Lee, I looked into lost foam casting some time ago. The ceramic paint is sold by foundry supply companies and maybe some pottery supply companies. The big advantage is it's strength, according to the foundry I visited. Also, it removes easily. Did you notice that the plastic foam ended up in the sand? It seems likely that most fumes would also be captured by the sand. The vaporised plastic would be cooled rapidly by the sand. Do you have a pottery supply near you? They sell kiln wash (I think that's what they call it) which is a coating that is painted on the inside of a kiln to protect it. It has a small particle size and so would give a better finish to your part. ERS