Classical guitar french polishing

This publication was written as an informal guide to French polishing. This guide is to be used as an informational supplement only. No liabilities are assumed, expressed or implied for any idea, technique or concepts stated in this publication. All right reserved, copyright 2005

Introduction

I built my first guitar on a shelf in the kitchen of my tiny East Village (New York City)apartment in the early1980s. I managed to complete the instrument with limited space and rudimentary tools, but still needed to apply a finish. At the time I couldn’t afford -- nor had I the room for -- expensive spray equipment or a spray booth. I’d seen deep, mirror-like hand finishes on 17th and 18th century antiques, so I decided to do some research and discovered French polishing. I haveembraced this technique ever since.

French polishing is a technique of applying liquid shellac by hand, using a rubbing pad made from cotton and wool instead of using a brush. This technique appears to have originated in France in the 17th century. When applied correctly it produces one of the finest of wood finishes. A mirror-like gloss practically as high as nitrocellulose lacquer can beachieved with a less plastic look. The depth and rich beauty of a French polished surface is unparalleled.

Books from the 19th and early 20th century on the subject all describe French polishing differently, with differences in materials and techniques. The only thing in common was that shellac was used in all methods, attesting to its strength as a finish. Because of this I’ve tried to keepthis tutorial as uncomplicated and as straightforward as possible. The techniques presented here are ones that I’ve used successfully over the years. Presenting every technique ever recorded would quickly overwhelm the novice. The important thing is to learn the techniques presented as quickly as possible and start French polishing. Once you’ve mastered the procedures I present, feel free toresearch and experiment.

Modern finishes were developed in the late 19th and early 20th centuries, but it wasn’t until the 1940’s, after the War, that many small and large guitar manufacturers embraced mass production techniques to satisfy the re-emerging market and to remain competitive. Because finishing a guitar is extremely time consuming, traditional finishing techniques were completelyabandoned. Also, because a mirror-like finish can be achieved with a thin build up of shellac, and because shellac is a delicate finish as opposed to the hard, catalyzed modern finishes, the acoustic properties of French polished instruments are superior to those of any other finish. For this reason there has always been a market for the higher-priced French polished instruments.
A Frenchpolished finish will retain its beauty for a very long time, darkening gracefully over time, wherease nitrocellulose lacquer will crack and yellow over time. Shellac is naturally elastic, so it moves with the with the wood and resists cracking. If a French-polished finish is damaged, it is the easiest of all finishes to repair. A damaged finish can be repaired by the spiriting off, a process whichwill be described in detail later, or by applying more shellac. Mass-produced finishes are more durable, but very difficult to repair.
One of the many reasons I like using shellac is that it is a natural plastic material (made from the secretion of the Lac insect), which is processed into flakes, and alcohol is the only solvent needed. There’s no need for acetone or other toxic solvents.
Thereare six procedures in the French-polishing system I present:
1. Spit coating (the initial application of shellac used to seal all inlays and coat the instrument)
2. Grain and pore filling (the same as in standard finishing, except using different materials and technique)
3. Session (refers to the hand-rubbing process, as opposed to “coats” with brush application). A session is composed of:...