Part of the process
Choose your resin
UV resin cures in minutes under a lamp but only in thin layers. Two-part epoxy takes a day or more and comes as coating, casting and deep pour resin, each with its own depth limit per layer.
- UV resin
- layers of about 2 to 3 mm, minutes under a lamp
- Coating epoxy
- about 1/8 in (3 mm) per layer
There are two families. UV resin is one liquid that hardens in minutes under a UV light, but only where the light reaches, so it suits jewelry, bezels and thin coats on clay. Epoxy resin is two parts, resin and hardener, that cure on their own over a day or more, and it fills molds that light could never cure through. UV resin vs epoxy resin compares them side by side.
Epoxy comes in three kinds, and the difference is how deep one layer may be. Coating or art resin is thick and self-levels to about 1/8 inch. Casting resin is thinner and takes up to about 3/8 inch in one pour. Deep pour resin is thinner still and slow, for 1 to 2 inches at a time. Pour any of them deeper than the label allows and the heat of the cure causes bubbles, cracks and yellowing. See casting resin vs coating resin.
Pick the resin by the deepest part of your mold, then read the label for three numbers: the mix ratio, the working time and the depth per layer. Everything later depends on those. Resin casting powder, sold next to resin for the same silicone molds, is a different material: a plaster-type powder mixed with water that sets opaque white. How to use resin casting powder covers it.
Common mistakes at this stage
- Buying coating resin for a deep mold and pouring it in one go.
- Expecting UV resin to cure through a thick or opaque piece.
- Choosing by bottle size before checking the depth per layer on the label.