Closed-Loop Hydrocarbon (BHO/PHO)

Hydrocarbon extraction uses light, non-polar solvents, most often butane (BHO), propane (PHO) or blends of the two, to dissolve cannabinoids and terpenes out of plant material. In a closed-loop system the solvent never vents to atmosphere: it is stored in a tank, chilled, passed through packed material columns, collected with the dissolved oil, then recovered and returned to the tank to be reused.

How a closed-loop run works (overview)

• Material columns: biomass or fresh-frozen material is packed into stainless columns. Sizes like 6x48 and 8x48 mean the column's diameter and length in inches, which sets how much material a single run can take.
• Cold solvent wash: chilled solvent passes through the material. Low temperatures favor terpenes and cannabinoids and keep waxes, chlorophyll and water-soluble compounds in the plant.
• Collection & recovery: the solvent and oil mixture collects in a vessel, and the solvent is recovered off the oil, either passively (temperature and pressure differentials) or actively (a recovery pump), and condensed back into the tank.
• In-line filtration: many systems add dewaxing columns or filter media (for example, the CRC filtration I have posted about) to refine color and clarity.

Product types

• Live resin: made from fresh-frozen material to keep the living plant's terpene profile.
• Sauce / HTFSE + diamonds: the extract separates into a terpene-rich liquid and THCa crystals (see Diamonds and Terpene Separation).
• Badder / budder: extract whipped or agitated while purging so it nucleates into a soft, frosting-like texture.
• Shatter: a stable, glass-like sheet, purged without agitation so it stays clear.
• Wax & crumble: opaque, nucleated textures, from soft wax to dry, crumbly consistencies, depending on moisture, heat and how it is purged.

Texture depends mostly on the starting material, the terpene content and how the extract is handled after recovery (agitation, temperature, time). The same run can be steered toward several different products.

← All extraction methods