Definition - What does Residual Solvent mean?
In cannabis processing, residual solvent, as the name suggests, is the remaining solvent that is present in cannabis extracts. Residual solvents usually occur when the required processing and solvent-purging methods or steps are not properly utilized.
Some products that may have residual solvents, impurities, or toxic odorants are BHO, Rick Simpson Oil (RSO), Budder, Honeycombs, Crumbles, Waxes, Honey Oils, Shatter, Amber Glass, and Hash.
Hydrolife explains Residual Solvent
A solvent is a liquid that is used to dissolve a substance in order to form a solution. In terms of marijuana extraction, a solvent is used to separate the psychoactive compound THC from the cannabis flower.
There are a variety of processing methods that are used when manufacturing extracted cannabis products. Solvents such as butane are used to obtain concentrates like hash oil, dabs, wax, and shatter, which carry a heavier dosage of THC while leaving the unneeded plant matter behind.
During the extraction process, solvents are used to extract the desirable compounds from cannabis plants. There is then a process of removing these solvents from the end product. However, the processes aren't perfect.
Residual solvents can sometimes be present (get left behind) in cannabis oils, shatters, waxes, and budders. They occur after the extraction or after post extraction processes such as winterization, which consists of soaking the marijuana extract in alcohol and freezing it in order to separate the residual products.
When the solvents that were used are not completely removed, there is a possibility that the residual solvents can remain in the cannabis products that are smoked or inhaled by users in appreciable quantities. Depending on the solvent in question, this may or may not be harmful to the user.
Although there is a risk in there being residual solvents in medicinal marijuana concentrates, there are benefits to using concentrates over using traditional cannabis. Concentrates contain higher concentrations of cannabinoids, so a smaller amount of the product is used for the amount of THC/CBD consumed and so less toxins are inhaled by users. These potent extracts can also be used to make edibles with high levels of cannabinoids for oral consumption. In some extracts, terpenes are so highly concentrated that it gives the consumers the full entourage effect and a noitceably superior taste.