The tools and materials used in French polishing are few and very simple. As a matter of fact, for an investment of a few dollars you can obtain all that is needed to finish a number of instruments. At the end of this article we will list some merchants where dependable materials may be purchased.
Lac is a natural substance that is secreted by the insect “Coccus lacca” often referred to as the lac beetle. This substance is collected from a variety of trees that play host to the insect. The Lac is taken from the tree branches and bark. The harvested lac is cleaned and processed into a variety of different forms including hand processed (shell lac) which is scraped from heated bags of lac. The bags of harvested lac are heated over an open fire. As the lac melts, the bags of lac are squeezed with a tourniquet producing enough pressure to force the melted lac to the outside surface of the bag. Much of the lac is processed into thin sheets which are crushed into brittle flakes for preservation and storage. Most of the shellac is used for industrial purposes while some of the shellac is processed into ready-to-use finishing material which can be purchased in most paint or hardware stores. A great deal of the shellac flakes are processed and sold to professional finishers who specialize in beautiful hand rubbed finishes. Over a period of years the term "shell lac" has become known as "shellac." For one of the finest articles and complete description on how shellac is harvested and processed, you may want to obtain a copy of "American Lutherie No. 54, summer 1998." The article was written by Cindy Burton, who is one of America’s finest luthiers and French polishers.
The shellac that we will be using is sold in flakes. The flakes are available in at least four types. The type of shellac denotes the color, from light to very dark, usually referred to as "white," "blonde," "orange", and "dark". The shellac flakes are then dissolved in alcohol only as needed. The reason for this is that dissolved shellac has a short "shelf life." When a mixture of shellac and alcohol sets for a long period of time it collects moisture and also will be subject to contamination. It should also be remembered that shellac is a natural organic material and will deteriorate very rapidly. It is desirable to mix only what you plan to use in a short period of time. Never use pre-mixed canned shellac from the store to use for French polishing. Ready-mixed shellac is composed of number of additives designed to extend its short shelf life, increase flow, and retard drying time so that it can be applied using a brush. Even though most canned shellacs are of very high quality, the additives that they contain are not suitable for French polishing. Purchase only high quality shellac flakes from a trusted merchant. We will list names and addresses where shellac flakes can be purchased at the end of this article.
We will be using a lot of alcohol. The alcohol will be used for dissolving shellac flakes, thinning, pore filling and other French polishing procedures. Good quality hardware store alcohol is all that is necessary. Some people, however, are sensitive to the materials that are added to the alcohol in the denaturing process. If you are concerned, you may wish to purchase pure alcohol from the liquor store. Again, we will mix only what is required as we work. An open container of alcohol will draw moisture as it evaporates and break down its purity.
Pumice is used for grain and pore filling and is also used as an abrasive at certain times during French polishing. Pumice is often used as a polishing compound for many other types of finishing and is available in most paint stores. We use FFF grade (F stands for floated) pumice which is very fine. Pore filling and the use of pumice is perhaps the most difficult part of French polishing. Once learned however, the job will be straightforward and almost effortless.
Oil is used as a lubricant as we French polish. The shellac is applied using only the muneca or pad. The muneca must be pressed very firmly against the surface of the wood in order to dispense the shellac. This firm pressure also “amalgamates” each microscopic layer of shellac with the previous layer making it possible to “build” a rich and seemingly deep finish. The judicious use of oil allows one to press hard and firmly against the wood without the muneca sticking or dragging. As the shellac is laid on the surface the oil will tend to permeate through the finish and rise to the top. It is therefore important to use only oil that will not get trapped under the shellac and destroy the finish. It is advisable to use only pure 100% virgin olive oil. Other oils such a walnut oil, baby oils, and most types of mineral oils have additives such as antioxidants and perfumes that will tend to trap the oil into the finish itself. The beginner should use only pure olive oil before he or she experiments with other lubricants.
We will be covering some detailing and preparation of the guitar for French polishing as well as the polishing itself. We will include all grades and type of abrasives needed as follows:
220 grit open-coat dry sandpaper
400 grit open-coat dry sandpaper
400 grit waterproof automotive sandpaper
800 grit waterproof automotive sandpaper
1200 grit waterproof automotive sandpaper
The above abrasives are all that you will need to successfully complete your first French polishing project. There are other abrasive materials available which are initially expensive but work much better than sandpapers and last many times as long. If you are a beginner and plan on only finishing one or two instruments a year, the above list is sufficient. If you plan to use the French polishing method extensively, you may wish to order these special abrasives called “Micro Mesh.” We will list the address and phone number at the end of this article.
We will be constructing a rubbing pad or “muneca”(Spanish for rag doll) using wool for the inner pad and an outer covering of a soft cloth such as t-shirt material. The inner pad of the muneca will be wool. The composition of wool is ideal for retaining the shellac inside the muneca until it is forced out by the pressure of the hand. Be sure that you use only pure wool for the inner pad or the shellac will not dispense properly. A well-worn t-shirt is ideal for the outer covering and a cut up wool sock is suitable for the inner pad. Have plenty of soft wiping clothes ready as well. You may want to purchase about a yard of t-shirt cloth from a local fabric store or, better yet, procure a couple of well worn t-shirts. This should be more than enough for the first project.
As we stated before, no polishing compounds or polish is used in the actual French polishing process as we lay on the shellac. When we are finished however, we will need to clean and polish the instrument to rid it of hand prints and any dull areas caused from handling the instrument. For this we use "Meguiar’s No. 7 Show Car Glaze." If a more aggressive cleaning agent is needed, we will use a very fine rubbing compound such as 3M “Perfect It #2 Rubbing Compound No. 05973."