Shellac has several disadvantages as a wood finish. Hot items will mar it, water spills sometimes leave white blotches and it dissolves readily in alcohol. On the plus side, shellac is nontoxic, has unmatched adhesion and is easily repaired. It is also an excellent sealer. This last quality makes it ideal as a barrier coat beneath other finishes. Only dewaxed shellac should be used for this purpose to ensure proper adhesion of the top coat. You can buy dewaxed shellac, but making and dewaxing your own shellac is the best way to ensure a fresh, high-quality finish.
Use a kitchen scale to measure the shellac flakes according to the pound cut you desire for the finished shellac. Place the shellac flakes in a clean glass container. Add the required amount of alcohol. Put a tight fitting lid on the container and shake well. Shake the container vigorously several times over the next hour.
Place the container in a dark, quiet location and leave it alone for a minimum of 24 hours. Ensure that the shellac separates into a clear shellac top layer with a hazy wax layer on the bottom before proceeding. If the mixture doesn't separate, the flakes may be too old.
Insert a coffee filter into a funnel. Place the funnel in a second clean glass container. Slowly pour the top layer of clear shellac through the filter-lined funnel into the fresh container. Make sure you transfer only the clear portion, leaving the murky wax layer behind.
Place a lid on the container of clear, dewaxed shellac. Shellac is best used fresh, preferably within several months of mixing.
Shellac is mixed in "pound cuts," referring to the amount of shellac flakes in pounds dissolved in one gallon of alcohol. A common cut, for instance, is two pounds. To mix a two-pound cut of a more reasonable amount of shellac, use a quarter pound of flakes to one pint of alcohol.