6061 vs 7075 aluminum testing?

If you already know that the samples are either/or, use a file, the crispy pieces are 75. If you don't know the alloy, you can only guess that you

*may* have 7075. You could also have another 7000 series alloy, among others. Another way, knowing the either/or, is to put a bit of water between 2 pieces and leave them for a few hours. The 7075 will start turning black.

michael

Call your local scrap yard---They test the swarf to be sure there is no 7075 mixed in with 6061.......Zinc is intentionally alloyed into 7075 but is a contaminate in 6061.

I think they use sulphuric acid, put a sample in a clear bottle and shake........ then they hold it up to the light and look at it---I dont know what it is they are looking for though