French Polishing

French polishing is a method of applying finish to wood by hand with a cotton pad. In the guitar world the term “French polish” is understood to be a shellac spirit varnish that has been applied by the French polishing method. Most of the fine old musical instruments made in Europe were French polished, as are a majority of fine classical guitars being hand made today. It is a most highly-prized and desired finish for both its visual and tone enhancing characteristics. The luster, texture and color of the wood are all noticeably enhanced under an expertly applied French polish finish. The cured shellac film is also very thin and flexible and is believed to produce the clearest and most natural sound from the vibrating wood of the guitar, especially the top plate.

Achieving a professional quality French polish finish is highly dependent on the practiced skill and experience of the finisher. Although the method is very labor intensive and time consuming, most finishers seem to receive enough personal satisfaction from the resulting finish to warrant the effort. The application method is very simple with minimal material and equipment requirements. The only materials required are shellac, alcohol, lubricating oil, fine pumice, and a special polishing pad. This polishing pad is made of a small wad of cotton or wool wrapped tightly inside a linen cloth that is held firmly in the palm of the hand during polishing. This polishing pad, lightly charged with the shellac solution, is wiped (“padded”) in a continuous motion over the wood surface with each pass leaving a very, very thin layer of shellac over the last. Multiple polishing sessions are required over many days or weeks to achieve the best results. The French polishing method will be explained in more detail in a following section.

The recipes for shellac spirit varnish are many, but the most basic formula is shellac (Lac button or flake) dissolved in denatured alcohol solvent. Some other recipes may contain small amounts of common gums or resins intended to improve the resulting film in some slight way, but most finishers use the basic shellac/alcohol solution. The finish dries to the touch almost immediately because of the fast evaporating alcohol solvent but it takes weeks or months for it to fully cure.

The advantages of using French polish as a guitar finish are related to both the finish and the process. The beauty of the wood under this finish is undisputed, and it is generally regarded as the best finish for tone. Even with these accolades for the finish, the actual process, French polishing, has benefits for the maker. It is very “organic”, very personal and tactile. The finisher can watch the surface closely as he works and can minutely adjust material and method as the finish slowly builds and improves through multiple polishing sessions. This direct connection to and control of the results will certainly appeal to many craftsman. There is no equipment required, the materials are few and inexpensive, and the finishing can be done in a very limited space. The vapor and material are not hazardous or toxic, no need for air ventilation or face mask. This finish can easily be repaired or refreshed at any time. Additionally, shellac is used as a sealer or initial wash coat under any finish.

Although this list of advantages seems to make this the overwhelming choice for any instrument or situation, here are some drawbacks to consider. Even though a French polish finish is thin and flexible (good for sound) it is not very protective against even minor physical abuse. It will dent, scratch, or wear away in situations that would not affect the much harder lacquer finishes. This padded shellac finish is protective enough for classical guitars that are usually handled very carefully but not at all suited to instruments that may be handled more casually like electric or steel string guitars. To achieve an acceptable finish by French polishing requires the development of skills that are entirely new and different to most woodworkers. This works against the success of the novice builder when finishing his first instruments. The overall time and intense hand work required for French polishing limits its use in the smaller shops with higher production as well. In both of these cases spraying or brushing of some lacquer product may be more appropriate.