Hydrocarbon Extraction
Why all the fuss about hydrocarbons? Much buzz has been generated regarding solvent choice, and with some internet hysterics inevitable, I'll explain some of the choices...
1)Why use hydrocarbons at all?
As a class of solvents, they are nearly ideal for botanical/cannabis extractions, owing to the fact that they are themselves, oils. Since the target cannabinoids and
terpenes are oil-soluble, non-polar molecules, and since
terpenes are already oils at room temperature, we desire a light, easy-to-purge solvent that "selects" for our desired extraction profile, while eschewing all the undesirables. Propane and butane fit the bill nicely. Ethane boils at too low of a temperature, and pentane and the heavier hydrocarbons are already used in additional refining steps as carrier solvents... Other choices could work, such as chloroform, acetone or ethanol, but these solvents are polar and will also extract undesirable molecules like pigments; chlorophylls, xanthophylls, and carotenes to name a few, thus necessitating distillation and further refinements such as hot scrubbing, degumming, brine washes, etc.
2) So why the bad rap, butane?
A-This oily gas is toxic to mammals and fish, and being so, it is natural to want to avoid ingesting any.
- however butane is very easy to purge out of the final product using gentle heat (~100°F), and full vacuum. Residuals of 0 ppm should be standard, meaning you intake far more butane from lighting a joint one time with a lighter than would be present in a dab.
B- Old school hash-makers "open blasting" resins without vacuum purge capability undoubtedly led to some residual solvent being smoked.
- Pyrex on a double boiler will remove *most* of the solvent, but not all.
C-Butane is flammable and can lead to explosions when used improperly or carelessly.
- not for home use.
D- Butane boils near 31°F and so requires some specialized apparatus and operator training.
- closed loop extraction uses an engineered system, and as such needs to be operated by trained personnel.
BUT, since
terpenes are oils, and we want to capture all the
terpenes in order to preserve the original profile of the plant, some of the finest artisanal concentrates are currently made using a 70/30 blend of propane and n- or iso-butane at extremely low temperatures, despite the inherent risks. Commercial product is required to be tested (in Colorado at least), to ensure removal of the residual solvent.
Bottom line: hydrocarbons are A-OK solvents for botanical extraction on a small scale and are preferred for artisan products like "live sauce" or "diamonds n sauce"
Now I'm not knocking water hash; I'll address rosins in another thread...
Happy dabbing!
