by Ed Rosenthal
Photo: David Downs
Some go as low as 68°F (20°C) for strains that have the finished texture of sticky yet flexible tree sap. Some strains’ finishing texture will be a tough sap that snaps if you pull it. They need heat of 85°F–100°F (29°C–38°C), versus 95°F–115°F (35°C–46°C) for strains that turn into good, solid shatter. Some strains’ shatters require up to 125°F (52°C) for five to ten minutes for viscosity’s sake, but anything over 115°F–120°F (46°C–49°C) causes most material to budder. (For more info, see Buddering below.) For a basic crumble wax, place the goopy BHO solution in a vac oven set to -600 mm Hg at 80°F–85°F (27°C–29°C) overnight.
This finished shatter will crack or pull and snap at room temperature, is bone-dry, and is see-through with no impurities.
Photo: David Downs
Flush fresh air through the system every half hour and oven-vac for four or five hours until the slab looks settled.
Take the slab out and let it sit and settle for 20 or 30 minutes, but keep the oven on.
Place your slab-covered parchment paper on a cool surface, and pull the edge of the parchment paper down over the edge of the table. You want to see the shatter separate from the parchment paper. If it’s sappy, lower the oven temp to 70°F (21°C) or 80°F (27°C) and give it four more hours in the vacuum oven. If it’s stable, put on powderless silicone gloves, and flip the slab. Consolidate edge oil into the main body by folding it onto the top.
Flip the patty every 12 hours, because pockets of butane get trapped between the bottom of the patty and the parchment paper. Check to make sure the heat is transferring through the whole resin.
Repeat this gentle heat-and-pressure-purging process three or four times over a couple of days.
The low pressure and slight heat over a long period of time results in an amber-colored, transparent, crystalline, amorphous solid. It should be brittle, or at least pull and snap at room temperature.
You know you’re done when you see very little slab activity in the vac oven, and it tests well below the 5,000 ppm threshold. Send a sample out to a lab to test it.
Buddering
If the shatter turns from clear to opaque, a process called buddering has occurred. The process is a one-way street. Once a shatter budders it must go through a complex process to get it back to true shatter. (See “Knottyy’s BHO Budder to Shatter Tutorial” on YouTube.)
Many strains including Blue Dream and Grand Daddy Purple are notorious for auto-buddering—that is, the waxes in the solution hydrate and nucleate, or clump up. (OGs and Blue Dream tend to have a lot of wax in them.) Despite the most careful efforts to create shatter, the resin turns opaque during purging. At that point, it’s best to make honeycomb.
BHO of this consistency is called wax, budder, crumble, etc.
Photo: David Downs
BHO Shatter.
Photo: Steep Hill Halent
Shatter turns to budder when heated too long, and even the finest shatter turns to budder eventually during storage. It’s thought that the process of auto-buddering occurs when heavier fats and lipids precipitate out of the solution with the rest of the cannabinoid/terpene matrix. Buddering often starts in one corner of the resin patty, and spreads across the entire piece.
If buddering has occurred, you can heat the resin to a honeycomb consistency, whip it into budder, or heat it down to oil.
MIXING SOLVENTS
Mixing solvents slightly changes the mix’s solubility, making it better suited to extracting specific terpenes in a particular strain.
Butane is a very simple organic molecule consisting of a chain of 4 carbon atoms with hydrogen atoms attached to them. Shortening or increasing the carbon chain yields propane (3 carbon atoms), and ethane (2), and methane (1), as well as pentane (5) and hexane (6). You can adjust the amount of n-butane in conjunction with its closest relatives—isobutane, propane, and pentane—to best suit the strain or desired consistency.
For example, n-butane has a slight water solubility. At 68°F (20°C), it is 0.0325% soluble, not 0%, so it’s still soluble enough to pick up undesirable water solubles. One liter of n-butane can dissolve 32.5 ml of water. With water comes water solubles like chlorophyll and plant alkaloids, which taste bad. Pentane has zero water solubility.
BHO Shatter.
