Polishing various types of metals can often be a challenging process using just mass finishing. This difficulty is often compounded with softer metals such as copper, aluminum and brass. The picture above shows the before and after of a brass plate. The plate on the left shows heavy oxidation and light scratches. After just 4 hours in a barrel tumbler with a Stainless Steel Round Ball and a neutral pH compound, the part was cleaned and polished to a near-mirror finish. This part is now ready to be hand polished to a mirror finish, if necessary.