How to antique brass using vinegar:
Antiquing with vinegar has several advantages. Vinegar is easy to obtain and non-toxic. The patina achieved though is not as deep or dark as obtained with other acid methods or ammonia. But it is an easy method to age brass and achieve a nice patina.
brass to be antiqued
plastic container with tight lid
table salt (optional)
Vinegar can be used by directly brushing it over the entire brass piece or by suspending the brass item in the vinegar vapor. The brass should be prepared by removing any protective lacquer, oil and dirt from the surface. See preparation.
In the direct method, results are quicker and a darker patina appears. In preparation, the brass item can be heated with a hair dryer or in an oven to about 450 degrees F. This is optional but will give better results. Using gloves, carefully cover the entire surface with straight vinegar. Allow the piece to dry and note the color achieved. If you want a darker color, the process may be repeated. Once you are satisfied with the patina, wash the piece with water to remove the vinegar residue, halt the patina process and lock in the color achieved.
Another direct method is to use vinegar soaked saw dust. Mix straight vinegar with saw dust to make a paste and place in an air tight container. Coat your brass piece with this mixture and seal the container. Let it sit for several hours or overnight. Remove from the container and let it air dry. Wash off the saw dust paste throughly once you have achieved the desired color.
To achieve a greener patina, table salt can be added to the vinegar solution. Dissolve as much salt as will go into solution with the vinegar and use this mixture to coat the brass piece. Allow the piece to dry with this mixture and then wash off with water as above. You can also sprinkle grains of salt onto a brass piece that has been coated with vinegar to achieve variations in the patina. Areas that are touched with salt crystals will have a green speckles.
Alternatively the piece can be suspended in vinegar vapor. Vinegar vapor will have a weaker effect than direct contact of the brass with a vinegar solution. Place the wooden blocks on the bottom of the plastic container to create a shelf. Fill the container with vinegar to below the top of the wooden blocks. Place the brass piece on top of the wood, carefully such that it is not in contact with the liquid vinegar. Place an air tight lid on the container and allow the vinegar fumes to oxidize the brass. Monitor the progress and when the desired patina has been achieved, remove the piece from the container. Wash the brass with clean water to remove any vinegar residue and allow the piece to completely dry.
Once you have achieved the color you desire, protect the antique brass patina with a coating of wax or clear lacquer.