Photo: Steep Hill Halent
Lamb’s Bread Shatter.
Photo: Nadim Sabella Photography
Mesozoic Amber Shatter.
Photo: Nadim Sabella Photography
BHO Shatter.
Photo: Steep Hill Halent
Leaving shatter in the vac oven at 120°F–130°F (49°C–54°C) for several hours results in a honeycomb-like wafer. More butane is removed when the temperature is raised and the pressure lowered, but it also removes more terpenes.
More heat and low pressure cause the honeycomb to melt back down to an overpurged, condensed plant oil.
BUTANE EXTRACTS—THE OPEN-ENDED METHOD
Equipment
•Butane canisters (one canister per ounce)
•Thick-gauge, 2"-wide, 25"-long Pyrex glass or stainless steel extraction tubes (stainless steel is stronger; Pyrex is easier to see what’s going on inside the tube)
•Coffee filters (unbleached)
•Source plant material (trichome-rich, fresh-cured, cleaned of debris, chopped up)
•Large Pyrex casserole dishes for catching trays for solution
•Parchment paper
•Safety glasses
•Organic vapor-rated gas mask
•Large fan
•Hot plate
•Flame- and cold-resistant gloves
•Implements: dishes, trays, scrapers, jars
•Powderless latex gloves
•Laser thermometer
•Chemical fire extinguisher
•Fireproof suit
Obtaining Butane
Open-ended extraction is far less efficient (and hence, more expensive) than closed-loop. Since it doesn’t reuse butane, it requires about 80 normal-sized canisters to extract from about five pounds of plant material (versus the equivalent of 32 canisters in closed-loop). If you cannot avoid cans of butane lighter fluid select a 5X or above quality fluid. There are many brands marketed for just this purpose. Stay away from Ronson and stove fuels—they contain poisonous additives. (See Tips/Reminders below.)
Preparation
Set up your extractor in a well-ventilated area during a cool, dry day.
Use very dry plant material. However, drying also sacrifices terpenes that are volatile at low temperatures.
Tightly affix filters to the bottom of the tube using hose clamps. Don’t overtighten, as you can crack Pyrex.
Add chopped trim and buds to the trim tube. Some people use small, untrimmed, pea-sized nugs. Use a wooden dowel to pack it firm and uniform but not tight. An overpacked glass tube can shatter under pressure, or cause the bottom filter to pop off, blowing cannabis into the BHO.
Affix the canister discharge cap to the top of the tube. Alternatively, some open extraction tubes terminate in a hole that fits butane canisters, so you don’t need a cap.
Set the tube up vertically with the filtered end at the bottom and the canister discharge cap end at the top.
Place a large Pyrex dish underneath the tube.
Position the fan so it blows fresh air at the extractor and worker, and pushes gas away from them.
Blasting
Discharge individual canisters into the hole in the egg-shaped top of the tube. Pressurized liquid butane will run through the material and eventually begin seeping through the filter and pooling in the Pyrex tray.
The tube will get cold during extraction and attract moisture from the air. This dew can freeze and break a glass tube. Stainless steel is a better choice. It’s stronger and will not break.
The Pyrex tray of liquid solution will also get very cold. Take care to prevent dust or debris from blowing into the tray.
Mean Skreenz filters are made
with chemical- and solvent-resistant material for use in the extraction of essential oils.
Photo: Ed Rosenthal
Purging/Achieving Different Consistencies/Decarboxylating
Purging
You can quickly and easily dewax the solution using dry ice. (See Winterizing below.)
If left outside in a well-ventilated area for a day to air purge, you’ll be left with a waxy, yellow concentrate.
After dewaxing, speed up the purging process by using a hot plate set to 90°F–100°F (32°C–38°C) with a double boiler, in a well-ventilated area accompanied by a fan, to gently warm the solution. The BHO boils as the solvent quickly evaporates.
