“French Polish” is the finish most often found on hand-built classical guitars. French polish is a process, a combination of shellac and how it is applied to the guitar. It is not a product that you can buy at a hardware store. My purpose here is not to go into depth about the process, but to explain a few properties of this type of finish to those not familiar with it.
First, briefly consider other finishes. A lot of “factory guitars” are finished with Nitrocellulose lacquer or Polyurethane that are sprayed onto guitars. Those finishes can be pretty thick and tough and look glassy and glossy. These finishes look good when new and are resistant alcohol, but they are not the best for sound (or in this beholder’s eye, beauty). While anything is possible, these finishes are not easy to repair.
My guitars are French polished. They sound better that way. Also, I don’t have to have expensive specialize equipment to spray and to protect me from lacquer or poly, although I have brushed on lacquer once (enough). I find lacquer very unpleasant to apply and during the drying/curing period!
French polish is a “Spirit Varnish”. The ingredients are shellac, alcohol, and some oil. Non-toxic and even edible ingredients!
A carefully applied French polish finish is attractive, transparent, thin, and light. Because of these attributes, French polish finish is much easier to scratch or dent. Expect some dings and scratches. You can minimize those by learning to handle guitars carefully and with respect. If you touch the top with your nails, you can expect some scratches and dings. We all do it, but we can learn to do it less often! Some great players have guitars that look like they have been played hard, and others look immaculate after years of playing. The first mark can be upsetting, (nobody knows this better than the luthier that applied the finish) but usually no real harm is done.
Sometimes people’s sweat, skin oils, and body heat (!) can mar the finish. This is dependent upon individual’s body chemistry and habits. The finish sometimes dissolves where the guitar touches the player’s chest or right arm. This only happens to certain people who practice for hours on end. Sometimes you might see players put a cloth between the guitar and their body, or wear a sleeve on their right arm to protect the finish where the guitar touches their body.
Heat is another enemy of French polished shellac. Don’t leave your guitar in the sun, or in your car’s trunk on a hot day! Don’t leave it right next to a heater! The reasons go beyond damage to shellac. I think I should make a post about threats to guitars in the near future…