You will be pleased to note that our FIRM, FLEX and LOW SHRINK GRAY grades all  demonstrate controlled shrink. You will never encounter variations in hardness or shrink with  Akron Jewelry Rubber™ .

Pre-heat your vulcanizer to 310° F (154° C). Periodic checks of temperature calibration is  recommended. Temperature and time may be varied to suit your needs and experience, however,  it is recommended that you not exceed 325° F (163°C) with any natural mold rubber.

Akron Jewelry Rubber™ should be vulcanized at 310° F (154°C)  for 7½ minutes per layer of  rubber.

Remove plastic covers from both sides of rubber.  A good practice is to use stainless steel or  aluminum mold plates which are available inexpensively from any dealer. If you write on the  rubber, slip a small piece of aluminum foil between the rubber and the mold plate to prevent  ink transfer. Pack mold frames fully, taking care to fill undercuts with small pieces of rubber.

It is not necessary in all cases to pack an extra layer of rubber ( 7 pieces in a ¾" frame). If you  use frames with small vent holes, it is a good practice to do so. In any case, you should make  certain that the rubber in your packed frame extends above the surface of the frame.

Be sure that your vulcanizer is up to temperature before inserting packed mold frame.

Tighten vulcanizer by hand and check periodically during the first 5 minutes to ensure that it  remains snug. Do not use excessive pressure as you can damage the model and the vulcanizer.

At the end of an appropriate vulcanization time, remove your mold from the frame and allow to  cool at room temperature until it can be handled comfortably. A ¾" (19mm)  mold will take  about 20 minutes to cool sufficiently. You may also use cold water to cool the mold.

Akron Jewelry Rubber™ provides a somewhat easier release than other products, however  you may find that using our slick™  silicone mold release is helpful if used sparingly. As with        any mold release spray, allow the spray to dry before injecting wax. Used sparingly, drying is  rapid. The wetness you see is the solvent that carries the silicone. The silicone remains in the  mold after the solvents dry. Injecting a mold that is still quite wet can produce less than desired  results.

Finished molds should be stored away from sunlight and heat to preserve their flexibility for  years to come. The uncured shelf life of Akron Jewelry Rubber is 7 years.