Aluminium Metal pan colour change
I don't know if this is the right place to post this but I thought it is along the lines of kit chatter.
When playing with afew of my new cook sets today I noticed that the aluminiun pans inner surface changed colour from shiney silver to a dull brown. the area of discolouration matches where the heat of the stove was on the outer surface. when I washed the soot off from using the meths burner the outer surface was shiney but the inner surface stayed the dull brown even after vigorus scrubbing.
I can't say I have ever noticed this before on stainless steel pans.
Forgive me if this is a stupid question but is this normal for aluminium? and Why is it doing it?
Inter arma enim silent leges