Is rosin an extract or a separation?

It seems easy; Oxford defines extraction as “the act or process of removing or obtaining something from something else”. And rosin is a cannabis concentrate made using heat and pressure. But rosin falls under the category of extracts, while hash is a split for reasons not found in the lay dictionary.

A chemistry textbook defines extraction as a phase change instead. And THC acid, the form of THC made by the plant, switches phases when it dissolves in a liquid solvent. For example, the water dissolves some chlorophyll. But trichomes, still the plant matter, fuse with the water during hash making.

The technical definition of extraction, which is “tantamount to the general phenomenon” in the process of partitioning, is “the division of a solute between two phases”.

Hashish is a separation

Abrasion knocks off glandular heads containing the rich body of terps from the cannabis flower. Hash is a collection of these heads known as trichomes. And water is a solvent used in hash making. However, no solvents are required to make hash. Water instead aids separation rather than a solvent. So hash is a mechanical separation and not an extract in the strict chemical nomenclature.

A solute is “the smaller component of a solution that is assumed to be present dissolved by the solvent.”

Switch phases with rosin

If we define rosin as an extract (distribution), we need to demonstrate that a phase change has taken place. THC-a must also dissolve during the extraction process. Otherwise, rosin is a mechanical separation in the same category as bubble hash or kief.

Dissolution involves “the mixing of two phases to form a new homogeneous phase (i.e. the solution)”. A phase is the “unit of a system of matter that is uniform in chemical composition and physical state”.

Heat can melt substances in cannabis and its extract. Given the temperatures used to make rosin, presses are likely to dissolve some solids. Additionally, melting THCa with heat alone will likely cause more decarboxylation. This implies that something else is causing a phase change while pressing.

Cannabis contains solvents in the form of terpenes. If hot botanical solvents don’t dissolve THC-a, how does the cannabinoid squeeze through a micron-sized filter? This suggests that rosin presses are beating the THC acid out of the waxy protection of their trichomes. If rosin is a mechanical separation, then it has to be powdered THCa. But if hot terpenes contain liquid-solid cannabinoids, then rosin appropriately belongs in the extract category.

Let us know how you define rosin in the comments. And do you think hash is a separation or extraction?