The new F-Red Series for bowed instruments

The F-Red Series are the new synthetic strings for bowed instruments, developed by Aquila Corde Armoniche as a valid alternative to natural gut.

Eco-sustainable, stable in intonation and durable, the new F-Red Series are our answer to the needs of all students and musicians who have to face conditions where the use of gut becomes too demanding, such as

  • high temperature and humidity conditions, typical for example of some sub-tropical countries (e.g. South America and Africa);
  • high cost for the replacement of gut strings that students have to face when approaching the study of ancient music instruments.



  • do not cut the strings because they might get damaged. In case you want to shorten them, first spread some quick glue around the point where you want to cut;
  • once installed, it is important to apply some rosin on the area in contact with the bow before starting to play

How to properly install the F-Red Series synthetic strings

You can pre-order sets and single strings directly from our online shop

Behind the scenes: Mimmo Peruffo and Federico Guglielmo talk about the F-Red Series project


The F-Red Series are new sets and single strings for bowed instruments that have acoustic characteristics well comparable to natural gut.

The F-Red Series are our answer to certain critical situations, such as those found in countries with low economic incomes, high temperatures and humidity, and the absence of local string-makers (i.e. in South America), and where gut strings are available at higher prices as compared to USA or Europe.
Another critical element is represented by students approaching early music, especially youngsters: there’s a good percentage of students dropping out of their studies because of not being able to afford the cost of gut string replacements.
A third critical element is represented by particularly extreme climatic conditions in terms of temperature and/or humidity to which professionals and orchestral formations are sometimes exposed: in these conditions, gut strings would hardly stand up to the situation, so the occasional use of these new synthetic strings (perhaps limited only to the higher string) would allow to manage in the best possible way both intonation problems and potential breakages.

There are three interesting features: the first is their cost, which is lower than gut strings.
A second feature is the tuning speed and stability: while a gut string requires continuous tuning adjustments, once a F-Red Series string has been installed, it requires just a pull with the hands, for the sole purpose of tightening the knot at the tailpiece, and then it will remain perfectly tuned and stable. The stability to climate change is incredible: it is possible to quickly switch from winter to summer temperatures and there is virtually no shift in pitch.
Other interesting factors are the tensile strength and durability. A violin first string lasts  between four and six months, on average, while a bass gamba first string can even last for more than a year.

We decided to use this color to clearly distinguish them from gut strings and thus avoid ambiguities.

Just one: keep them raised from the bridge groove during the intonation phase, and put them back into the groove when the final tuning is almost reached. This avoids potential risks of breaking the surface of the string (not all bridges are well polished). This should also be done at the nut. More generally, this is the method we suggest when installing all gut strings (learn more by reading our blog article: How to correctly install gut strings in order to avoid breakages and at the same time assuring a fast and stable intonation

Producing all diameters, as we do with gut strings, poses several difficulties that we want to avoid. We have therefore decided to align ourselves with modern criteria, where sets are only offered with one or two degrees of tension (the ones representing more than 95% of requests) together with the single strings of these sets. Therefore, unlike gut strings, a full extended list of diameters will not be available.

We currently offer only the sets listed in the tables published on our website.

At the moment, we are not able to offer customized tunings and gauges, or sets for instruments not listed in our tables.

It is a constant ‘work in progress’, so updates may be available in the future.

The following is the current list of instruments for which F-Red Series are available:

– Violin, Violoncello, Bass Gamba (two degrees of tension)
– Viola, Violon in G, Cello da Spalla, Tenor Gamba, Treble/Soprano Gamba (one single degree of tension)

Yes, we tested the F-Red Series on modern violins and cellos, and the results are very interesting and promising. Of course, wound strings employ round wire, not flat wire, so players need to get used to it. In the next future we’re thinking of studying a special line of bass strings using polished silver wire, however, at the moment, this has not been planned yet.

These strings use for the first time original plant derived plastic materials, recently discovered in Italy and derived from sugar cane. The wound strings use varnished red copper instead of the more common silver-plated copper.
This choice was made in order to guarantee maximum durability, less noise under the fingers of the left hand and to meet the needs of those who have allergies to metals.

The answer is no. The owner of this company was the researcher who, after three decades, was able to reconstruct the entire Italian string-making technology based on unsplit lamb gut: The Italian method of making strings from whole unsplit lamb gut: story of a rediscovery

At the same time, he was able to recover the diameters that were commonly used between the middle of the eighteenth century and approx. 1940, giving a technological identity to the wound strings of past centuries, definitively clarifying the question of the equal feel of a set:
Equal tension/ equal feel: some useful information

The purpose for which the Red Series have been designed is exposed in FAQ 2.

The dark red coloring was specially chosen in order to avoid confusion between gut strings and the new synthetic F-Red Series. In other words, the responsibility for the choice is entirely up to the individual musicians and orchestral ensembles.
It makes no mystery, however, that in this particular field of Early Music you can find both a modern violin that uses only the gut string, and exact copies of seventeenth-century violins mounted entirely in gut. In other words we are facing a great heterogeneity.

The definition of ‘historical’ sound simply does not exist; the sound of gut strings varies greatly, depending on the way they are made, and is also a function of the diameters in use. Historically speaking, we also know that there were considerable differences in the construction of the same musical instrument (the Violin, for example, was built in very different ways, depending on the period and on different regions of Europe), as well as there was a complex variety of standard pitches in use. Finally, there was a considerable variety both in compositional and performing practice, generating continuous ‘querelles’ (for example, the one between Italy and France, but also between England and continental Europe, are well known).

Instead of speaking of a recovery of the typical sound of the past, we must rather consider it an attempt to recover the range of sounds used in the past. To make an analogy, if it’s not possible to define the exact Pantone code of a specific yellow color (i.e. to have a unique idea of sound, valid for all), it is instead absolutely possible to say that the general characteristic sounds of the past were in any case within the ‘yellow-family’ of colors. If it was lemon yellow or ochre yellow, this is a topic where discussion will always be open.

Today’s paradox is that it is much more convincing (or within the ‘yellow range’) a totally modern violin using gut strings made using the historical process (whole lamb’s gut, with the average diameters used in the past), than the sound of an exact copy of a Girolamo Amati Violin mounted however with gut strings made in the modern style (very rigid, very thin and even varnished), strings that wwere absolutely unknown in the past centuries, as well as their potential acoustic performance.

The F-Reds Series strings that we are presenting here, are located exactly inside, and more precisely in the middle of such ‘yellow range’. This can be easily verified by doing blind tests with auditors. Since Music is essentially driven by our acoustic perception, we believe that these strings can be used without problems, provided that they can be easily distinguished from gut strings: this is one of the reasons why they are dark-red colored.
With that being said, the F-Reds Series certainly cannot be defined as ‘historical’ strings: only gut strings can be considered as such, remembering however the great variety of qualities, diameters and types that were in use in past centuries.

Unlike gut strings, the F-Red Series strings are made of composite materials, therefore providing a measurement of the external diameter alone is not very meaningful. That’s why we decided to adopt general codes, and to specify the so-called ‘equivalent gut’ in our tables.

Generally speaking, the diameter of synthetic strings is only slightly larger than their natural gut equivalents. As an example, the first string of the 01FG normal tension violin set has a gut equivalent of 0.64 mm and an outer diameter of approximately 0.67 mm.

Listen to the new F-RED strings!

Federico Guglielmo & L’Arte dell’Arco | Milano Arte Musica


Federico Guglielmo violin
Francesco Galligioni cello
Roberto Loreggian organ, harpsichord