On Dec 9, 1:12 pm, Alexander Miller Alex@. wrote:
I have a large wall mirror in our bathroom, secured with the usual
clips. In places the bottom has desilvering or blackening about 1.5
inches up from the edge.

I intend to cover the edges with wood framing to hide the bad spots,
but it would be good to find a way of "stopping the rot." Does anyone
have experience with a product I can safely use to seal the bad parts
of the silvering before I cover them?

It will not stop unless the bad part is cut off. I would take it to
glass shop have them cut off 2 inches, sand the edge and seal the
entire mirror. Shouldn't charge you too much. Actually if you get
lucky the guy in the shop would do this for a tip, $10 or so. Just
have him come out and take a look at it BEFORE going in the office. He
might just do you a favor instead of making a ticket on it. If you get
it cut don't forget you will have to lower your top clips. (if you
were my neighbor, I would do it for free G)