Natural rubber comes from the tree Heuea brasiliensis a s a liquid consisting of cispolyisoprene and water . The fluid flows from a cut in the tree and is collected in a cup. This is what we refer to as latex . The latex is coagulated (curdled), shaped into sheets, and then dried to from crepe rubber. The rubber also can be dried in the presence of smoke. This process changes the color to a light brown and is then called a smoke sheet. Base polymers, however, are not suited for production into the final product in which they are intended. Their properties have to be refined through compounding. Compounding consists of the following