Shellac is a great tool for finishers and restorers because it has a myriad number of uses for furniture. This short blog will aim to quickly familiarize you with its applications in a professional restoration shop setting. That being said, this is merely an academic summation; I would strongly recommend you go out, buy your own shellac, and practice on some test pieces of 400 sanded grit boards. Experience is the best teacher.
Shellac is an natural resin produced by and arboreal insect called the Lac Bug. Today Lac Bugs are farmed on trees in both India and Indonesia, and their resin is used for: pill coatings in the pharmacology industry, an additive mixed into candy and edible products, and it is refined into dry flakes for wood finishing. In reference to its chemistry, Shellac liquid and shellac flakes are soluble in an alcohol solvent. They are not compatible with water, lacquer thinner, or a direct mixing with oil or organic petroleum solvents.
French Polishing is the art form of applying shellac resin by hand on furniture. It’s heyday was around the 1820’s in Europe, when pieces were being refinished and French polished to bring out the natural figure and chatoyance inherent in wood grain. This method of finishing was popular until the 1940’s, when nitrocellulose lacquer was developed, and became the industry standard for the next half a century. As a finish Shellac is not very durable; its very repairable, quite beautiful, and most importantly it’s chemically stable. When I say chemically stable I mean it can be left alone with very little care for over 100 years.
Should you get the opportunity to visit the Winterthur Furniture Museum in Delaware, I would highly recommend closely inspecting the Americana period pieces. Specifically check out the desks, high boys, and chests of drawers. Not only are the pieces masterfully made, their finishes are quite old and still going strong.