TIP: Spraying Lacquer Over a Paint or Finish
There are risks to spraying any type of solvent lacquer over any existing, and older, paint or finish. The problem is the lacquer thinner in the lacquer. A wet application can cause many paints and finishes to wrinkle or blister, even an old coat of lacquer itself.
The two easiest ways to avoid problems are to spray several light (almost dust) coats of lacquer to get a bit of a build before applying wet coats, or to apply a coat of shellac before spraying the lacquer.
Both methods will create a barrier to keep the existing coating from being excessively wetted by the lacquer. But a fully wet coat of lacquer, especially if it has been retarded (lacquer retarder added to slow the drying), can still dissolve through and cause a problem. So observe closely what is happening.
Of course, brushing a brushing lacquer, which, by definition, has been retarded so it dries slowly enough to brush, is very risky and should probably not be tried.