How can I prevent mirror rot?

Since mirror rot is a result of moisture intrusion causing tarnish, it’s important to keep mirrors dry. Always use a vent fan when showering or bathing. It’s better to use a towel to wipe a mirror than a squeegee as squeegeeing can cause puddling along the bottom edge. If a mirror is installed where it meets a countertop, we recommend sealing the bottom edge with silicone. It’s a good idea to reseal it periodically as you would with any bathroom caulking. Never use ammonia. Ammonia or any other caustic cleaner will desilver the mirror and allow moisture to enter. Popular blue glass cleaners contain ammonia. Spraying cleaner directly on to glass will make the problem worse, especially if it drips down and is allowed to pool at the edge. It’s a common house cleaning practice to do this. Make sure anyone who will be cleaning the mirror knows not to use ammonia or allow cleaners to puddle.