lacquer is a formulation that has an additional catalyst added to it at the factory that makes it harden when it cures. You can smell the difference in-between regular lacquer and a Pre-Cat as the Pre-Cat has a distinctly more acrid smell. That’s the acid additive that when applied reacts with the air and the other solvents in the mix to make a chemical cure as appose to just an air dry cure. The benefit is a tougher and more water resistant finish.