The main complaints about using BIN, the shellac-based primer, to seal knotholes is the shellac smell and the difficulty of cleaning brushes. BIN Advanced primer and sealer uses synthetic rather than natural shellac, for a low odor, and is water-based so cleanup is easier—but that also means it must be applied in temperatures above 50° F. It should retail for 20% less than BIN with shellac. Rust-Oleum, 877.385.8155, rustoleum.com
