How can I test if my primary mirror is coated with silver or aluminium? Currently the surface has the appearance of having been sitting under a chalk board collecting dust (this is after cleaning with isopropyl and distilled water).
I found a page on the net describing a technique for rejuvenating silver surfaces using a galvanic cell reaction
(about 1/3 page down on this link but would like to be certain first that my mirror is silver instead of aluminium since there is no indication what the process would do to the latter.