I have 4 14" aftermarket aluminum rims that I want to clean up and sell. They have darkened some, not polished, and have crevices between the spokes that I need some way to clean. I have heard of some kind of foam cleaner that is supposed to work good but I don't know the name. I also have a sand blaster that I could use but I am wondering if the silica would ruin the rim finish. Anyone have any ideas on cleaning these up?