Carbon black contains more than 99% pure carbon. Other components are oxygen, hydrogen, and nitrogen. It is available in powder or beads (pellet) form. The black particles are 10nm to approximately 100nm in size and fuse into chain-like aggregates, which define the structure of individual Carbon Black grades. Depending on the production process parameters, Carbon Black types differ in particle size, structure, surface chemistry, porosity, and many other characteristics. The properties of most Carbon Black grades are determined by industry-wide standards. The American Society for Testing and Materials (ASTM) is the most widely used, especially for Rubber Carbon Black grades.