To begin with, you need a variety of cannabis that is high in Cannabidiol (CBD). Some established manufacturers have developed their own varieties of cannabis to get a higher yield from their production methods. Each manufacture chooses the methods they use based upon their needs.
You will find our article titled What is Cannabidiol (CBD)? very helpful with understanding CBD.
This is probably the most common method used for a high concentration oil, mainly because it is simpler and less expensive.
It involves running a solvent through the plant material, such as flowers, leaves etc., to dissolve the cannabinoids and flavours into the liquid. The liquid is then evaporated away to leave the concentrated cannabinoids and flavours in an oil.
There are a couple of downsides with this process. One is that the solvents used may leave trace residues in the final product, though good practices will minimize this. Another concern is that the solvents also remove chlorophyll and this makes the liquid more bitter and greener.
Carbon Dioxide (CO2) Extraction
This method uses Carbon Dioxide (CO2) at extremely low temperatures and very high pressure. This isolates and preserves the purity of the extracted oil. By not using toxic solvents like butane and hexane the risk of toxic dangerous residues is minimised.
This method requires expensive machinery, such as a closed loop extractor. The process is complex, but it does produce a highly concentrated safe product.
Typically, the process involves three chambers. The first chamber contains solid pressurised CO2 (dry ice), the second chamber the plant material and the third chamber extracts the finished product.
CO2 is pumped into the second chamber with the plant material. It is then set to a specific pressure and high temperature. The supercritical CO2 then runs through the plant material and extracts the CBD. The CO2 and CBD mixture is pumped to the third chamber where it is set to a lower pressure but higher temperature. The CO2 separates by rising to the top of the chamber. The oils drops to the bottom of the chamber for collection.
A benefit of this process is that it can be used to separate CBD from material that also contains Tetrahydrocannabinol (THC).
You can discover much more about THC in our article: What is Tetrahydrocannabinol (THC)?
A safe and inexpensive method is to use an oil, like olive oil, to produce cannabis infused oil. This is a very old method that dates back into antiquity and requires the simplest of equipment.
The first step in this process is to decarboxylate the plant material and activate the chemicals in the material. That requires it to be heated to a specific temperature for specific time.
After that the material is added to the oil and heated to 100ºC for a period of 1 to 2 hours to extract the cannabinoids.
The resulting product is an oil infused with cannabinoids. Unlike highly concentrated oils, this oil contains a lot of the original base oil, such as olive oil, and thus users must consume a lot more product. As the product is perishable, it must be stored correctly, in a cold dark environment, to maintain the quality.