I'm not sure. You'd have to try it I guess on a sacrificial piece of metal.
I have heard of people making it from baking soda which is sodium bicarbonate. I'm not sure the process but I believe if you heat up sodium bicarbonate it will become sodium carbonate.
I'm sure YouTube might be a good resource as well.
I know in baking, dough rises as the bicarbonate becomes carbonate.
Good luck with the anvil resto.