1. The four ages of gut strings

Though strings made out of gut had been used for thousands of years (gut strings for ancient Egyptian plucked string instruments have been found dating from the Third Dynasty), (5) over the centuries a series of improvements were introduced in the techniques needed to produce a good string. On the basis of research we may conjecture that developments in gut string manufacturing consisted not so much in a slow and progressive refinement of construction techniques but rather in periods of abrupt change brought about by the discovery of new technologies.

Such innovations spread surprisingly fast and often even had the effect of determining the appearance or disappearance of certain categories of musical instrument. This can be verified if we examine the repercussions of overspun bass strings, consisting of a gut core wrapped with fine metal wire (generally of silver but also of copper or brass). These new strings, a genuinely revolutionary discovery, appeared towards the second half of the seventeenth century, spread rapidly and were directly responsible for the swift abandonment of the awkward bass-violins in use until the end of the seventeenth century (or shortly after) in favour of the emerging violoncello (6).

However, it also seems highly likely that, even during periods of relative technological stagnation, string makers probably endeavoured to produce strings to the best of their ability and as perfectly as possible. The rooted idea that the strings of past centuries were a little "primitive" and a long way off the presumed perfection of modern strings needs to be firmly rejected.

As a rough guide, we can outline four characteristic "eras" in the evolution of string making.

The first era. The first era can be approximately identified as the phase in which certain primary materials, especially gut and silk, were discovered to possess a certain degree of resistance under tension and a capacity to produce sound. Due to its wide availability, gut was the material mainly used in the Western and Mediterranean civilizations. Subsequently, manufacturing techniques were improved and rationalized, a step that is reflected in the numerous "do-it-yourself" treatises of the Middle Ages. Here, for example, is a recipe drawn from the "Secretum philosophorum", a fifteenth-century manuscript:

“Ad faciendum cordas lire! Cum autem volumus facere cordas lire [...] recipe intestina ovium et lava ea munde et pone ea in aqua vel in lexivia per dimidium vel plus usque caro se separet leviter a materia corde que est similis quasi nervo. Post depone carnern de materia cum penna vel cum digito mundo. Post pone materiam in lescivia ford vel rubio vino per 2 dies. Post extrahe et sieca cum panno lineo et iunge 3 vel 4 simul secundum quantitatem quam volueris habere et atturna ea usque sufficiat. Et extende ea super parietem et permitte sicare [...]". (7)

The procedures described are surprisingly similar to those used today but, as string manufacturing was not yet a professional trade, the final product must have been rather variable in quality.

The second era. The second period ranged from the second half of the fifteenth to the first half of the sixteenth century. It probably coincides with the appearance of the professional string maker, who perfected manufacturing techniques and raised the quality of strings to the highest possible levels.

During the sixteenth century the main centres of string making were also important for the dyeing and spinning of silk and cotton: Barcelona, Munich and Brussels in the early-sisteenth century; Florence, Venice, Nuremberg and Lyon later. It is plausible, perhaps, that the string makers learned from the more complex techniques used in the spinning of silk: processes that would have allowed a significant initial reduction of the stiffness of the thicker strings used in the bass register. In fact, we may deduce that bass strings were, probably, even more efficient than before, if instrument makers were able to permit themselves important structural developments: in the case of the lute, a sixth course was added some time towards the end of the fifteenth century, thus extending the instrument's range by as much as a fourth (sometimes a fifth) below the fifth course; the same happened to the bowed viol.

The third era. The next era began in the second half of the sixteenth century with a further leap. In this period a seventh course, generally tuned a fourth (sometimes a fifth) below the sixth course, was added to the lute (other additions were soon to follow), while on bowed instruments, string lengths seem to have been reduced (8).

Recent studies (9) have tended to show that these changes resulted from the application of a revolutionary idea: the increase in the specific weight of the gut in bass strings by means of special treatments involving heavy mineral salts. Amongst other things, this is suggested by the seventeenth-century iconography, which shows bass strings of a dark red, brown or blackish colour very different from the typical yellowish colour of natural gut higher strings: in all likelihood, this was a direct consequence of the loading process. This new technique allowed makers to produce thinner yet more sonorous bass strings.

But the most stringent confirmations come from the bass stringholes diameters in the original bridges of surviving lutes. Those holes are too small for a plain gut string to possess the necessary working tension for the right pitch, unless its weight was appropriately increased. Such trick would have granted the production of much thinner and sonorous bass strings than those previously in use, which would fit in those holes with the right amount of tension.

Against this theory speaks the fact that modern  loaded strings, as produced to date, are not transparent; a quality which is allegedly described in the ancient sources. To this point, however,  it must be pointed out how historic documents (with the only exception, perhaps, of the Mary Burwell lute tutor) refer, in fact, to the lute's upper and mid registers, not to the basses.

This phase, corresponding to the age of Monteverdi and Stradella, marks probably a peak in the complexity of gut string making, establishing a level of quality that was to remain unsurpassed.

The fourth era. The last era - which still continues today - is marked by the advent of overspun bass strings consisting of a gut core (i.e. an ordinary plain gut string) over which is wound a fine metallic wire; the windings can be either close or open.

The oldest extant document attesting this technique dates from 1659: "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” (10). This is closely followed by John Playfbrd's viol treatise of 1664 and other works (11). However, the spread of these more efficient basses was not as rapid as one might imagine: the viol player Sainte-Colombe introduced them to France only around 1675 (12), and in Italy, a country renowned for its string production, the earliest evidence is from the year 1677 (13). The earliest extant iconographic evidence of a violin with a white fourth string (probably over-spun with silver) can be dated to the mid. 1680s (14).

It goes without saying that this discovery probably had a dramatic impact on both music and instrument making; it could even be described as a watershed, dividing before and after. For while treble instruments like the violin had always been eminently manageable, the larger instruments were disproportionately unwieldy if we consider the range that was comfortably reached by the fingers of the left hand. It is easy to understand, therefore, that as soon as efficient bass strings became available, the instrument makers shortened the vibrating lengths of several of the da fondamento instruments so as to make them more manageable. This also meant that the violin could use the fourth string more efficently and therefore more frequently than before.