Rattle-can paint foaming

I've been battling a frustrating problem while spraying some small items with rattle-can black. In some areas the paint forms little bubbles, making it impossible to produce a smooth finish.

The parts were primed with lacquer-based red oxide primer and wet sanded. The "boiling" only shows up in small areas. Does anyone know what the problem might be?

I used this same brand of paint on bare sand-blasted metal and the results were satisfactory. I'm wondering if there could be either an incompatibility problem; or, perhaps there's a bit of sanding "dust" that's the problem. (Although, I thought I rinsed off the part and dried it.)

TIA for your help.

Orrin

[Harry]

I have found over the years that mixing laquer based paints and enamel based paints can lead to disaster. One can go over the other, but not under. Don't ask me which way this goes because I can never keep it straight. The safe way is to use the same brand of primer as topcoat.

Lately, I've chosen NOT to use a primer coat. If you get a scratch, the primer shows through loud and clear. Instead of primer, I use the phosphoric acid treatment or if that's not appropriate, I bead blast lightly and spray top coat in several layers. Clean is the word!

Bead blasting works excellently when you want to paint galvanized pipe too.

-- Harry

Harry, in case you haven't heard, bead blasting has been obsoleted by Dry Ice Blasting. Now, if only I can get a second and third mortgage on the hovel, I can afford the machine, and really do some interesting blasting. The best part, no abrasive to clean up afterwards.