How to Get Rid Of Dark Spots On Vintage Mirrors

Four ways to remove dark spots from old mirrors

This trick works really well if you have the kind of spots where the backing has been scraped off and you can see through to the other side of the glass.
To do this, you will need to smooth out small pieces of aluminum foil and tape them with clear tape to the back of the mirror.
The reflective foil is seen from the front and is much less noticeable when you hang it back up again. Since you probably already have tape and aluminum foil on hand, this is an easy solution for a few trouble spots!

This is a similar option to the aluminum foil and essentially does the same thing if you have the clear spot issue.
If you have a bunch of small areas all over your mirror, it’s probably more efficient to spray the whole back so any little spots get covered and you don’t have to foil 20 different areas.

Simply tape off a border or design, use a few coats of spray paint and create a new frame that covers up the spots!
I’ve found that most spray paints will hold up just fine when cleaning the mirror with glass cleaner, but you can always buy a small craft mirror and test out your paint first.

Re-silvering is basically removing the protective silver backing of the mirror and reapplying those layers again on the back of the glass.
It is a more technical process (see a full tutorial here), and I think the larger the mirror, the harder it would be for a first timer.
But, it is an option if your mirror’s black spots are overwhelming and totally beyond any other repair.
Since moisture is what caused the spotty damage in the first place, you’ll want to make to protect your new mirror from further damage by using a layer of protective polyurethane on the back.