Propane is a solvent that is used to produce cannabis extracts and concentrates. Many manufacturers will use a mixture of butane and propane and this is referred to as blended solvents. The ratio that is typically preferred for shatter and budder based extractions is 70% butane and 30% propane. This ratio gives the solvent the ability to extract a bigger terpene profile and will give a much brighter color than if 100% butane was used for the process. Some labs will prefer to use up to 100% propane for unique products that have higher terpene extractions.
When conducting a propane-based extraction, it is important to keep in mind the pressure and temperatures that are being used. With butane, the boiling point is at -1 degrees Celcius, and that point allows a greater degree of control in regulating the amount of vapor pressure. But with propane, the boiling point is around -43 degrees Celcius. This means that a much greater vapor pressure and cooling system is required.
Because propane has such a high volatility level, it gives the operator a much easier time to distill the solvent. This means that there is a much quicker recovery time in comparison to butane. Blending solvents together doesn’t typically speed up the recovery time. Recovery in most cases is dependent on the solvent that has the slowest recovery time.
Because propane has such a low boiling point, it makes it very simple to purge in a vacuum oven and takes a very small amount of time to remove from the finished product. Propane has the ability to extract very light compounds from the cannabis material, like the terpenes. Even though propane is good at extracting terpenes, it’s important to keep in mind that if the terpene levels are too high, then it could actually irritate the consumer’s throat.