I've found that if it starts to wax up just maintain the temp you have & leave under vac for awhile...how long is up to you but crumble as you call it, I call it honeycomb, is just wax that's been a bit more vac-ed... starts to look like a moon rock or asteroid after awhile & I believe this is what you are trying to make(as we all are)...I've never got it to look exactly like twitches avi but close: