The Filter Tower

My cannabis oil is made by drying harvested plants, soaking them in virtually pure (95% or better) ethyl alcohol, filtering all the plant solids out, then cooking off the alcohol. What’s left is highly potent, highly sticky oil. But to get the best oil you have to put in serious time at the filtering stage.

Filtering involves slowly pouring the infused alcohol through a coffee filter. (Or a kitchen-grade oil filter, but it’s much easier to find coffee filters.) This take a really long time, and it gets deeply boring? However, I have a trick that speeds up this boring stage dramatically.

I took an Ikea ‘Billy’ CD tower and gave it a new lease of life. Well, who uses CDs these days?

I drilled holes in four of the shelves and slotted plastic funnels with coffee filters inside each one. I raided a wine making kit for a length of plastic siphon tubing and a basic flow control tap, then put a large Kilner jar full of the cloudy alcohol ‘wash’ at the top and an empty jar below the last funnel.

Siphoning the alcohol wash through four filters on one session.

Getting the siphon started was a challenge – I ended up standing on a chair to do it. But then it worked like a dream: a slow controlled trickle into the first funnel, which trickled it on down to the next, then two more, before finishing safely in the jar at the bottom. This is the first time I’ve been able to get the flow right and then walk away and get on with other things. Filtering four times used to be something I thought I probably should do… but life’s too short. Now? Four-stage filtering in one go, virtually as fast as a single filter.

The alcohol wash is beautifully clear after filtering, which means the final oil is cleaner and tastes better. My next step is to use a smaller tube, which will make siphoning easier.

Further development? I’d like to work out how to do this at very low temperatures for an even more pure result – but that’s for another post.

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