Let me educate you all on something that each of you has missed.
I've been painting for over thirty years, and I've been modeling even longer. First of all there's no such thing as "acrylic lacquer". This is a misnomer that was introduced in the early 1950's as Ducco Colours by the DuPont corporation. These were described as "enamel lacquers" which is too a misnomer. Everyone who has worked in the painting industry knows for a fact that you cannot mix true lacquer with either acrylic, or enamel as its' formulation is too hot, and won't bind with other substrates. What *** thought that lacquer is, or ever was acrylic, and decided to name it that wouldn't know lacquer if he was DROWNING IN IT!! Lacquer is made from nitrocellulose - tree gum fiber, and NO ACRYLIC paint on the market has this in it - EVER!!! You can make a high V.O.C. (Volume of Organic Content) version of any paint with a solvent base, but true lacquer EATS other substrates causing a lifting, or wrinkling effect. It also crazes (turns white) with other paint finishes which is why you can't spray it over anything else.
Second: Acrylic and any other paint will turn white which is a condition known as "blushing" that is caused by HUMIDITY, and spraying too close! This will happen with any paint no matter what substrate, or base it's made from. Don't spray in more than 70% humidity otherwise you're asking for trouble. Check your local weather forcast first, or if you have a barometer like I do. You'll want to spray no closer than eight inches from the surface, and no farther than this to ensure a smooth coat. Spray no longer that it takes to count three seconds in one twelve inch pass. If you count longer than three seconds, then you're spraying it too long, and if you count less then you're not spraying it long enough. Just spray with a sweeping motion across in one direction starting off the model (in mid-air) so that the spray doesn't blast the surface all at once causing it too pool, or accumulate too much, and keep spraying until you're past the model so that you get an even surface coverage. I use Krylon FLAT CLEAR COAT, and I have yet to get a bad finish surface from it. Let it dry for at least THREE MINUTES before you spray another coat over the surface allowing it enough time to dry so that it can lay down into crevices.
Third: Practice on scrap plastic yard sale signs until you get the desired result. Remember; the spray buttons on most of these spray cans is not the best design, and it will spray like a fire extinguisher if you're not careful to spray it far enough away that you can have more control. If the paint goes on so thin that you can't see it, then you're spraying too thin! This is simple enough to spray it over regular paint finishes. I cannot vouch for any other types of substrates, or mixing weird concontions together then spraying it over your paint without any consequences. This includes any type of floor wax/polishes, or automotive polishes with silicone oils in them.
~ Cobra Chris