Was: Annealing pan and pomice for argentium?
It [solderite board] would also work fine as the backing for cuttlebone casting if supplies are limited and one didn't need the texture from the cuttlebone on each side of the casting. I have also used a brick and/or charcoal, each wired to the carved cuttlebone as backing.
I’ve also used plain old gypsum wall board scraps obtained free from
Home Depot as a backer for cuttlebone. Taught my Girl Scouts simple
casting by using two pieces of wall board and carving one or both
sides. You do have to remove off the paper first. One of my students
recently brought me a bucket full of cut-offs of another wall board
type material that he said is used in bathrooms. It has no paper on
either side. Works great. I just use masking tape to attach the wall
board and cuttle fish half together and prop the package up between
some fire bricks. During the pour any extra metal just gets poured
onto the fire brick and is easilty recovered, unlike embedding the
cuttlebone in a bucket of sand and trying to separate extra metal
from the sand.