Yes, you can apply TotalBoat Lust varnish on top of lacquer, as long as the lacquer surface has cured completely. Typically, lacquer will through-cure in 48 to 72 hours, but for best results, we recommend that you allow at least seven days for the lacquer to cure in proper conditions before applying Lust. Prior to applying the varnish, use a gray Scotch-Brite® abrasive pad to scuff the cured lacquer surface lightly, and remove all residue.