Instructions for CASTALDO® SILICONE

The CASTALDO® family of silicone Jewelry molding rubbers are synthetic rubber compounds especially designed for use in the lost wax casting of jewelry.

MOLD PACKING: Place one or more layers of rubber at the bottom of the mold frame. Place the model in position and then pack more rubber around the model with your fingers until the frame is full, taking care to fill any cavities in the model or voids. DO NOT attempt to save a small amount of rubber by using a straight edge to level off the rubber with the mold frame. A little bit of extra rubber will assure that the mold will fill properly and that the rubber will flow into all model cavities.

The cure system used with CASTALDO® silicone jewelry molding rubbers is NOT compatible with those used with natural rubber compounds. Mold frames, mold plates, models, sprue formers, etc. used with one type of rubber compound should be cleaned thoroughly with solvents before being used with the other type.

CASTALDO® silicone jewelry molding rubbers CANNOT be mixed in the same mold with CASTALDO® White Label®, Gold Label® or No Shrink Pink® rubbers.

MOLD MAKING: CASTALDO® silicone jewelry molding rubber compounds are compatible with all mold making techniques including mold cutting and powder and cream separation.

They are particularly adaptable to the powder and cream separation processes since the parting line is so easily controlled. Merely push the model into rubber to the desired point. If not satisfied with the results, remove the model, smooth the rubber over with your finger or tool and re-insert the model. Dust the rubber and model with powder or coat them with mold cream before finishing mold packing.

VULCANIZATION: Vulcanize most CASTALDO® silicone jewelry molding rubbers at 330°- 350° F (165° -175° C) for 15 minutes per layer. Special compounds may require different temperatures. Please consult the instructions for those compounds.

MOLD CUTTING: CASTALDO® silicone jewelry molding rubbers are strong, but not as strong as natural rubber compounds such as White Label®, Gold Label® and No Shrink Pink®. Remember to pull GENTLY while cutting the mold because of this difference. Molds cut like butter - first time users should go easy and be extra careful.

BURNING IN SPRUES: CASTALDO® silicone jewelry molding rubbers can be burned in the usual manner to add sprues or correct details but higher temperatures are needed. Use adequate ventilation!

CAUTION: Vapors given off during vulcanization may produce temporary eye, nose and throat irritation among certain susceptible individuals. Use with adequate ventilation.

STORAGE: As with any unvulcanized rubber compound, store away from any source of heat and light. Unvulcanized shelf life is at least one year if properly stored except for low-temperature cure compounds. The storagelife of those compounds can be severely shortened by unintentional exposure to heat in shippingand storage.


The information contained herein is believed to be accurate and reliable; however, it is the user's responsibility to determine suitability of use.

Goodwin Refractory Services Ltd warrants only that its products will meet its specifications. There is no warranty of merchantability of fitness for use, nor any other express or implied warranties. The user's exclusive remedy and Goodwin Refractory Services Ltd's sole liability is limited to refund of the purchase price or replacement of any product shown to be otherwise than as warranted. Goodwin Refractory Services Ltd will not be liable for incidental or consequential damages of any kind.

CASTALDO silicone jewelry molding rubber is intended for professional use only by persons familiar with jewelry casting techniques.
We are not responsible for misuse of our products or their use in conjunction with unsafe or improperly maintained equipment or for uses other than intended as mold making material.


Castaldo Silicone Molding Rubber is soft and pliable, with a consistency like putty or molding clay.

Mold frame packing with Castaldo Silicone Molding Rubber is fast, easy and requires no tools.

Placing and embedding the model exactly as you want it is simple.

Curing Castaldo Slicone Jewelry Molding Rubber Molds involves no mixing, limited working times or de-bubblizing. Simply put it in your vulcanizer at 330°-150°F (165°-177°C) for 15 minutes per 1/4 inch (6mm).

Castaldo Silicone Jewelry Molding Rubber Molds are easy to cut, reducing hand fatigue and increasing control. Users say they "Cut like butter".

Parting lines are easily controlled and corrected by hand when used with the powder separation technique.

Finished molds can be simple or complex with cores, straight plugs or even spiral plugs. Castaldo Silicone Jewelry Rubber Molds are strong and tear resistant and can last for years and years.