Thread: Spray paining - Aluminium - paint 'chippy' and fragile. What have I done wrong?

Sorry about the photos - I can't figure out how to post pictures on this new Forum as yet....

Uh - OK. I worked it out!

If I recall when I stripped down my old outpoard back to the bare alloy, I sanded it, then followed by etch primer, which was a greeny- yellow colour, then a paint primer surfacer , then colour coat the n clear coat. If I remember Etch primer should not be left too long before it is coated . Etch is to give a key to the metal. , the following undercoat is the base for the colour, might never peeled or came loose. Your paint looks like it was still too soft for the thickness you applied to have cured correctly and was still soft when the rivets were tightened up and spread the paint. A proper Automotive paint shop should have the correct stuff to use.
Another thing I have found presol sometimes leaves a film which causes paint problems, I've gone over the area after with Alcohol.

24 hours is probably too long to leave the etch before overcoating UNLESS you scotch brite the surface. I'm no expert but think that is the case I learned when painting a car.

Mk1-Oz: So maybe it is because I did not scotch-brite between the etch and the white paint. The etch primer is not coming off, just the white. I didn't think you needed to do that between primer and the next coat

Roverlord: So if I just wait for another week or so will it cure better, and withstand the rivets being applied?

Not sure that I can face stripping it all back again, and re-doing it (sob)

Originally Posted by spudboy

Roverlord: So if I just wait for another week or so will it cure better, and withstand the rivets being applied?

Not sure that I can face stripping it all back again, and re-doing it (sob)

Best speak to your paint supplier, I'm no expert. I've recnetly been using 2 pac but not on any alloy.
Also when I mentioned I painted an outboard, I bought a etcher from Mercury and then their primer and top coat,. So can't comment on your all in one etch primer.

Just some thoughts from previous problems.
Holes and seams often trap residual oils during final clean down. It might be the area around the holes was not as clean as should be.
When pushing rivets through, heavier paint around and in, the hole (draining as holes do) will "pull " surrounding paint away.
The expanding rivet seems to have exacerbated this too.
But- not really helpful for the way forward.
What I would try.
A capful of clean thinners and stiff, fine, modellers brush.
Apply to the chip area only to soften the paint and "feather" in the chip. Let dry for 5 mins or so.
Then same method with some thinned colour to touch up.
No guarantees, but have had good results in the past.

Have a poke and prod in areas away from the rivits to see if anything is lifting. Then put some reasonably strong sticky tape (eg McGuiver duct tape) onto the paint then pull the tape off reasonably quickly. If the paint comes off too then you have an issue with the primer surface but if it stays on then the issue might be rivet area related as above.

I assume you checked with your paint supplier than the various paints you are using are all compatible? Not all paints can go over other paints...

Be prepared to strip and redo. Strip it using a 3M Strip 'n'' Clean disk - really quick but be carefull of heat build up/panel warpage.