Mirrors tarnish when their reflective backing—typically silver or aluminum—oxidizes through chemical reactions with environmental elements. Traditional silver-backed mirrors are particularly susceptible to degradation when moisture penetrates the protective paint layer and reacts with the silver, creating silver sulfide that appears as dark spots or a cloudy film. This deterioration accelerates in bathrooms due to high humidity and cleaning products containing ammonia or acids that damage the protective backing. Modern aluminum-backed mirrors resist tarnishing better but aren’t immune. To prevent mirror deterioration, use only non-ammonia cleaners, spray cleaners onto cloths rather than directly onto mirrors, ensure proper ventilation in high-humidity areas, and seal mirror edges in bathroom installations to prevent moisture intrusion.
