French polishing is a method of hand-finishing wood surfaces with many thin layers of shellac to generate a polished surface with all the look of depth. It is a beautiful surface but less durable as other finishes like varnish. It can easily be damaged by alcohol or water nonetheless, it’s a lot easier to fix than other endings. Covering the last coating of shellac using a thin tough layer of wax can help to shield against water damage. French polishing is used on furniture as well as fine musical instruments.
Shellac is the finish employed in French polishing. It is the resin secreted by the lac beetle, located in Thailand and India. Employees scrape the resin from trees that harbor the beetle. It is then dried and processed into flakes. After shellac is dissolved in alcohol, it’s a shelf life of about 12 weeks. Furniture finishers typically mix their own shellac as required, dissolving shellac flakes in denatured alcohol in a rate of 1 to 2 lbs. Of flakes each gallon of alcohol.
Furniture finishers use shellac, alcohol, oil, pumice and sandpaper or sanding tools to generate French polish. The polish is applied with a mat of cotton cloth wrapped around a wad of gauze, cotton or wool cloth which is saturated in shellac. Additionally they use an eye dropper for using oil to the pad and little squeeze bottles to use shellac and alcohol. Pumice is used to fill the pores of open-pored wood such as oak as well as any imperfections.
For the best results, the surface to be polished needs to be absolutely smooth. French polishers first sand the surface as smooth as possible. They start with medium grit sandpaper or power sanding attachments and operate up to finer and finer grits until the surface is perfectly smooth. Then the surface is removed to remove all traces of dust. While implementing the very first layers of shellac, the finisher will scatter little pinches of pumice, which helps to further smooth the surface and fill in any imperfections. Pumice is translucent, contributing to the appearance of depth in the last finish.
The finisher saturates the wad of gauze, cotton or wool with alcohol and shellac then wraps a bit of cotton cloth around it, squeezing it a bit to draw the alcohol and shellac out to the surface of the pad. Then he puts two or three drops of oil onto the surface of the pad. The very first layers will need to dry very fast, so more alcohol is utilized. As the pad has been rubbed in circles and figure-eights on the timber, it leaves very narrow layers of shellac that dry very fast, so that in one session the finisher can employ many layers of shellac. The finisher needs to have the ability to feel once the pad wants oil to prevent dragging and if to include more shellac or alcohol. It is an art to maintain alternating these components to create the perfect finish.
After enough layers of shellac have been applied and have dried, the surface is lightly rubbed with alcohol to smooth any ridges of shellac without removing the finish. It also eliminates any oil that hasn’t become part of the finish. Finally, a coating of a hard wax like carnauba is applied to safeguard the shellac finish.