The Earth Clay Wall separates off the OIL Based Clay Sculpture much easier than an Oil Based Clay Wall would. Attaching the first slab of retaining wall clay. The retaining wall finished. Before you slap on the liquid plaster you'll need to protect the clay with a release agent. I use vaseline for these low quality jobs.
Professionals use a silicone agent.
Two light coats of Cystal Clear Acrylic paitn does a good job too. Actually most mask makers use Clear Acrylic paint for most of their latex mask molds. It works well and is very cost effective. Here's the bowl of plaster and the sculpture before the plastering. Have a large plastic drop cloth on the floor, liquid plaster is very messy.