Though there are chemical brass cleaners on the market, try using some of these natural ingredients to clean brass.
How to Clean Brass Naturally
How to Clean Brass Old-Fashioned Methods - New England
How to Clean Brass and Remove Tacky Tarnish
What is the best way to clean brass that is tarnished? - Quora
All-Natural, 2-Ingredient Brass Cleaner - A Pretty Fix
How to Clean Brass Naturally
How To Clean Brass Door Handles
6 Ways to Clean Brass With Everyday Household Items
How To Gently Clean Vintage Brass - Emily Henderson