Heat treating steel parts is often specified to change the physical properties of the metal. The extreme heating and subsequent cooling creates a thin layer of scale/discoloration (see part on left of picture) on the surface that needs to be removed. After scale removal (middle part), the part can then be polished back to the original or desired surface finish (part on far right).
This stainless steel, medical part was heat treated to harden the metal. The reddish-brown scale (seen on the left) needed to be removed and the part be polished to meet the final specifications. The part was vibratory tumbled with a general purpose (KM Bond) Ceramic Media to remove the scale/discoloration. The subsequent matte, tumbled finish (middle part) was polished to a smooth, bright finish in a vibe with a polishing (KP Bond) Ceramic Media. Each step was only about 1 hour and an appropriate deburring or polishing compound was used for each step.