Overview: Separating THCA and terpene fraction via evaporation crystallization
Author Berkovitz with DIY Diamond Miner
Example of Erich’s end product
Pour Off: After running very cold solvent at a 10:1 ratio, recover most of your solvent as usual. When you have about 1000ml of solvent left, pour your solution into your pre-chilled vessel/s of choice ⅔ of the way full.
Cold Crash: So I’m not sure exactly how much the cold crash actually helps, but it looks really cool. This step happens right after your pour-off before any solvent gets evaporated. Place your mason jar or diamond miner in a dry ice slurry or lab freezer for 1-2 days. You should have white, spherical crystals blooming on the sides of the jar. You will then let the jar/miner return to room temp, and your crystals will melt. This should help seed your solution and increase crystal growth and speed. Adding nitrogen pressure should keep your crystal layer on the bottom of your jar/miner. Without pressure, your seeds may float to the top and negate the benefits of the cold crash.
Saturation Point: This seems to be the most important factor. After your cold crash you will evaporate about half of your remaining solvent, until it becomes viscous. THCA crashes out of solution when the % of THCA is at or above the saturation point of the solution. You can reduce solubility by evaporation until solubility is reduced to a point where diamonds start to nucleate then grow. (Think growing sugar crystals or evaporating salt from sea-water.) Your solution should start to look a bit thick when you cap it, almost like a syrup.
Seeding & nucleation: Ideally the step above will help seed your solution. If not you can throw some pre-existing THCA crystals into your solution. Make sure enough solvent has evaporated before you do this or you’ll just dissolve a good diamond. This seed will act as a nucleation point. You don’t want to try to force your diamonds to crash by agitation as this will create too many points of nucleation and you will get sugar, or at best, sand. I’ve heard of people laser etching the bottom plate of their diamond miner for nucleation points. Not sure how well it works, but I like the idea.
Temperature: Most of the year I do my initial evap at room temperature – low and slow. Then it goes into the vac oven for 1-2 weeks at relatively low temperature. THCA diamonds seem to grow best around 27c-30c after their initial crash. It’s important that the lid of your jar is on snuggly or you won’t be able to build pressure and all your solvent will evaporate.
Vacuum: NOPE. Don’t do it. If you apply a vacuum, you will make a mess and create sugar.
Miners vs Jars (Pressure): Diamonds are most often grown in mason jars. This is because jars are inexpensive, small, and transparent. However, some processors will choose to grow diamonds in a ‘diamond miner’. They do this for a few reasons. One is because mason jars are made out of glass so they can break. The second is because pressure is an important variable in this process and much harder to control in a mason jar. Some people are under the impression that crystals grow faster under pressure. What’s actually happening is the pressure is keeping the solvent from evaporating and you’re able to pause the solution at the aforementioned saturation point. If you have too much solvent you won’t crash, and if you evaporate too much solvent off your solution will be too viscous to crash and eventually just become a homogenous concentrate. Just like being under vacuum will decrease the boiling point of a solvent adding pressure will raise the boiling point. When using a diamond miner you can add pressure with CO2 or N2, with a mason jar you’re basically limited to adding more butane unless you rig a custom lid with a valve, gauge and/or pressure relief valve. For the best of both worlds, you can put multiple jars in a pressure canner or pressure paint vessel with no lids. You’ll need to be patient as you can’t see in.
Filtration Media and PH: Filtration media seems to expedite crystal growth. This may happen for a few reasons. The first being that the filtration media is removing lots of impurities, lipids, waxes, etc which results in a higher purity solution which lends itself to more rapid crystallization. The second factor is that some filtration media are acidic which seems to promote more rapid crystallization.
Collecting your diamonds: So you’ve got diamonds and sauce and need to separate them? The easiest way to go about this is simply flipping your vessel upside down over a pyrex pan to catch the terpene fraction and a colander to catch any crystals that fall out. Usually, after this step, you will have a patty of crystals at the bottom of your mason jar or diamond miner. This is one of those times a diamond miner comes in handy. You can remove the bottom and BOOM you’ve got crystals on a platter ready to wash or dab. If you used a mason jar, well, grab a pick because you’ve got to go mine those diamonds yourself.
200 gram plus harvest
A cold crash I did in a diamond miner I built with Carla Kay and the subsequent patty of crystals we pulled out.
Washing Diamonds: There are a few ways to go about this. Wash with a cold alkane e.g pentane, hexane, heptane, or spin in a centrifuge. My favorite is to gravity drain your sauce in a colander and leave them a little dirty, because, you know, terps… I call them dirty diamonds because they’re unwashed.
If the diamonds are stuck in the jar pretty tight you can flip your jar over in the vac oven and drain most of the remaining sauce off your diamonds and get a pretty nice looking product without washing your rocks.
Dirty Diamonds aka “the great unwashed.”
More Dirty Diamonds
Let the rigorous testing begin!!
Shoutouts: OTSS (Only the strong sauce tek) probably the first people to share a solid diamond tek, J12 (The diamond king),
-Freeze your jars ahead of time, pouring into warm jars will cause violent boiling.
-This is strain-dependent. Not all cultivars crash the same. If you have mixed results don’t be too hard on yourself, try it again with different material.
-Don’t pay too much for a diamond miner. It’s just a pressure vessel. Cascade sells this for $1400 and it’s basically a sightglass with 3 tri-clamps and little feet welded on at the bottom, and Summit has this glass one for $2100!
There are plenty of pre-assembled diamond miners available on the market for under $400 and you can put one together for about $250.
Example: Prices from BVV
6”x2” Shatter Platter (Bottom) : $50
6” Lid with 3 ports and sightglass: $100
6” High pressure tri-clamp :$38
1.5” tri clamp: $13
6” gasket: $13
1.5” gasket: $1
Ball Valve: $15
If you want it bigger, just add more spools in the middle.
Here is the lab analysis for a run of Burmese Kush grown by OMMP grower PhattyGanja back when we had our shop licensed for OMMP processing.
Burmese Kush Lab analysis
The following are some more cold crash pictures showing the crystals forming on the sight glass walls:
Cold Crash crystal formation
More Cold Crash crystals