Improving the process

This article is specifically about the Green Oil Machine, a kind of ‘air still’ that is marketed and supported specifically for extracting cannabis oil from buds and leaves. This is what I currently use for producing my medicine. The process involves washing your dried buds/trim/leaves in 190 proof/95% or stronger ethanol (ethyl alcohol), filtering a lot, then ‘cooking’ the alcohol off to leave just the dissolved cannabis oil. This process is explained in detail in the Green Oil Machine page.

The GOM has a basic fan-cooled condensation system in its lid, which recondenses the alcohol vapors as they boil off and sends this through a small tube into your ‘reclaim’ jar or bottle. This reclaims around two-thirds of the alcohol that is used in a batch, which is MUCH better than nothing. But as very high-proof, non-denatured alcohol can be difficult to find in many parts of the world and it’s not exactly cheap anywhere, I wanted to find a way to improve this reclaim percentage.

I tried the old ‘seal the reclaim jar lid better’ approach, using tinfoil, clingfilm and similar things to wrap around the jar opening that collects the alcohol to try and stop the evaporation. While that helps a little bit, there are other things that are actually much more important to address to really improve this reclaim percentage…

  • The alcohol that comes out of the GOM’s own condenser lid is really hot. Totally understandable! But pure alcohol evaporates FAST when it’s hot.
  • The GOM ‘nose’ where the reclaim tube is attached is a kind of open reservoir; the condenser pipe opens into this, and this drains down into the silicone tube.
  • Much of the evaporation happens in this unsealed ‘nose’ so even a perfect seal around the reclaim jar won’t help with that.
  • Some units apparently have carbon filter blocks in this reservoir. The three I’ve seen in real life don’t, and just-distilled alcohol doesn’t need filtering. Anyway, that would slow the trickle-through rate of the hot alcohol and allow more evaporation.

I ran a full GOM last week; four litres of wash. At the end my reclaim percentage was over 95%, a dramatic improvement on the 60-70% at best I’ve had before. Here’s how I did it:

The product

I got hold of a simple ‘Stainless Steel External Cooling Pipe Tube Cooler Brew Distiller Condenser For HomeBrew Brewing‘ from Aliexpress. It can be found elsewhere but this was the cheapest source I could fine. This is a really simple device: just a straight-through stainless steel tube of around 10mm inner diameter, and an outer steel sleeve with in and out tubes on the side. I’ll call it the cooling pipe from now for simplicity.

The process

I took the GOM’s metal nose entirely off. This is held in by friction and a simple tab that clicks into place, so no cutting or breaking is needed. Inside the plastic nose hood cover is the end of the tube from the GOM’s condenser pipe, with a short right-angle silicone hose that directs the liquid down into the metal nose. I attached the cooling pipe to this, ran a hose from the other end to a reclaim jar, and then attached a garden hose to one of the outer sleeve pipes and a hose from the other to a drain.

The results

When I ran the GOM, the moment the first bit of alcohol started to come through its condenser lid I turned on the cold water tap and ran a trickle of cold water through the cooling pipe. The GOM’s outlet got hot as expected from the recondensed alcohol, but the alcohol that came out of the far end of the cooling pipe into the jar was room temperature. This is a drop of around 120°F/65°C!

What this had done is create a CLOSED distillation path with a water-cooled stage, and the result was a dramatic increase in alcohol reclaiming. The cost of the cooling tube was under $20, and the amount it saved easily paid for itself in one full GOM load.



Next steps

My next step will be to cut the front of the GOM’s plastic nose hood off and use a longer heat-resistant silicone hose to connect this cooling pipe. The reclaim results won’t change but it’ll be easier to handle and more robust. This step would invalidate the warranty, but it’s 2+ years old anyway so that’s long gone.

Want to distill your own alcohol? This isn’t just good for running GOM loads of wash without losing so much alcohol, it’s a real benefit if you plan to make your own alcohol. Raising the ABV level by running it through the GOM is very effective, but you’ll be losing around 1/3 of the alcohol each time. Do this and you lose less than 1/20th. Simple, eh?

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.