Black stains on silver powder coat

[jdm2008]

We have a brightsilver powdercoat that we are using. With this paint, we have been having issues that with even light handlingg(think rubbing your thumb with the same force that will turn on a light switch) it will develop a distinct black stain on the powdercoat that cannot be removed. Dooes anyone know what the issue is?

 

[swall]

I would help to know the type of powder, the pre-treatment and the substrate.

 

[IRstuff]

Is it something other than conventional silver corrosion? An uncorrodable silver coating has been a holy grail of optical manufacturing.

TTFN
faq731-376

 

[Compositepro]

The pigment in almost all "silver" paint is aluminum flake, which will turn black when it corrodes. The resin in the paint should prevent corrosion. Talk to your supplier.