The only kiln wash that I know of that has to be reapplied after every use is Hotline Primo. It can be easily brushed out of the mold and reapplied, drying between coats with a hair dryer. Kiln wash does not have to be dried in the kiln. Apply it and let it dry overnight. Most kiln wash (with the exception of Primo) applied to a slumping mold will last through many, many firings before having to be reapplied.