I started off on closed loop making shatter years ago and didn't have too many issues. This open blast crumble thing is escaping me though. Both of these have been whipped for hours before i started purging. I don't have a vac oven so im using a heat lamp and temp gun and keeping at about 100 most of the time but never over 110. The larger pyrex has been purging about two days and the smaller one about 5 hours. Typically how long does it take to start crumbling and what are the stages of progress it goes through? Do i need to whip it again? Both of them still spark quite a bit when testing for butane.