Silicone rubber molds stick to my
mold plates
Mold Cutting
Sometimes the top and bottom surfaces of vulcanized silicone rubber molds will stick to one or both of the aluminum plates used between the mold frame and the vulcanizer itself.
This is caused by UNDERCURE or INCOMPLETE VULCANIZATION.
CASTALDO silicone rubber molding compounds are designed to vulcanize at 330o F -350o F / 165o - 176o C AS ACTUALLY MEASURED ON THE MOLD PLATES. Do not trust the vulcanizer dials, as they are often WILDLY inaccurate. Even well made vulcanizer heating elements and controls can become faulty over time.
The solution is to calibrate your vulcanizer to achieve the proper temperature. Buy a good quality thermometer and use the following technique:
Place a small block of wood -- about 1/4" to 1/2" (6 to 12 mm) thick--- as a cheap and easy insulator-- on the bottom plate of the vulcanizer after it has heated up for a while. Place the probe of the thermometer on top of it and close the vulcanizer plates gently. Go about your normal business and check the thermometer once in a while, noting the readings. After a few hours, repeat the process, this time with the thermometer under the block of wood.
This way you are isolating the two plates and not measuring the average of the two. It's like the old story of the man with one foot in a bucket of ice water and one foot in a bucket of boiling water-- on average, he's comfortable.
Calibration should be done regularly for best results.
Molds will release easily once you have set your vulcanizer at the proper temperature.
