In a kiln when firing glass, what are the benefits to using Alumina hydrate as opposed to Calcium Carbonate?

In brief, I will be operating an electric kiln, used for the purpose of melting glass.

If fired directly on the kiln shelves, the melted glass would
stick to the shelves. A material is needed to keep the glass
from doing so.

Originally I had planned to use Calcium Carbonate, which is easily found, inexpensive and according to the material safety data sheet, the only health issue would be snorting or inhaling the material.

Some have suggested the calcium carbonate may outgass, which to my understanding is basically putting off gasses. With proper ventilation, what would the benefits of using Alumina Hydrate, which costs about $50.00 per pound as opposed to $3.60 per pound for calcium carbonate?

Many thanks for any assistance,
Karen Marie