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 French Polishing
French Polishing is the name given to the process of coating wood with a solution of shellac dissolved in alcohol, using a "rubber" made of rag and cotton wool instead of with a brush. The alcohol evaporates, leaving the shellac deposited upon the wood. French polishing is the only finish we work with and when applied correctly it produces what is possibly the finest looking finish for furniture.
Shellac was first introduced into Europe about the 16th Century, but the term FRENCH POLISH was not used until about 1820, when the process was developed by a French cabinet maker.
Basic raw material of French Polish
Shellac is an encrustation surrounding an insect known as Laciffer Lacca, which is a parasite living on certain trees in India and other Eastern countries. The insect is about a 50th of an inch long and has a life cycle of about six months. The shellac is gathered by cutting the infected twigs from the trees. In this form it is known as Stick Lac. The shellac is scraped off the twigs and washed with water to remove the particles of twigs and other impurities and when dry, is known as Seed Lac. This is put into canvas tubes and heated over a fire. One end of the tube is fixed and the other is rotated to squeeze the molten shellac through the Hessian as it melts. The initial shellac that comes through is clean and small amounts are dropped on to a cold stone, where it sets in the form of a thin disc up to about 3" in diameter. This is known as Button Lac from which Button Polish is made. The next amount of shellac that oozes through may contain impurities which would easily be detected visually if the shellac was in the form of a button and it is, therefore, stretched into a thin sheet and crushed, when cold, into flakes, from which French Polish is made. Modern processing plants now exist for producing machine made shellacs, similar to the hand made varieties. White and Transparent Shellac is made by dissolving the Seed Lac in a hot caustic solution of water and then bleaching the solution with chlorine. After bleaching the caustic is neutralized with an acid, which causes the shellac to precipitate out of solution. In this form it is known as Bleached Shellac. Bleaching shellac alters its chemical properties, so that unless it is dissolved in alcohol within 3-4 days after bleaching, it will become insoluble. Shellac contains a very small amount of wax from the insect. The wax is insoluble in alcohol and causes the cloudiness which can often be seen settling towards the bottom of the container. Transparent Shellac is made by removing the wax from the bleached shellac by washing it with a petroleum solvent, which dissolves the wax but not the shellac.
French Polish
French Polish is both a proper and collective noun. As a collective noun it covers all polishes made with shellac and alcohol. As a proper noun it refers to one specific type of material made from flake shellac dissolved in industrial alcohol. It consists of approximately 250 - 300 grams of shellac per liter. The type of shellac used can vary considerably in quality and colour, from pale orange to dark brown. French Polish is suitable for use on all dark woods and light woods, when a light to medium brown tone is required. Button Polish is used to obtain a more orange or golden tone. On light coloured or bleached woods, where it is wished to retain the natural colour, White French Polish, which has a milky appearance, or Transparent Polish, which is almost clear, should be used.
Preperation of the surface for French Polishing
Preparation of the surface for French polishing is extremely important. Any slight imperfections which might not be noticeable under varnish or oil finishes would be apparent under French Polish. It is essential, therefore, that the surface is clean and fine sanded. Furniture that is being renovated should be cleaned to make sure that it is free from wax and grease. This can be done with white spirit and fine steel wool. If the finish on the furniture is in a very bad condition, and is scratched or stained, it would be best to remove it completely with Paint & Varnish Stripper.
If, after stripping, the wood is still stained, it may be bleached with Wood Bleach. If the wood is open grained and a smooth mirror-like surface is required, the grain should be filled, before French polishing, with Grain filler, or extra coats of French Polish must be applied which are then cut back with fine glass or garnet paper until the grain has been filled with the polish. If the wood is to be changed in colour, it may be stained before french polishing, with Wood Dye. This is supplied in 10 wood shades which may be inter-mixed to make a wide range of other shades. If the grain of the wood is to be filled with Grain filler and the colour changed, then the filler can be mixed with the Wood Dye, so that staining and filling can be carried out in one operation.
It should be noted that wood can only be stained to a darker shade than its existing colour. If the wood is required a lighter shade, then it must be bleached first with Super Wood Bleach and then stained to the required colour. Holes and cracks should be filled with Wood stopping before polishing, but it should be noted that where Wood stopping has been used, it will always be noticed, as the pattern of the grain has been broken. The area filled with Wood stopping can be made less noticeable by painting a grained effect over the Stopping with artists colours and a fine artists brush.
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