Carbon black, also known as acetylene black, channel black, furnace black, lamp black and thermal black, is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Its physical appearance is that of a black, finely divided pellet or powder. Carbon black consists of more than 96 percent of amorphous carbon and of small quantities of oxygen, hydrogen, nitrogen, and sulfur. Most of these elements are concentrated on the surface. Subsequently oxidized carbon black may contain up to 15 percent of oxygen.