we recommend use Citric Acid, or Lemon Acid (sold in the supermarket, we use them a lot)!!!
And most importantly, the Lemon Acid is harm free for both us and Environment! Boil the water and put the Lemon Acid in (water:Lemon Acid, 5:1, you can save it for later use). And put the dirty brass in for 1-2 minutes. Clean it with tap water and dry it. Polish it with superfine steel wool, it will shine like gold.
30pcs Antique Brass Tone Base Metal Charms-Bird 13x17mm (13163Y-H-130B)