The compounds color tends to set out what it is made to be used on. See the attached page from another website for what each is used for. I tend to use what I can get my hands on locally, but if I have to I will order what I need.
http://www.swmetal.com/cart/search?c...ng%20Compounds
Right now, I do not have any on my stuff on the forum---I have done everything that I could get my hands on under the hood of my truck and when I use aluminum to make brackets, I polish them rather than doing a dull finish. For instance, I make fan support brackets for my radiators out of mill strap aluminum from the local hardware and polish it before installing.