thermos is not a person more or less a tool. I still do not advise what you have described.
the thermos method- take a thermos and you are supposed to drill 3 small holes in the lid, one for the tip of the butane can the other 2 for the gas to come out. the thermos "insulated" will stay cold enough that the butane can pool in the thermos. when you empty a can or 2 remove the lid and look inside at the clear liquid this is liquid butane "extremely explosive" now take your material and drop it in the thermos careful it will boil when you add the room temp material to -40 degree butane, now take a coffee filter or 3 and put it over the mouth with the lid off then flip upside down over a pyrex dish the preasure inside from the butane boiling will force the liquid butane through the filter with the oil. so for you instead of a pyrex get a buchner funnel....
you do know that it is not the funnel but the filter that is inside the funnel, most buchner funnels i have seen have huge holes and are meant for you to put a coffee filter in them. the buchner that i have has a 2 to 5 micron ceramic filter in it
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