[ the craft of the guitar maker ]By TREVOR SEMPLE
8. The Early YearsTHE problem with any varnish, ancient or modern, is that no one type has all the ideal qualities. A hard varnish gives the best protection for guitars or lutes, because they are handled so often. But, if the varnish is too hard, it may chip away or restrict the sound. Hard varnishes tend to be rather brittle, and they find it hard to adjust to the movements of thin, flexible wood surfaces. This can sometimes be seen as 'crazing' - a pattern of fine cracks all over the varnished surface, not unlike the glaze on some Victorian porcelain.
A softer varnish may give acoustically better results, and be more compatible with the wood underneath, but then it often wears very quickly. Old violins give us the best example. The back of the neck is usually grey and rather grubby, in contrast to the brilliant gloss of the rest of the body. This is not because it was made that way, but because the varnish has been worn away use. This has become so much the accepted appearance that modern makers may use little or no varnish on the back of the neck, even if they make a new instrument. The antique has come to dominate the contemporary, and the faults of the original varnish have become a feature!
Luthiers may be entirely justified in making such a decision if it is done out of respect for the past. However, it is just a small step further down this path to the world of furniture, where such attitudes combined with less honest intentions may lead to some distressing practices. If you were a piece of furniture subjected to such indignities, you would be distressed as well, for this is, of course, the term used to cover various ways of artificially aging 'antiques'. They include the use of a shotgun to imitate woodworm holes, soaking in seawater to cause staining and discolouration, and beating with padded chains to cause surface damage suggesting wear.
In the previous article we saw that from around 1550 it was common for luthiers to use at least two different varnishes. This gives rise to the questions: why use more than one varnish at all, and what exactly were these varnishes ?
It is clear that the choice was for relatively soft varnishes, regardless of the limitations. Then why two types? I suspect that the answer lies in one of two possible areas. The use of colour coating was already common, and the art of using colour is to lay it on in dense, thin coats. On an instrument, you cannot afford dozens of lightly coloured coats, otherwise the sound suffocates under so much lacquer Some varnishes, by the nature of the solvents used, are better than others at dissolving organic dyes.
The other possibility is that luthiers required a very thin varnish for use on soundboards alone. Surviving lutes appear to have something applied to the soundboards, but the coating is very subtle. Makers may have chosen to use a different varnish on the soundboard alone out of concern for the sound of the finished instrument. It also suggests that luthiers may have deliberately made a very thin, penetrating varnish for their own specialist use.
Bearing all this in mind, it seems probable that makers had both oil- and spirit-based varnishes at their disposal. Oil varnish can be made from various oils mixed with turpentine. You can add dozens more ingredients as well if the mood takes you. Oil varnish is rather like modern paint. It is thick like honey, and flows well from a brush. It dries by oxidation to become fairly waterproof, and this process is greatly accelerated by ultra-violet light (present in sunlight). Hence the many tales of makers hanging instruments in windows or in sunlight to dry.
Spirit varnish is so named because the resins are dissolved in some kind of spirit, usually alcohol. These varnishes are typically very thin and watery, hold dense colour and dry very quickly. They are difficult to apply with a brush. There is an almost endless list of possible resins that could be dissolved in alcohol.
This brings us to french polish, or shellac. This is one specific type of spirit varnish, and certainly the best known. It is made by dissolving shellac flakes in alcohol.
The resin comes from the remarkable lac insect. In India and South-East Asia they live in their millions on the branches of certain trees, where the female insects secrete a thick layer of brown sticky gum. It is believed this is part of their survival strategy, offering protection from heat or attack. It is an effective deterrent to other insects, as they themselves would suffocate in their own treacle if it were not for the fact that they have evolved their own unusual method of breathing. For centuries, man has harvested the branches of the trees, and extracted the shellac to make 'lacquer'.
French Polish made its appearance in Europe during the very rapid innovations that began around 1760. Rather surprisingly, it was initially something of a military spin-off. At the time, many European military uniforms were brilliant red in colour. The dye came mainly from an overworked little insect in Mexico, and was called cochineal. As demand soared, the cost became crippling, and in the scheme of things it was better to spend the military budget on nasty destructive things like guns, rather than on elegant trimmings like uniforms. So an alternative was sought. At this point, it was noticed that many Indian fabrics were dyed brilliant red, and the base of the dye was shellac. By 1800, large quantities of this dye were imported into Europe, together with a certain amount of shellac resin. But over the next 80 years the balance was to reverse dramatically as more and more new uses were discovered for the versatile resin, including the manufacture of early gramophone records.
Now luthiers and cabinet-makers had access to enough shellac to make their revolutionary new varnish. It had many fine qualities, and they were impressed. French polish dries quickly, and can give a brilliant shine if desired. It has a wonderfully rich reddish-brown colour. It is fairly waterproof in normal use, though less so than most oil varnishes. It wears better than the violin varnish of Stradivari's time. It does not craze, and usually remains somewhat flexible.
There are many fine qualities here, and this accounts for the continued use of French polish in the 20th century. Its use has declined since about 1930 for two main reasons. First, it is rather slow to apply, and therefore comparatively expensive. The furniture and car industries have put considerable ingenuity into developing finishes that can be applied thick and dry quickly, in an attempt to reduce varnishing time. Secondly, we now make far greater demands on our wooden objects. We have become used to plastic surfaces (especially in kitchens) that can withstand heat, and can be easily kept clean with detergents or bleaches. We now expect the same from wooden objects as well. French polish is totally inadequate in the face of such harsh treatment. Luthiers have to make the difficult decision how far they should be influenced by practices developed largely for other applications by other industries.
Next month we will look at some modern alternatives.
©1990 Trevor Semple
"Classical Guitar Magazine", April 1991