Fill your sink midway with warm water. Add a few drops of dish soap. Wash your brass item by submerging it in the soapy water and scrubbing it with a sponge. If you can not submerge the item, submerge a soft cloth in the soapy water, wring it out and use it to wipe down the brass item with soapy water.
Rinse your brass item with a clean wet rag, or under a stream of cold water. Dry it completely with a soft cloth.
Mix 1 tsp. of salt and 1/2 cup vinegar in a small bowl. Add flour slowly until you have made a paste of the three ingredients.
Apply the paste to the old tarnished brass item with a paintbrush, or just use your fingers. Cover the item completely with a coat of the paste.
Allow the paste to sit on the brass item for an hour. Rinse the item clean under cold water, or wipe it clean with a wet rag. Buff the item dry with a clean, soft cloth.