Instructions for Use

Castaldo® Rapido™ Silicone Molding Rubber makes tough, strong, long lasting PRODUCTION molds very rapidly.

Castaldo Rapido Silicone Molding Rubber should be vulcanized at 93˚ C/ 200˚F for 5 minutes per section but in no case for less than 9 minutes. This is the minimum vulcanizing time.

Typical vulcanizing times are thus:

Mold Size

Vulcanizing Time

6 mm / ¼” mold

9 minutes

12 mm / ½” mold

10 minutes

19 mm / 3/4” mold

15 minutes

25 mm / 1” mold

20 minutes

Most of the tools and techniques for using Rapido are similar to those used with our Super High Strength™, Econosil® and other silicone molding rubbers. A copy of the instructions for those products is enclosed.

PLEASE NOTE: Because Castaldo Rapido vulcanizes at a relatively low temperature it does not have the extended storage life of many of our other compounds. Castaldo Rapido may SELF-VULCANIZE DURING STORAGE at high summer temperatures or in very warm climates.

During the summer months or in very warm climates the rubber should be kept in cold storage such as in a refrigerator or in a constantly air-conditioned room, but NOT below 0˚ C/ 32˚F. You may want to avoid storing more Rapido rubber than is needed for immediate use. Similarly, long ocean freight shipments during very warm periods may effect the rubber. Possible solutions might be to avoid such shipments entirely during the summer months or ship smaller quantities via air freight.
Finished molds require no mold release spray. Wax patterns release easily because the rubber already contains anti-stick compounds.

The cure system used with Castaldo Rapido Silicone Molding Rubber is NOT compatible with the cure system used with our natural rubber compounds such as White Label®, Gold Label®, Titanium Label™ or No Shrink Pink® . 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. A more practical approach may be to devote certain mold frames, mold plates, etc. solely to the use of silicone rubber compounds.

Castaldo Rapido Silicone Molding Rubber CANNOT be mixed in the same mold with Castaldo White Label, Gold Label, Titanium Label or No Shrink Pink rubbers for the above reason and also because the two types of rubber will not bond.

Castaldo Rapido Silicone Molding Rubber is compatible with all mold making techniques including mold cutting and powder and cream separation molds. It is particularly adaptable to the powder and cream separation processes since the parting line is so easily controlled. For patterns strong enough to resist some pressure, merely push the model into the unvulcanized 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.

Castaldo Rapido Silicone Molding Rubber is strong, but not as strong as natural rubber compounds such as White Label, Gold Label, Titanium Label and No Shrink Pink. Remember to pull GENTLY while cutting the mold because of this difference.

Castaldo Rapido Silicone Molding Rubber CANNOT be burned in the usual manner to add sprues or correct details.

CAUTION: Vapors given off during vulcanization may produce temporary eye, nose and throat irritation in susceptible individuals. Use with adequate ventilation. See Safety Data Sheet for further details.

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 Rapido Silicone 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 jewelry casting mold making material.