The antique furniture restorer Simon Gilboy traces the origin of French polish to a varnish developed by the Martin brothers in 18th century France. Composed principally of shellac --- a resin secreted by the female Lac beetle --- dissolved in methylated spirit or alcohol, the varnish gives a lustrous sheen to wood. You can restore furniture with old or damaged French polish, provided you exercise care and follow some straightforward steps.
Brush a coat of paint stripper over the surface of the wood, using a paintbrush. Leave the paint stripper overnight if possible to penetrate the polish.
Brush white spirit over the paint stripper to neutralise it. Allow the spirit to dry.
Rub the surface of the wood briskly with increasingly fine grades of sandpaper to remove the layers of existing polish. Continue until you have exposed the bare wood all over the entire surface of the piece of furniture.
Apply a dab of wood-grain filling compound to a soft cotton cloth. Rub the cloth over the wood surface. The compound levels out uneven areas of the wood grain to provide the smoothest possible surface for polishing. Rub over the wood surface briskly with a clean cloth to remove any excess filler.
Fold a walnut-sized piece of gauze around a soft cotton cloth, to make a pear-shaped, absorbent pad called a "fad" by antique restorers.
Dampen the fad with a little liquid shellac. Apply the shellac to the wood surface using the fad. Work in sweeping figure-eight strokes, then follow up with strokes in the direction of the wood grain. Allow the shellac to dry.
Rub over the wood surface with 400-grit sandpaper. Sweep away any dust with a clean cloth.
Fold a fresh fad and dampen it with a little French polish. Press the fad against your palm to spread the polish evenly.
Apply the polish to the wood surface with the fad, again using figure-eight strokes and following up with strokes along the wood grain. This process is known as "skinning-in," "washing-in," or "fadding-in." Press as lightly as possible and keep the fad moving at all times. Let the polish dry for 30 minutes.
Rub over the wood surface with fine-grade sandpaper. Sweep away any dust with a clean cloth and apply another coat of French polish.
Continue adding layers of polish and sanding them away until the wood grain is no longer visible and you are left with a gleaming, glassy surface. You may need to apply as many as 30 coats of polish to achieve the desired result. For the final few coats of polish, add a drop of methylated spirit and a dab of linseed oil to the fad.
Store your polishing fad in a glass jar with an airtight lid to keep it from drying out. If the fad does dry out and harden, throw it away and make a new one. According to French polishing expert Simon Gilboy, it can take more than four weeks for newly applied polish to harden completely. You should be able to see the reflection of your hand in a finished piece of French polishing. Practice your French polishing technique on an offcut of wood before tackling a piece of furniture. French polishing is a craft that takes time and practice to perfect.
Seek advice from professional antique restorers before trying to French polish a valuable piece of furniture, as you may damage it otherwise and destroy its valuable patina.