This article covers the main processes to reclaim oil concentrates in cannabis manufacturing, which can lead to many kilograms of saved material a year.
by Jeff Wu - August 10, 2022
Reclaiming Oil Concentrates from Cannabis Waste
Properly implementing the recapture of “waste” concentrates like resin or distillate on glassware, tools, wipes, and equipment can lead to many saved kilograms of material each year. This guide to recovering and recapturing cannabis waste covers the main processes for reclaiming oil concentrates in cannabis manufacturing — keep in mind that additional methods and solvents are available beyond the proposed solvents, and some processes require a Class 1 Division 1 (C1D1) environment to function, and state laws restrict the use of some solvents.
Cannabis Waste Falls Into Three Categories:
- 1. “Dirty” refers to material mixed with hydrocarbon solvents like ethanol or isopropanol or a caustic cleaning agent like industrial purple.
- 2. “Clean” indicates that the material can be reused — examples include fresh jar scrapings, tool coatings, and machine-purged material.
- 3. “Clean but oxidized material” applies to old material that can be reused but has developed off-putting flavors — examples include filter paper from a rosin press, activated/denatured live resin from overheating, oil exposed to activated media, and machine-purged material left in open containers for months.
How to collect: Spray and wash down dirty waste materials with food-grade ethanol in a pan and collect the mixture in 5-gallon carboy liquid containers.
Separation and pH correction: The dirty waste mixture is typically washed with heptane and water and vigorously stirred in a reactor at 40 °C. Perform an initial pH test and then retest the solution after multiple water and saline washes.
What to avoid: Avoid soaking recycled paper towels — recycled paper towels are usually made from cardboard and contain heavy metals that can leach into your solution. If the material has only come into contact with washed, clean glassware, then the “waste” material can be distilled to repurify it. Otherwise, the dirty waste must be processed through chromatography to remove heavy metals.
Catalysts to watch for: Caustic agents like industrial purple are basic, which will cause D9 to isomerize to D8 and D10 during distillation. If recollecting agents from the sonicator neutralizes the basic material with an acid, then wash to remove the ions.
End product: Purified distillate that can be reinfused with terpenes or used in products.
How to collect: Spray and wash down clean waste materials with propylene glycol (PG) and collect mixture in 5-gallon carboy liquid containers.
Separation: When water is added, propylene glycol (PG) immediately crashes out of the mixture to form a milky aqueous material. Vigorous stirring in a 40 °C reactor is required to remove small pockets of PG after multiple water washes.
What to avoid: Avoid regular solvents like ethanol and propanol — these are difficult to purge out without removing live resin terpenes.
Catalysts to watch for: Oxygen and time — it is essential to collect and process fresh material within about six weeks — oxidation impacts taste and color.
End product: A mixture/blend of live resin or rosin from all batches that can be partly re-flavored with additional terpenes.
How to collect: Spray and wash down clean but oxidized waste materials with propylene glycol and collect the mixture in 5-gallon carboy liquid containers.
