Natural Vulcanize at 152°C for 7.5 Minutes For Every Thickness (3.2mm) Castaldo Gold Label Strip Has a high concentration of pure natural gum rubber, which makes it very soft and pliable. The superior quality saves the mold cutter on labour costs when used on difficult molds containing undercuts. Castaldo rubber molds retains its characteristic memory and flexibility long ater other molds have become stiff and crumbly. More beneficial for thicker molds. Castaldo White label Strip Has a high concentration of pure natural gum rubber, which makes it firm but flexible qualities valued by the mold cutter. Thin" molds are made best from white label strip. Castaldo No Shrink Pink Strip Eliminates casting shrinkage without the use of liquid molding compounds. Produces molds of same size as original in less time. The molds made from this are strong, tough and long lasting and can be used by itself or in combination with White or gold label for greatest economy.