painting Williams F-3 truck side frames

That looks LikE fish eye to me, meaning the trucks were coated with some kind of grease or oil. Try cleaning them wish dish soap first and dry thoroughly, then repaint. If it happens again after you do that with factory paint it likely is an attack of laquer based paint over enamel.You will have to strip the ones you painted, then repaint.

Rob

I'd clean them with a good solvent, air dry and shoot with Dupli-color gray sealer #1699 and then try your color once dry. 

The sealer prevents any reactions. 

Agreed the black encountered something....but can't tell from pics. 

I don't think the paint was the problem. I think there was either oil, grease, or mold-release on the trucks. I recently painted a set of blue Williams trucks Krylon black, and had no problems. I de-greased them using automotive degreaser, scotch-brited them as well as I could, blew them off, and they came out fine.

I'd get a small can of brake fluid (my favorite for metal and plastic is Castrol GTLMA), soak them in it for a day or so, periodically scrubbing as much old paint off as possible with an old toothbrush. Then i'd give them a good washing and toothbrush scrubbing in mineral spirits, paint thinner, or automotive prep-sol (whatever i had on hand). Finally a washing in warm water and dish detergent followed by a rinse and dry.

Inasmuch as i usually prime everything before painting, i'd prime and then paint. However, my guess is that after following all the steps outlined above priming wouldn't be necessary, but after all that work i'd prime them to be certain to avoid the same problem again.

jackson

hello guys and gals...............

Is it possible to just remove both paint with a can of paint remover and to start over with a clean unpainted metal castings ?

Tiffany

Yes.....solvent as I suggested earlier......

Or a gel paint stripper.

Just be careful and wash parts after strip before paint. 

Yes, as i suggested in my earlier post. I've always used brake fluid as that's what i've had on hand. Paint stripper will work as well. Also, i've been told but haven't tried it, EasyOff oven cleaner works well as a paint remover.

Whatever you use be sure to clean, and clean well all the stripped parts before painting.

jackson