What + apple cider vinegar = blue?

Question

I sprayed my hair with apple cider vinegar, and some of it got on my shirt. Around every snap is now some kind of light blue stain--so what material in the metal creates blue when combined with apple cider vinegar?

snap--a circular metal fastener--an alternative to a button

Answer 1

Copper, probably. Between your hair, your shirt, a snap (whatever that is), and the metal, I'm not sure exactly what you're talking about, but if you have a metal turning blue after acid treatment it likely contains copper. If it's after vinegar, it'd be copper acetate. If you explain what a snap is or clarify your question I may be able to give you a better answer.