The elusive 'art' of guitar finishing...
(First published in Guitarist magazine, issue #462)
The rack of unpolished guitars hanging up in my workshop this week probably signals something I have been putting off for a long time; it must be time to get the bottles out and start the arduous task of french polishing. I’m a big advocate of this centuries-old method for finishing wood, but the long hours needed to complete the process for just a single guitar mean that I often find myself questioning whether I should go back to the drawing board and reconsider my methods. Simply put, french polishing is the process of rubbing minuscule amounts of finish (in this case shellac) onto the surface of the guitar using little more than a handful of cotton wadding wrapped up in a cloth. Over time, these applications can build up to a stunning mirrored gloss finish. If you haven’t seen and played a professionally french-polished guitar, it’s hard to convey how appealing it is. The appearance is different to a modern sprayed finish, which I put down to the fineness of the finish and the subtle way in which it reflects the light. Very little mass is added to the instrument, in fact just a couple of teaspoons of shellac flakes is enough for one guitar. Unfortunately it takes many hours of repetitive, zen-like application to achieve the desired effect and the learning curve is a steep one.
For this reason you won’t find any of the big names french polishing their instruments, but there are many advantages for the small-shop luthier. In my modest workspace the minimum of necessary equipment makes it easy to get going without the need for compressors, spray booths, cleaning stations and all the rest. What’s more, it is generally agreed that the super-thin finish does favours to the sound of the instrument, the theory being that a thicker finish will inhibit the vibrations of the top, killing overtones and suppressing volume in the process.
Unfortunately shellac is not hard wearing and its resistance to the effects of life on the road is poor, so manufacturers in the early-twentieth century looked to alternatives such as nitrocellulose. ’Nitro’ is an ideal middle ground, providing a thin finish that develops the beautiful checked patination we are all familiar with on our favourite vintage Gibsons and Martins. The downside comes from the fact that nitrocellulose was originally used as a replacement for gunpowder, making it extremely flammable, and more than a little hazardous for the small shop luthier.
Polyurethane and polyester finishes arrived later, popularised by other big companies such as Fender. The ‘poly’ finishes are amongst the most durable. Just take a look at any 1970s solid body electric and you’ll probably find that the last fifty years have done little to tarnish the finish. Developed for use on the factory floor, this kind of finish tends to be outside the scope of anything a small scale independent maker is likely to be capable of pulling off easily, without some fairly serious investment in equipment.
Ultimately, no finishing process I’ve found yet has surpassed the meditative joy of french polishing. As the finish builds, every intricacy in the wood bursts into life. Staring into the wood on this level for extended periods brings you even closer to the instrument, and for the first time I can truly appreciate every twist and turn of the grain, every streak of colour running through the timber. Maybe it’s not time to move away from the trusty shellac just yet.
Tip of the month - looking after your guitar’s finish My favourite substance for cleaning is naphtha, better known to us as cigarette lighter fluid. A few squirts on a piece of folded kitchen towel and a bit of elbow grease is all that’s needed to dislodge the worst grime. Naphtha is quick to evaporate, and doesn’t interfere with any guitar finishes, so you can use it safe in the knowledge no harm will result. For the fingerboard, a lemon oil fretboard conditioner does a fine job, and also keeps the bare wood from drying out.
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