I use my friend's vacuum purger..he made it out of an industrial vacuum from harborfreight (120$) attached it to a piece of 1/2 " plexiglass...after spraying into the pan, and letting the butane evaporate, we put the whole pyrex pan into a big thick pot and put the plexi 'lid' on, with rubber gasket...it sucks out so much extra butane that it swells up quite a bit...almost hitting the lid sometimes. It was amazing to see how much was left in what I thought was a 'clean' product.
I'll get pics next time.
I'll get pics next time.