What Happens When....

I also use auto acrylics and laquers over an enamel (Humbrol) grey primer and never have any problems. There is only one rule to remember here....let the enamel cure completely!. I prime all my parts and let them dry for at least a week, and if they still smell like paint i give them a few more days. I find the Humbrol primer is practically bulletproof once cured and i can spray whatever i like over it.

Bri -
I've sprayed automotive type acrylic for years with no problems - even over Tamiya acrylic and enamel primers. Mad, you say? Possibly..........I do this mainly because I make a lot of civilian airliners and cars that all have gloss finishes that I need to polish out - the auto stuff takes canding and polishing very well.
I always allow the primers to dry completely, and I apply several "dust" coats of thinned auto acrylic - if you dust the coats on, the "hot" thinner has a little time to flash off before it hits the surface of the model, preventing the hot paint from attacking the primer.
After several dust coats and adequate drying time (as Quincy says, if you can smell it, it's not dry), a thin wet coat is then applied, allowed to dry, then another wet coat. This usually does the trick.
I've never had a problem with the auto acrylic attacking either the primer coats or the styrene. I guess I've tailored my spraying techniques to avoid the normal damage.

Great. Gotcha. So far, my main base coat has ben dyring for over a week, so I think I'll make it here!

Thanks!

B~

If you let the base coat dry completly, you should have no problems with applying acrylics over enamals or vice versa. If you have any doubt as to if the base coat is dry, sniff it - if it still has a paint odor, then it's not dry yet even though you can handle it.

It will work just fine. I use enamel primer all the time without any problems.

What people are talking about is that some paints are more aggressive than others. The general rule is laquer, then enamel, then acrylic. Laquer is the most "Aggressive" and can dissolve enamel or acrylic. Enamel is less and won't hurt laquer but can dissolve acrylic. Acrylic won't hurt either of them.

A lot of people have told me that they paint enamel over acrylic without any problems, but I haven't tried it myself. Just repeating what I've been told. As Karl said, I think the key is to let everything cure thoroughly.

Uillean, I think as long as you allow the base coat to dry fully, ie 24 - 48 hours then you should be fine.

I've used both types of paint over the other without any problems.

Karl