Cut a square of galvanized steel approximately the same size as the opening of your jar of turpentine. Fold down the corners of the steel so they form four legs. Insert the table-shaped galvanized steel into the turpentine. The surface of the turpentine should rise above the top of the galvanized steel by at least 1 inch; there should be at least 1 inch of space below the galvanized steel top, where the majority of your oil paint will settle. Some people prefer to use wire mesh instead of galvanized steel.
Insert your paint brush into the turpentine and run it over the galvanized steel in back and forth motions. Do not crush your brush against the steel, but apply some pressure.
Take out the paint brush and dab it onto the rag.
Repeat steps 2 and 3 until the paint brush no longer stains the rag with paint.
Take your paint brushes to the sink. Holding the pumice soap in one hand, press the brush into the surface of the pumice soap with the other hand, running it back and forth forcefully, as you did with the galvanized steel. Do not crush the brush against the soap. Froth the soap and then run the brush under the tap, rinsing off the soap.
Repeat step 5 until the soap froth is no longer stained with the color of paint---and then, do it one or two more times just to be on the safe side.