Q: What causes the Brass finish to deteriorate?

A: There are many reasons why brass metal finishes deteriorate over a period 
     of time. Reactions to paint products that leach onto the finish from the       
     painting of doors, improper use of solvents that are used to clean door locks, 
     different metals contacting each other on metal doors, air quality  and acid   
     rain, and acid washing of brick and mortar surface by the brick mason.