Staining on Brass Finish
Unlacquered Brass finishes are extremely susceptible to "staining" or an undesirable look when they are exposed to moisture. This is due to the lack of lacquer finish to protect it from the moisture. To remove the staining and to delay the natural aging effect, you will need to clean the product with Brasso metal polish.
Furthermore, Unlacquered Brass darkens and develops patina as it ages.