Be careful. This is the most dangerous stage of open-ended blasting. The vast majority of liquid butane evaporates into the atmosphere and travels along the ground looking for a spark to explode. Exercise maximum caution when double boiling. Also, you can use a breathable, water-resistant screen of some type over the Pyrex dish at this stage to keep dirt, dust, and debris from blowing into your solution from the fan.
It takes between 15 minutes to an hour to purge most of the butane out of the BHO using a hot plate and double boiler. The end material should have the consistency of maple syrup, and will be ready for the vacuum oven. If you leave it on the hot plate for too long it will get drier, and you’ll end up with a mixture of budder and shatter in the tray.
A hot plate is also warm enough to burn off terpenes.
For a more thorough, professional purging, use a vacuum oven. (See Closed-Loop Method above.)
Variations
Purging
People use different combinations of temperature and pressure of the vacuum oven which affect the consistency.
A collection of dried waxes separated from their solution by winterization.
Photo: David Downs
This Buchner for an open-ended extraction consists of a broad funnel fitted with a stone filter and a flask underneath.
Photo: David Downs
Winterizing
Winterizing liquid solutions removes the wax content so the material develops a shatter consistency. Winterizing involves freezing the raw solution for 36 to 40 hours. The cold temperature causes the plant wax to precipitate and collect on the surface where it can be skimmed out. Winterizing shatter results in a much smoother smoke, because the heavy waxes are gone. Separated out, the wax can be used to make a candle.
You can winterize an open-loop system with dry ice or a Buchner—a glass beaker funnel fitted with a special 1.5-micron pumice stone that’s super-chilled. For dry ice, place slabs of ice underneath the Pyrex dish used to catch the raw solution during extraction. The cold from the dry ice will cause the waxes and lipids to sink to the bottom of the Pyrex and congeal on it. Dump the remaining dewaxed solution into a clean Pyrex dish. For a Buchner, the raw solution is poured into the Buchner funnel and a hand pump is used to pull the BHO through the cold stone matrix, which holds on to the waxes while the rest of the solution falls through into the Erlenmeyer flask.
Some recapture units offer in-line winterization, which is a special stage in the process where the raw solution sits in a steel drum surrounded by a layer of dry ice. The dry ice chills the drum, and the waxes in the BHO collect on its sides.
Winterizing can be very dangerous. Do not simply stick a mason jar full of liquid butane solution in the freezer—you are making a bomb. The butane will evaporate out of the jar, flow down and out of the freezer until it finds a spark and explodes. Some professionals collect the raw solution in a stainless steel pressure pot, add in more liquid butane, and place it in an explosion-proof freezer that is specially well-ventilated. We repeat: Placing butane in a freezer can result in a massive explosion.
Decarboxylation
If the BHO is to be used in edibles, it needs to be decarboxylated because THCA’s COOH carboxyl group makes it unable to pass the blood-brain barrier.
The COOH breaks apart from the THC over time, but you can speed up this process exponentially with heat.
THCA and CBDA decarboxylate into THC and CBD beginning at 222°F (106°C).
It’s super easy to decarboxylate purged BHO—just double boil it in a water bath set to above 222°F (106°C). When the BHO gets warm enough it’ll suddenly start producing CO2 bubbles. Stir the BHO. When the bubbles suddenly start to taper off significantly, the BHO is mostly decarboxylated.
The wrinkle is, the same heat that turns THCA into THC also turns THC into cannabinol (CBN), which is more sedative than THC. When THCA is 70% decarboxylated into THC, the rate of THC-to-CBN production eclipses the rate of decarboxylation from THCA to THC.
So, when the bubble formation suddenly tapers off, the oil has reached the maximum head effect. Further heat makes it more sedative.
BHO that is going to be smoked or vaped does not need to be decarboxylated. The lighter or nail will take care of that instantly.
Tips/Reminders
•Water is the enemy of solvent extraction. Water is the most universal of solvents and it is very polar. It has spare electrons that interact with anything that is polar. Trichomes are nonpolar due to their waxy, oily covering. THCA is slightly polar, and bound up in the wax. Water in the butane extractor or plant material raises the polarity of the system, decreasing the solubility of the solvent and preventing butane from doing its job. Keep water out of the extraction system, and run the process in a room with very low humidity.
