If the black stains appear to be inside the mirror or coming from the back-- moisture may be the culprit and the mirror may have to be resilvered or replaced.
Those are not stains. They are damage to the silver backing on the mirror. There's nothing that will repair the problem. If the problem is around the edges of the mirror, mask off the rest of the mirror and spray paint with mirror spray paint (or any other color of spray paint you want), making a frame around the mirror . While the mirror spray paint does not give it a perfect mirror finish (think old mirrors), it will hide the damage done to the back. Good luck.
I'm assuming the ”stains” are not on the front of the mirror, but the back? If so it means the mirror playing on the back is deterioratin. Can you remove the mirror from the wall or frame? You can recoat the back with a spray mirror paint.
Every time I clean my mirrors, they end up having tons of streaks and almost look worse than before I started. What could I use to clean them that won't leave streaks...
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http://www.howtocleanstuff.net/how-to-clean-black-spots-on-mirrors/
If the black stains appear to be inside the mirror or coming from the back-- moisture may be the culprit and the mirror may have to be resilvered or replaced.
Those are not stains. They are damage to the silver backing on the mirror. There's nothing that will repair the problem. If the problem is around the edges of the mirror, mask off the rest of the mirror and spray paint with mirror spray paint (or any other color of spray paint you want), making a frame around the mirror . While the mirror spray paint does not give it a perfect mirror finish (think old mirrors), it will hide the damage done to the back. Good luck.
I'm assuming the ”stains” are not on the front of the mirror, but the back? If so it means the mirror playing on the back is deterioratin. Can you remove the mirror from the wall or frame? You can recoat the back with a spray mirror paint.
I hav a mirror that is stained on the bottom corner. My remedy is putting a frame around the mirror to cover it up.