Fast firings and kiln wash
So you are firing very fast and very high. I have missed what glass you are firing but 1800F is -by my conversion – about 180C [324F] higher than needed for all except float. No [blank, blank] wonder your kiln wash is sticking. I don’t know of any kiln wash that would stand up to these temperatures. Generally, the ceramic batt washes are a bit coarser than that made for glass, but are essentially the same composition otherwise.
I wonder what your glass is looking like. A puddle, I guess.
Look at the Bullseye site technote 4
This will tellyou a lot about how glass reacts to heat. Also look at the tutorials on this site for information on firing.