THE RUBBER-MAKING PROCESS Natural rubber comes from the tree Hevea brasiliensis as 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 form 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 smoked 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 Fillers- carbon black and finely ground silica used to provide reinforceniert oils, waxes, and fatty acids used to improve processability. Pigments used to add coloring to the rubber. The rubber specified for the MI Abrams tank is called carbon black masterbatch. A rough formula for this synthetic rubber is as follows Natural rubber 57.21 percent Carbon black 31.14 percent Oil: 4.03 percent