About Alcohols Used as Solvents in French Polishing

by R.M. Mottola

Originally published in American Lutherie #105, 2011



Most any kind of pure or nearly pure simple alcohol can be used as a solvent for shellac, because shellac will dissolve completely in any of them. But the choice of what kind of alcohol to use gets complicated pretty fast when issues of application, availability, price, and safety are considered. The two most common choices for shellac solvents for use in French polishing are ethanol and denatured alcohol, which is nominally ethanol to which some poisonous substance(s) has been added to make it undrinkable. Both of these are discussed here in terms of all of the qualities listed above.

The research behind this article is one of those good examples of one thing leading to another. We were discussing the general availability of ethanol around the American Lutherie cyber water cooler one day, and this led to the realization that both Contributing Editor Cyndy Burton and I suffered from burning eyes when we have used denatured alcohol. This seemed odd, given the generally accepted belief of what is used to denature alcohol (methanol) and how little of it (5%) we believe there is in the mix. This in turn led to a detailed look at denatured alcohols, in terms of chemistry and safety, and this turned up information which I thought fascinating enough to share.