Why is this metal turning a gray?

[fosgate99]

I attempted to polish my intercooler. It looked like the same metal that my turbo was made out of so i hit it with the black, brown, and then white. It gets the mirror finish but it's not chrome looking. It looks like i painted it gray. I am lost here. What the deal?

[fosgate99]

no one has any clue?

[mcaswell]

Who's the manufacturer of this part? Would they know what it is made of?

It could be a strange alloy of aluminum.

[fosgate99]

garrett makes it. I thought that it was just aluminum. I guess i will try to call them.

[mcaswell]

It could be Pot Metal (Zinc Die Cast)

Place a drop of battery acid on the part in a hidden area. If it fizzes violently, it's Pot Metal.

[fosgate99]

ok apparently it's 536 aluminum that's painted. I just took some medium grit papaer to it and it worked. Now is there something that i can just brush or pour onto it that will take it off? I can't get into some of the spots with the paper.

[mcaswell]

Any paint removing liquid (paint stripper) should work.

[fosgate99]

got it, thanks caswell!