Weird effect on bolts for 40

[joeyg1973]

These are the bolt off the engine side cover and timing cover. I have never seen this before. I clear powder coat all the heads of the external bolts I clean up on this engine and only this engine... never doing this again. Anyway I went and put the stuff in the oven and it came out somewhat bronze which I figured was because I hadn't watched the cheap toaster oven and it shot the temp too high. So I throw then in some acetone for a while and with wire wheel I get off the powder coat.

Now just to make sure that there is nothing on them I stuff them back in the toaster oven at 450 for 20 minutes. And... they come out completely bronze now. It comes right off with some quick wire wheel work but unless I can solve why these things are doing that I can't really powder coat them.

What is going on with this metal?

 

[flow2311]

Could they be stainless steel bolts? I don't know what effect powdercoating would have on stainless but the rainbow effect in the first picture looks like stainless??????

 

[dargreg]

I think they are anodized.

 

[73fj40lc]

Buy stainless and be done with it.

 

[65swb45]

I think they are anodized.

.Yup.

 

[rockcrawler]

A solution of water and hydrochloric acid will remove the cad and zinc. Or you can dip them in white vinegar for a couple of days.

 

[joeyg1973]

I never provided the answer as to what was going on here. The problem with the bolts is that I was using a vinyl PC that cured at about 400 which happens to be about the temp that steel will start to blur at. I wound up getting an acrylic clear from Powder By The Pound that cures at 325 and I don't have these issues anymore.