As per your question Peter.... "How to remove the silver from the back of
a mirror ?".   After using stripper to get the painted finish off use
Muriatic Acid.  ( I belive it's used by swimming pools cleaning companies).
However, it will take the sliver off , the problem is, it is so toxic
you have to wear a respirator and do it in a place with good ventilation.
I suggest to take it to your local Mirror Refinisher and have them do it.
That's what I do.

I'm sure there is some other way less toxic, I just haven't heard of it.
I bet some other MMD person will be able to share there ideas.  I would
like to know myself.

Ricky Diggs
Custom Woodworking
www.myfreeoffice.com/woodworking