see Daniello Bartoli, 1692).

Attanasio Kircher (“Preludium1”, 1650) provides the number of gut casings needed to make Roman Violon strings:

Est hic Romae Chelys maior, quàm Violone vulgo vocant pentachorda, cuius maior chorda consesta est ex 200 intestinis. Secunda ex 180. Tertia ex 100. Quarta ex 50. Quinta denique ex 30. (19)

These details are very interesting and unique because they define the number of guts to be used to make the strings for this large instrument.

To verify the tension profile from other historical information we know that with three  whole unsplit lamb guts we obtain an average diameter of 0.70 mm (See De Lalande and Count Riccati) . The following is obtained by simple proportion:

1: 2.21 mm (30 guts)

2: 2.85 mm (50 guts)

3: 4.04 mm (100 guts)

4: 5.42 mm (180 guts)

5: 5.71 mm (200 guts)


The Chelys Maior is tuned as follows: E, A, DD, GG, (and lastly FF)

Let’s calculate the tensions considering a ‘Roman’ pitch of 392 Hz and a vibrating length – assumed by us –  of 90 cm. This is the data obtained:

1:  E – 35.50 Kg

2:  A – 26.31 Kg

3:  D – 23.54 Kg

4:  G – 18.88 Kg

5:  F  – 16.64 Kg


The tension profile has a scalar pattern: this is a direct example from the 17th century that demonstrates the scalarity of the tension expressed in Kg. By practical test this tension profile is also very close to an equal feel.

Unfortunately, none of today’s supporters of the equal tension, to the best of our knowledge, has ever done verification tests on what was stated on such documents, therefore trusting blindly what has been written.

As a conclusion, to recreate an “equal feel” setting, the theoretical calculation by the string formula must consider a certain degree of scalar tension.

When calculating our strings, we consider the correct scalar gradient: that’s why we are able to offer “equal feel” settings as they were used in the past, and that’s also the reason why we decided not to prepare “equal tension” settings by the string formula that have no real historical support and create disadvantages to a good musical performances, as Huggings and count Riccati already underlined in the XVIII and late XIX century.

We suggest to inform all customers about this topic, in order to finally clarify this point and avoid the practical difficulties encountered recently when calculating existent string settings.

To know more on this topic:


Vivi felice

Mimmo Peruffo