Cup Test

Last modified by Hypno Harem on 2022/07/19 19:17

A cup test is performed to remove variables and isolate the source of a cure issue. Smooth-On has an item in their FAQ about it HERE

Cure inhibition can come from many sources. Contamination in a mold, exposed resin on a master, touching a master with dirty hands, cleaning a mold with low-quality rubbing alcohol, pigments, mixing containers, bad silicone batches, poorly mixed silicone, incompatible mold materials. The list is long, but it can be cut in half by performing a cup test. 

Performing a Cup test

1. Mix a small <100ml batch of silicone as you would normally for the toy

2. Degas as normal

3. Pour into a disposable polyethylene cup (clear plastic cup or red solo cup). Do not use PVC or Styrofoam as this can become its own source of inhibition

4. Allow to cure as normal

5. Remove silicone puck from cup and check for cure inhibition

If cure inhibition is not found, then the pigments, additives, mixing, and degas are not a source of cure inhibition.

When should I perform a cup test?

  • Before using new pigments and powders (retain cup test as color swatches)
  • Before adding new modifiers like Slacker, Slide STD, or Thivex to your process
  • Whenever you see an issue with cure inhibition in a toy and the cause is not obvious
  • Before using silicone that has been stored for >1 month (checks that remixing was adequate)