They carry a gouge, a long, sharp knife with a curved blade, to cut narrow grooves in the bark of the tree. It slants diagonally downward about half way around the trunk. The latex oozes out of the cut and goes through the spout and into the cup. Each tree gives about a teacupful of latex, and a tapper usually gets about 350 trees a day. Latex spoils quickly and easily and must be processed into crude rubber soon after tapping.
Most plantations make crude rubber from latex by coagulation.
Tappers pour the latex into tanks and add an equal amount of water and then strain the thinner latex through sieves to remove dirt and bark. Formic acid is then added to the strained latex to make it form solid particles, which thickens it. The rubber particles rise to the top of the liquid and form a white mass of crude rubber. To process the crude rubber, the tappers roll the crude rubber and form a sheet and then shred it into small pieces, which is called crumb rubber. Sometimes they dry the latex over a fire to form large, black balls called biscuits.