Stronger together

Christian Bayon reveals the results of several years’ experimentation with improving the stability of a violin’s top and back plates without compromising the sound quality

FIGURE 4b Close-up of the spruce pieces in place on the top plate

Ihave been making violins for 48 years, and was a restorer for 29 of them. I began restoring instruments in 1976 at Etienne Vatelot’s shop in Paris before setting up my own atelier in 1984 in Brittany, and then in Lisbon five years later. During these years I gained some experience in deformations to the violin body. The fall of the Berlin Wall brought a huge wave of migration into Western Europe, with violinists and cellists from Russia, Ukraine, Poland and Romania all bringing their instruments to Lisbon, Oporto, Madeira and the Azores. These instruments were not always in the best condition, and bringing them from climates with very dry relative humidity to a more humid environment had a huge impact on their structure.

All these unfortunate situations for the musicians helped me to understand the stress and deformations of their instruments, mainly regarding the top. I began to explore what it was possible for me to do, as a restorer, at least to prevent the problem from becoming worse.

FIGURE 4a Gluing two spruce struts in the upper bouts improved the stability of the top plate

While working on Cremonese instruments at the Vatelot shop I had already experienced the common problem: that the neck projection tends to drop (figure 1). This is often because the belly can be so thin around the top-block.

THE TECHNIQUE IS NON-INVASIVE, REQUIRES NO REMOVAL OF ORIGINAL WOOD AND – VERY IMPORTANTLY – IS REVERSIBLE

I stopped restoring instruments in 2003, and have only been building new instruments since then. However, many of my customers are permanently on tour, exposing their instruments to significant relative humidity changes, which makes me very concerned about the stability of the neck projection and the string heights. I wanted to ensure that the playability was never affected while touring. For this reason, for the past eight years I have been working on solutions to this problem. I began by experimenting with a new concept for the bass-bar in 2015 (see Trade Secrets, February 2018) and followed it up by trying out different systems of structural reinforcement for the tops and the backs of my instruments.

Some of my innovations have been very successful; others not so much (figure 2). I began by taking inspiration from the leaves of trees, considering how their internal veins are instrumental in keeping the leaf’s shape; its thickness by itself wouldn’t be enough to maintain the structure (figure 3). I also took inspiration from the rigid 3D structures of aeroplanes and boats.

FIGURE 2a An early attempt to increase the strength and stability of a top plate

FIGURE 2b Something similar for the back plate, adding ridges to the C-bout area

Later I tried more simple and direct ways to alleviate the main stress on the violin body, which is the string tension through the neck and top-block. First I glued two sticks of spruce between the top-block and a very strong area: the ‘U’ shape on each of the upper corners (figure 4). These changes improved the stability of my instruments a great deal.

I then started to think about how this technique could be adapted to the repair of old instruments: it is non-invasive, requires no removal of original wood and – very importantly – is reversible. I reasoned that it should be perfect for instruments of the 16th to 18th centuries, and avoid the terrible ‘New York neckset’. This is when you open up the upper part of the top plate (up to the upper corners), pull the neck back to raise the neck projection a few millimetres, and glue the top back again. If the top plate has a little split, you glue the plate at the top of the split – which is not very good for the instrument and makes it harder to open up again. I have seen it done on instruments by Stradivari, Amati and other Cremonese makers. Even more radically, some restorers have fitted some dramatic V-shaped patches near the topand bottom-blocks, killing the sound without any chance of recovery.

FIGURE 3 The internal structure of leaves was an inspiration

Installing these reinforcements would, of course, require the instrument to be opened. However, if a better solution were to be found in the future, it would be very easy to remove the reinforcements without damaging the instrument.

As another possibility, a very efficient method would be to fit a carbon-fibre rod between the top- and bottom-blocks (figure 5). The rod can be installed through the end-button hole, without needing to open the instrument at all. I have experimented with it on old instruments with good results, but I have tried it only once on one of my own violins. Its effect on the sound quality was disastrous. My instrument had plates of normal thickness, and the carbon-fibre tube completely blocked the torsion mode of the body. My theory is that this method will work only if the instrument plates are much thinner – but I haven’t yet dared to build a very thin instrument myself to check the result.