When it comes to household objects, most folks spend time looking for ways to remove the tarnish from tea services, copper pots and lacquer-free household and jewelry items that have oxidized over time. On the other hand, brass collectors often want their collectibles and artifacts to have a vintage look and they're not willing to wait around for the years it takes to allow nature to do its thing. A variety of agents contribute to the tarnishing of brass.
The Science of Brass
It helps to know a little about the metal you're looking to tarnish before you begin. Brass is a combination of two metals – copper and zinc -- melted together to create the alloy known as brass. Brass that's not sealed with a clear coating is at the mercy of oxidation, so the copper and zinc weather and turn color. The result is a weathered, antique finish that's prized by people who want their brass pieces to have the appearance of being vintage objects.
Liver of Sulphur Tarnishes Brass
The name sounds odd, but you'd be hard pressed to find a tarnishing agent as popular as is Liver of Sulphur (known in jewelry circles as LOS). This compound is manufactured by many companies and does an amazing job of adding a dark patina to metals that include copper or silver. It's important to apply LOS to your brass object in a well-ventilated room with gloved hands since this is a chemical. Reconstitute LOS by putting a "pea-sized" ball of the agent into a glass bowl larger than the object you want to tarnish. Fill the bowl with hot water, stirring with a stick until the ball dissolves. Lower your brass into the bath. Allow it to soak until the tarnish reaches to color you desire. Remove the brass, wash and dry it.
Vinegar and Salt Tarnish Brass
Avoid harsh chemicals by using household products to tarnish your brass. Soak your brass in a mix of two cups of vinegar and two tablespoons of salt for half an hour. Alternately, follow the advice of other brass tarnishing experts and make that solution all apple cider vinegar. Dry the brass with a paper towel, place it on a cookie sheet and bake in a 450-degree oven. It should only take a few minutes to turn the brass dark and give it the antique look you seek; keep the oven light on so you can remove your brass once it's sufficiently tarnished.
Ammonia Fuming Tarnishes Brass
If you're willing to try a riskier tarnishing method, consider the ammonia fuming technique. In an empty 1-pound metal can, dissolve two tablespoons of salt into one cup of hot water. Add ½-inch of household ammonia. Don rubber gloves. Dip your jewelry or small brass objects into the bath and then suspend the objects over the ammonia solution with clothespins. Secure the lid. Run a hair dryer over the can for two minutes to "fume" the brass. You can repeat the dip-hang-fume cycle up to six times. Remove the brass, rinse with water and allow items to dry.