Problems with Super Chrome

[Helf8704]

I have coated 2 valve covers with super chrome powder now and both have had the same problem. They both had a lot of small spots or bumps on certain parts of them, not all over but in some spots.

The first valve cover was blasted, then cleaned, then brake cleaned and then coated. I did not preheat the first valve cover to expel oil in the aluminum. I thought that was the problem.

The second one I did today, preheated it for almost an hour at 500 and it still had the same problem. I was told to heat it to a higher temp than the cure temp, that way anything that would come out at 400 would be gone.

I also have an issue with what looks like small hairs in the super chrome, possibly dust in the air? I also added a lollypop blue candy coat and had a couple areas where it did not flow evenly. Is it possible to scuff the surface and add a second coat to fill in the missed spots? I coated this piece within 5 minutes of the chrome curing. Was that too fast? Should I let it cool to 150?

Any help would be awesome!

Jason

[hvac36]

The bumps or small spots sound like outgassing but at 500 degrees for an hour I do not think so but you never know with a used part.
How I do used covers and it never fails, ( well so far it has not) . After blasting I coat in Aircraft Remover ( I know this is a paint remover ) this helps draw out any more grease and oils in the parts. Rince well with water then place in oven at 450 degrees for about 2 hours. Now depending on metal it may flash rust but no big deal, give a quick trip back thru the blaster then use your air to blow it off. At this point DO NOT TOUCH it with your hands..
Powder as normal.
The hairs you see are dust or lint from a rag you used to wipe the part down with ...
Do not re-apply the blue you will have to start over or you will end up with and un-even coat as you have now..

Jim S...

[jtagger19]

sand the area with a 220 sand paper
if you get pinholes that means out gassing if they just get flush with the surface
that mean dirt before you coat , if this is the case just recoat with chrome
small hairs is lint ,did you wipe the part with a rag or paper ?
what I do to eliminate this lint problem is lightly torch the part with a butane hand torch before coating
as Helf8704 said you can't just do an area, you have to coat the whole part to get an even coat .

as for the time to add the coat
I always coat candies at 120-150
some people do it hot
as I always say "the best way , is the way it works for you"

[mtnbiker]

Just my two cents... I almost always do two coats of candy over a chome powder. First coat always seems to be uneven, or not a 'deep' enough color.

And I always shoot after the part has cooled completely.
No hot or warm shooting for me.

[kchotboat]

Originally Posted by mtnbiker

Just my two cents... I almost always do two coats of candy over a chome powder. First coat always seems to be uneven, or not a 'deep' enough color.

And I always shoot after the part has cooled completely.
No hot or warm shooting for me.

I have found you start to loose the candy affect with two coats of the candy color.

[mtnbiker]

Thats strange... I find the opposite.

[FSTFBDY]

Use Lint free rags from a window/glass shop. Ive never had lint problems since I switched to using these. Also wear some latex gloves. Your process sounds good, Your prebaking,etc..

Prep is the KEY!! double check and when you think its 100% perfect double check one more time to be sure.