CMC Vs Gum Arabic
I’ve tried them all! CMC, kelp starch, Gum Arabic, corn starch, Potato starch and several others. Basically the CMC works better than most and as well as any. They are all vegetable starches.
CMC is also a cooking and baking addative, so no problem with toxicity (non that I know of with any of the starches)
CMCs big advantage is cost. You can buy it for $3 or $4 per pound of powder at any pottery supply house. That is a almost s lifetime supply for most users.
I’ve taught Glass Clay for 3 years now and have 2 examples on this site. It is an incredibly flexible and enjoyable material to work with. On my website I have a whole page dedicated to Glass Clay examples.
Glass Classes: kaiserglass.com/classes.html