•High heat is an enemy. Even low heat can make the delicate flavors and smells of cannabis disappear, and very high temperatures degrade THC. Dissolved hash will also darken, leading to a far less desirable end result. Work in a cool, dry room, and do not overheat during purging. Terpenes begin to burn off at 68°F (20°C).
•Test the vacuum oven by pulling it down to the lowest it will go and waiting an hour. If the vacuum is lost it means there is a leak.
•Make sure the air pressure gauges on the vacuum oven are in good working order.
•If you pull a vacuum too fast on a resin that is too liquid the violent boiling can make a mess. Bring the pressure down slowly to keep the resin calm.
•Raise the temperature slowly on the vacuum oven or you can easily overshoot it and burn the resin.
•Be careful with extreme vacuum pressure. A super-strong vacuum pump is not needed. At 99.999% vacuum (.01 Torr), THC boils at 23°F (-5°C). Don’t go below a 99.2% vacuum or 1.5 Torr (1500 microns).
•Cannabis is just like any other produce; it browns as it ages. That includes the trichomes or any extract made from it. Fresher is always better.
•For best taste, fresh, dried material is ideal. Older material will just taste like hash. The degree of drying and curing is critical to maintain maximum flavor and taste. BHO from buds is called a “nug run” and tastes better than trim.
•If you can’t get instrument-grade n-butane, use butane advertised in appropriate magazines and in appropriate stores, but do some homework. Check out the MSDS (material safety data sheet) from the specific manufacturer, showing the product’s contents on the Internet. Avoid anything with mercap or Butadiene. Ingredients that comprise less than 1% of the fluid do not appear on material safety data sheets. If the MSDS looks all right, spray a five-second burst on a mirror or clean glass pane and let it completely evaporate. Check for residue. Smell it for mercaps—you can’t miss them.
•Consumer brands Colibri, King, Lucienne, Newport, and Vector—4X or higher—work well. The X refers to how pure the product is in terms of how much paraffin wax has been taken out of the gas.
•Do not use Poly Vinyl Chloride (PVC), Acrylonitrile Butadiene Styrene (ABS), or Low Density Poly Ethylene (LDPE) in your extraction equipment, as the butane leaches chemicals out of the plastic, and they will end up in the hash. Stainless steel is best. Borosilicate glass may break in cold, wet weather.
•Watch your ambient humidity. Butane boils at room temperature, pulling heat from the air, and getting very cold, causing condensation of ambient humidit
y. This adds water to your solution and water is the enemy.
•Use filters carefully. They are a critical bottleneck in both open and closed-loop extraction. Clean reusable filters every time before a new run. Don’t use too many disposable filters. Both dirty reusable filters and too many disposable filters can clog up your system, and significantly delay or even ruin the extraction process.
•Cleanliness and orderliness are mandatory in extraction. Look around your room right now. Make sure the workspace is orderly and clean. Make sure all the tools you might need are in place.
•Be prepared to encounter setbacks, especially in pursuit of excellence. Slightly tweaking a process or trying a new one may create problems. Even dialed-in systems go haywire from equipment malfunction. Murphy’s Law applies.
Royal Kush Shatter.
Photo: Nadim Sabella Photography
Curing/Pressing/Storage
Cure fresh shatter in a cool, dry room at 40°F–60°F (4°C–16°C) with under 30% humidity for at least a day. The curing process can lock in the shatter and prevent auto-buddering during storage.
BHO does not need to be pressed and is best stored on parchment paper in a sealed glass jar in a cool, dark place where it will not be exposed to humidity.
Due to their nonstick surface, silicone containers are often used for storage of BHO.
Headband CO2 Shatter.
Photo: Nadim Sabella Photography
Chapter 8.
CO2 Extracts—
Making Concentrates
Marijuana extraction technology is leapfrogging into the future. That future is largely considered to belong to carbon dioxide, which normally exists as 0.039% of the air in our atmosphere.