New brass is a very shiny metal that may or may not fit in with the decor of a home. However, you can change the colour of brass by ageing it. There are several different methods for ageing brass that can help you achieve the desired look and colour, depending on your creative preference.
Remove any varnish. Varnish can be flammable and it's reactive as well, which could ruin the look of your brass altogether. Wipe the item down with acetone before doing anything else. Depending on the desired effect, choose one of the following steps to complete the project.
Paint vinegar onto the brass with a paintbrush and allow it to sit for 10 minutes before washing it off. Vinegar will cause oxidation which would have happened naturally over time anyway. Rinse the vinegar off and repeat if necessary for a tarnished gold look.
Apply 2 tsp salt to a quart of warm water and mix well. Paint the water onto the item and let it air dry. Repeat the process until the desired look is achieved. Salt water takes longer than vinegar, but will give it a mottled aged look, almost like tarnished gold.
Scrub the brass with a soft bristled brush under warm water using a few drops of dish soap. Rinse well. Place the piece in a bowl with 1 tsp salt and 1 cup vinegar for one hour before rinsing well with warm water and drying completely. The salt and vinegar amounts can be increased in those increments for larger pieces of brass. This will give the brass a warm, honey colour.
Hold the brass item by tongs over an open flame for several seconds and immediately immerse the brass in cold water. The burner of a gas stove works well for this. The brass changes to a gingerbread colour.
Place the brass item in an airtight plastic bag with an old cloth soaked in ammonia. Leave this until the desired colour is reached and take it out and rinse it well with warm water. Ammonia fumes will give brass a greenish-brown colour, but don't let ammonia touch the brass as this will cause spotting.
Ventilate well when dealing with chemicals such as ammonia and wear gloves and safety glasses.