This is a guest post contributed by Slyng's chemist friend Kenneth F. He's working in his own lab in Denver, CO.
A cannabis concentrate is a product which has been extracted from the cannabis plant by any of a variety of techniques. So what is the difference between all of them? The short answer is consistency or texture.
As a chemist I have been trying to answer this question since I first joined this industry. The biggest difference I have been able to find has to do with the extraction technique. Once a concentrate has been produced it is next to impossible to change it without losing something, more on this later. The extraction techniques each have their own advantages or disadvantages, but at the end of the day the only difference between various concentrates is the consistency and or texture.
They way I have found easiest to distinguish between concentrates is to start first with the extraction technique. For this first comparison I will be assuming the extraction technique is starting with raw cannabis plant material.
The most basic variable in extractions is whether or not a solvent is used for the extraction.
Solventless extractions utilize heat, pressure or neither. The earliest forms of concentrates have been around for centuries. Keif is just collected trichromes (crystals) from cured cannabis material.
This is the most natural concentrate since nothing other than some physical agitation has been used to collect the product.
The other natural concentrate is what is known as hash or hash oil, this is usually collected by rubbing cured cannabis between one's hands then rubbing sticky hands together to produce a ball of concentrate.
Again I find this a fairly natural technique for concentrating the active compounds in cannabis, and has been used for centuries in the Middle East.
A heat press can produce what is commonly referred to, in Colorado, as rosin or live resin, the first starts with cured cannabis material while the second starts with fresh cut and usually flash frozen cannabis material.
Solvent extractions rely solely on the solubilities of extractable components within the cannabis plant in the solvent utilized in the process. So far I have found the following solvents used with the industry; water, ethanol, butane/propane (hydrocarbon) and CO2.
Bubble hash is a well established water extraction technique, it employs the properties of solubilities and densities to separate the crystalline material from cured plant material.
The cannabinoids are less dense and insoluble in water so they rise to the top of the water while the plant material usually sinks or can be pressed to the bottom of the extraction vessel.
Ethanol extractions have been done to extract and identify compounds in a variety of flora for decades. For a long time, ethanol extraction was how we collected vanilla flavor, and is still used to collect aromas from herbs and spices.
The process is fairly simple, the real challenge is getting the right ethanol grade to do professional extractions. Plant material is placed in a vessel with excess ethanol, some apply heat others prefer to allow time to do the work. The plant material is then separated and the ethanol is evaporated. Ethanol is not highly selective as an extraction solvent, so the produced oil tends to have a more green tint to it, and I have found is has a “plantier” taste. Depending on the evaporation conditions of the solvent, the disadvantage to using ethanol, is that you can lose a fair bit of terpenes and flavonoids is this process.
Hydrocarbon extracts are by far the most popular among longtime smokers. They are extremely easy to produce, but I am not a fan of ingesting any residual solvent or impurities in the solvent. Coming from the oil and gas industry I am very aware of the effects of the ingestion of hydrocarbons, none of which are good.
Hydrocarbon extracts include shatter, wax and budder. Shatter being a transparent brittle concentrate, wax is opaque and crumbles, and budder has a very smooth texture. The techniques to produce all of these products is the same, but due to a variety of variables the product ends as shatter or wax.
And as far as I can tell budder is one of the previous ones that has been warmed and whipped to incorporate a bit of air into the final product.
The advantage of hydrocarbons over ethanol is that they are more selective in their solubilities so they tend to have less green color since chlorophyll is not soluble in hydrocarbons. Another advantage to this techniques is that because propane and butane are gaseous at ambient pressure and temperature the evaporation process is shorter and can be done at cooler temperatures than ethanol, thus preserving more terpenoids and flavonoids.
Lastly I come to carbon dioxide. I still have a hard time calling this a solvent, for most of my life as a chemist, CO2 has been an fairly unreactive gas or dry ice. In the O&G industry we were exploring supercritical CO2 as an enhance recovery cosolvent. I've had a couple of people ask me why CO2? Basically, it is the least dangerous chemical compound that can reach its supercritical state within economical feasibility. There are some other interesting properties of CO2 that have made it even more attractive as the best extraction solvent.
Namely that its solvent properties vary through its supercritical range which means that you can tune the extraction to be as selective or non-selective as you want.
This is my current state in my own lab. Trying to figure out the differences in extraction products on a chemical level. One the testing side of things, I have seen all of these products test between 50-90% cannabinoids.