Manual mold silicone rubber features description The manual mold design silicon rubber features with the resistance to deformation, good tensile strength as well as low shrinkage, and time of reproduction determined on the basis of customers. To handle this situation depends on different cases. Under the condition of an available vacuum pumping machine, mix the silicon rubber and curing agent evenly and then take it to vacuum chamber to the air. If without a vacuum pumping machine, reduce the amount of the curing agent properly. 25kg/tub.