I'm having some problems with paint adhesion on my core support. I'm painting it with Rustoleum semi-gloss black and in one small area it keeps wanting to blister and crack durring the drying process. No matter how many times I go back and sand or clean with alcohol or prime the area again, it does the same thing. Is there anything else I can try? I've ran out of ideas besides stipping that part down to bare metal and going from there. The alcohol isn't creating a reaction is it?

I had to take mine down to bare metal. I sandblasted it in the areas where the radiator sits and other places you can't see. It turned out good after primering and wetsanding it. I painted with the same paint you are using. Although it has been in the garage for about 5 years or so it has held up great and looks good.

First of all stay away from Rustoleum! I believe it contains fish oil which doesn't mix well with other paints....your primer is probably reacting with it. First, clean your surface with a degreaser like Prepsol or some other paint prep solution. THEN, sand the surface. If you are staying with a rattle can paint, use the same brand primer as well. NOT RUSTOLEUM! Try Krylon..I've had very good luck with that. I've used the satin finish black on all my underhood surfaces as well as front suspension parts with no trouble at all. I hate to tell you this, but if you did use Rustoleum, you will more tahn likely have to strip the paint off and begin again. Save the Rustoleum for outdoor lawn furniture. ;)

I used Rustoleum on a ton of other parts on the car and have had zero problems. I was really happy with its quality and finish so I don't think thats the problem. I'm sure it has to do with some sort of little prep issue. I guess I'll have to take it down to bare metal.

Rustoleum is a good quality enamel and is fine for use under the hood. The semi gloss black is very close in appearance to the original equipment black laquer, and every bit as durable.

It sound like you have a contamination problem maybe oil, wax or silicone. Try using some wax an grease remover instead of the alcohol.

Tom

So this is the latest saga on what it looks like. I think I'm going to go down to bare metal, prime, sand, prime again, then topcoat. Is it ok to lightly sand Rustoleum primer?

http://www.imagestation.com/picture/sraid102/pd74a8e7298daa553e613f3d879d204fa/f9be9809.jpg

Doesn't look like a lifting problem, more like the primer wasn't fully dry before applying topcoat? I'd strip and repaint. My .02 Mike

I brushed Rustoleum on my rad support... no issues at all, nor any brush marks.

Sorry to double post, I took mine to the car wash and pressure washed it with regular car soap before painting... it worked well.

Best Spray Bomb is Dupli-Color Semi gloss Black Engine Paint. Costs a LITTLE bit more , but being engine paint , It lasts a long time . I've used it on brackets , pulleys , etc with great results !!!
( Available at any chain auto parts store )

sand it down smooth and put a sealer coat on it. Dupont makes a great sealer and there are also several one step sealers available. Then top coat with whatever you want. Something under the primer is reacting.