Noah,

What brand BCB are you using and how old has it been sitting? Does it
flow very slowly when you are dispensing it? I was
having the same problem spinning on a silicon wafer sample and it turned
out to be that the BCB had been sitting on the dispense bottle for some
time.  As soon as I got a new batch of BCB the problem was solved.

hope this helps,

Lester Lopez
University of South Florida