One of the projects I am working on I couldn't find the screws for only to realize I had left them in a container of 100% Simple Green for who knows how long, possible a month or more.
At any rate, don't to that! Appears the anodizing has oxidized (???) and most of my light green screws are now black!

It is definitely the finish as when I tried to take a soft brass wire brush to one the black came off to reveal bare aluminum below. Kinda bummed...

