Castaldo®Jewelry Molding Rubber has been the industry standard for more than 40 years and continues

Both compounds are unique in consistently allowing one to cut with the knife, not ahead of it, a small but important detail that allows the mold maker complete control.

of mold rubber when received and rotate your stock as the rubber vulcanizes slightly day by day throughout its expected shelf life and is at itspeak when new.

to be the best jewelry molding rubber available for lost wax jewelry casting.

Castaldo White Label^®, the less expensive and firmer of our two grades, has a high concentration of pure natural gum rubber, which makes it resilient and pliable, qualities that the experienced mold-maker values in his efforts to produce high-quality molds in the shortest reasonable time.

Castaldo Gold Label^® contains even more pure natural gum rubber, making it even softer and more pliable. Experienced mold-makers know that this compound’s superior qualities can save them substantially on labor costs when used for difficult molds containing undercuts, where a stiffer mold would break delicate wax patterns or would make their production impossible altogether.

 
The care and labor invested in a Castaldo rubber mold can last for decades. The mold will retain its characteristic "memory" and flexibility long after other mold rubbers have become crumbly and stiff.
• Uncured mold rubber will retain its propertiesaway for up to one year if stored from direct sunlight at temperatures below 70ºF (21ºC). Longer shelf life may be obtained by refrigeration at no less than 32ºF (0ºC). DO NOT FREEZE! Accidental vulcanization through exposure to heat or by excessive aging will make the rubber useless for mold making.
• AVOID storing unvulcanized mold rubber near heat sources such as radiators, furnaces, in hot attics or in direct sunlight. Date all boxes

• Nonetheless even rubber a year or more old can make satisfactory molds, depending on storage conditions and other factors.
Mold rubber may become stiff and hard for weeks or ever months due to exposure to extreme cold. Allow the rubber to return to room temperature slowly or warm slightly (100ºF/ 38ºC) for 1 hour. No permanent damage will result from exposure to low temperatures.
• Do not clean the rubber with cotton swabs or cotton balls as the fibers may be left embedded in the mold.
• Take care to remove loose threads when pulling off the polished cloth backing supplied with the rubber. They may become embedded in the mold.
• Try not to touch the rubber with bare hands, as even