Restoration of antique furniture was a large portion of my woodworking business during the mid-1970s and early '80s, and now, as then, shellac has proved almost indispensable for this type of work.
Shellac as a finish on wood dates back to the 1600s, with its famed use as "French polish" beginning during the early 1800s.
Shellac resin actually comes from an insect. Bugs known as "Laccifera Lacca" secrete a resin called "lac" to form a protective coating over the eggs they lay. The Lacca bug is found on certain trees throughout India and Thailand and the amber-colored resin they secrete is scraped off the trees and refined into produce shellac.
Shellac also is sold as a dry product in the form of flakes for use in pharmaceutical and food coatings (because of its organic, non-toxic properties). In fact, it is actually used more often for those purposes than as a finish for wood and is available in a wide variety of colors and properties.
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The solvent for shellac is alcohol. Once the flakes are dissolved, the mixture has a limited shelf life. So, taking this into consideration, I usually purchase shellac as dry flakes and mix up fresh solutions every six months or so. Many of the more common pre-mixed shellac products on the market work fine; just make sure that you check the date on the container and test it on a sample board first to make sure it dries well.
"Lac" in its raw form has a certain amount of naturally occurring wax in it. This wax reduces the finish's resistance to water so I prefer "dewaxed" shellac. Aging also decreases shellac's resistance to water, another good reason to purchase it in dry form and mix up fresh solutions as needed.
"Cut" is a term used to describe the amount in pounds of dry shellac flakes that are dissolved in a single gallon of alcohol.
For example, a 2-pound cut has two pounds of shellac flakes mixed with one gallon of alcohol. You can vary the concentration based upon your needs. If I want to seal a surface with some wash coats, I'll spray a one-pound cut (or a pound of shellac flakes mixed with a gallon of alcohol).
It is a good idea to invest in a scale for accurate measuring.
A 2-pound cut works well for padding or brushing. So when using it that way, you can mix a small quantity (say, 2 ounces of dry shellac flakes dissolved into 8 ounces (1/2 pint) of alcohol).
It will take a day or two for the shellac to dissolve. Once it has dissolved, I pour it through a paint filter into another glass jar, label it and date it. To pad it, I make a cloth bob by cutting an inch and a half square of upholsterer's cotton batting and wrapping it with a piece of fine, lint-free cloth.
I like to prepare the wood surface by scraping and sanding with 320-grit paper. After removing the resulting dust, I'll wet the pad and wipe on multiple thin coats. I like to pad it on in parallel rows, whereas some finishers prefer a circular motion.
