My pics seem to be having issues, so I included the URLs too...
Unfortunately, I didn't start with top notch bud. Instead, it was some runts that got pulled out of the grow early and dried/cured with the regular stuff. It as really fluffy/airy, so I didn't break it up too much. It was also pretty dry and didn't want to turn it into powder.
Everything, including all equipment, was frozen in a chest freezer at -15F for several days before starting.
I started with 3 pounds total. About a half pound fit in the 100um screen sitting on the 5 gallon bucket.
https://goo.gl/T1WSA8
Originally, Oakley recommended 1 quart per ounce of pot. The store didn't have that much iso, so I used 2 gallons per pound (1/2 quart per ounce). I get my iso for $30/gallon from a local vendor.
I packed the 100um screen with the pot and poured a half gallon over it, waited one minute, then poured the rest. I let that drain until the dripping stopped. Then I dumped that into a bag and squeezed it out as described in the initial tek. Repeat with remainder of pot.
https://goo.gl/ACYzYj
I noticed that nothing really came out when i squeezed the bag, so I stopped the bag squeeze after the first half pound. I did continue to mash the pot into the screen to try and squeeze out any leftover solvent though. In total, I used 6 gallons of iso and ended up with 4.5 gallons of iso after washing, meaning 1.5 gallons was tossed out with the material.
After everything had been washed, I began filtering. I set up a strainer with large coffee filters. This took awhile. I put the filtered iso back into clean jugs and let that sit for 48 hours at -15F. I then decanted the liquid from the gallon jug into another coffee filter lined strainer for a second filter pass.
https://goo.gl/Oqh7ru
https://goo.gl/WKZMqN
I put the filtered iso into a stainless pot with a lid sitting in an oil bath. I used a temperature controller to keep the temperature of the oil right under the boiling point of the iso, or ~175F at my altitude/pressure. I used a second thermostat to tell me the temperature of the iso in the pot.
https://goo.gl/iuNlCV
https://goo.gl/7zsPLZ (the picture also shows a simple attempt to reclaim some of the iso. Yeah, that didn't work. :/ )
Overall, it took about 9 hours of evaporating and topping off the iso to get it reduced down to about a cup of liquid.
https://goo.gl/S7RDaF
I set up a griddle with a silicone mat so I could pour the iso and evaporate it directly on the silicone mat to minimize loss. I used my infrared thermometer to make sure the temp of the griddle/mat/oil never got above 190-195F. I cooked this until the bubbling mostly stopped, removing the mat from the griddle if necessary to maintain temperature.
https://goo.gl/sJCuha
https://goo.gl/PKrf8R
A m
ovie of the evap process.
A m
ovie of me taking its temperature.
In total, I ended up with 74 grams of oil from ~1300 grams of pot, or about 5.7% by weight.
This is 37 grams, or half of the yield from the run:
https://goo.gl/bIVH0H
https://goo.gl/KCLHnT
I've run smaller amounts of good buds (around an ounce) and had better results (~4-5 grams per ounce of starting material). I'm thinking the reduced yield was probably due to a couple of things:
1) Quality of the pot we started with
2) When running the smaller amounts, *all* of the solvent went over *all* of the material. When running the larger amount, the screen was wider and the solvent was spread around more (see video), so a given area in the screen might only receive *some* of the iso. It might be beneficial to use a tall, narrow column instead of a wide, flat disk for the wash to ensure all of the solvent hits all of the pot. Or, increase contact time by doing a short 30-60 second dunk.
It might be worth trying more solvent and/or re-pouring the solvent over subsequent batches (for 1 pound, pour 2 gallons over the first half pound, reload the screen, then pour that same 2 gallons over the second half pound). Or, wash with an extra 1/2-1 gallon to guarantee you end up with 2 gallons per pound of pot *after* your wash.
Thanks again Oakley for the inspiration. Hope this post helps someone.