# Why dishwashers are corrosive to aluminum?

When I put aluminium parts into my dishwasher, they get tainted and they are sometime covered with white dots similar to salt.

I don't think it is aluminium oxide.

What are the chemical reactions that have an effect on aluminium but not other metals?

• I'm not 100% sure, but I think it is just alkalinity. Unlike many other metals, aluminum is amophoteric, so it dissolves in both strong base and in strong acid. Most dishwashing detergents are fairly alkaline, probably at pH 11 or 12 or so. That and the heat may be enough to corrode Al. – Curt F. Jul 18 '15 at 22:43
• Closely related to cooking.stackexchange.com/questions/8375/… – Todd Minehardt Jul 19 '15 at 1:39
• Suggestion: @Curt F, make your comment an answer (as you wrote, sodium carbonate in the detergent, with aluminum, forms sodium aluminate, see en.wikipedia.org/wiki/…) – DrMoishe Pippik Jul 19 '15 at 2:24

• The white stuff is probably ${\rm Al(OH)}_{3}$ (aluminum hydroxide). See here for a general description. – Todd Minehardt Jul 19 '15 at 16:52