Which finish has the shortest shelf life?
Michael Dresdner: Shellac has the shortest shelf life, especially if it is very thin. For example, a four-pound cut shellac mixture may last up to three years. A two-pound cut mixture might last only 6 months. Though there are ways to prolong shelf life that the commercial manufacturers can use, not all do so. Next come precatalyzed lacquer (6 months average), water-based coatings (18 months), lacquers (2 to 3 years) and finally oil-based coatings (3 to 5 years, and sometimes longer.)