Skin is both a pour style and a method of cleaning a mold.

Skin/Highlight Pour Style

To create a highlight in a toy, a small amount of one color of silicone is poured into a mold and rolled around to coat the inside. The mold is then placed upside down to drain the excess. Once the skin starts to reach a jelled state but before final cure, a second color is poured in to backfill the mold.

Mold Cleaning

This should only be done on well-seasoned molds! Skins are fragile and may adhere and rip off inside newer molds and those with less mold release.

To clean a mold, mix up a small amount of heavily-pigmented silicone in a contrasting color to the mold material. Pour into the mold and roll around. Invert the mold to drain. Do not allow the silicone to pool in the bottom of the mold or the skin may be hard to pull out and rip. Once skin has reached a jelled state but before final cure, repeat the process to add a second layer. Once fully cured carefully peel the skin out of the mold. A single layer of skin is possible in some molds, and in others three layers may be needed. Generally, the newer the mold and the more complex the geometry, the more layers needed.