A new enameling kiln is the most important investment an enamelist will make. It pretty simple to be sure it will have a long life by preventing the enamels from sticking to the floor of the kiln. by using kiln wash.
You can purchase this from me on my kiln accessories here https://croftkilns.com/accessories/kiln-wash/
Very little is needed. Add water, to the consistence of thin pancake mix. The firebrick will absorb the solution quickly, thus you need it on the wet side. Apply first to the kiln floor. From here some artist buy shelf paper, again from your ceramic supplier. Or you can have ceramic shelves that you apply kiln wash.
Let the kiln wash dry over night. I have tried to dry it by heating my kiln only to have it pop off. Over a period of time you will have spilt enamel on the shelf. Just scrape it off and reapply kiln wash dry and with the shelf in place and I am ready to enamel!