What Causes Green Hash? (chlorophyll contamination explained)

The worst thing you can see in your collection bag is green hash. There are in fact a number of factors that can cause your bubble hash to come out green, but the root cause is always chlorophyll laden plant matter in the bubble hash. Green hash is much more common when using fresh frozen material, but I have seen it with dried starting material as well. In this article we explore the most common causes of green hash and how to prevent it.

green hash on freeze dryer tray

Improper Agitation Causing Green Hash

Perhaps the most common cause of green hash is using overly aggressive agitation techniques. Unfortunately many manufacturers of hash extraction machines use bottom-driven impellers. These operate at a high RPM and shear plant matter into small pieces that then end up in your 45-159u fraction of bubble hash.

bottom driven agitation causing green hash

This is why all Hashtek Ice Water Agitators use top down, low speed & high torque agitation. This prevents the agitator from causing shearing of plant matter into small pieces that end up in your hash.

top down bubble hash agitation

Freezer Burned Material

Another common cause of green hash is freezer burned cannabis. I often like to use open containers or trays to quickly freeze the material and prevent condensation within the bag. At scale we use walk in freezer and sheet pan carts.

The tradeoff is that the material must be run within 24-48 hours, or transferred into thick 6mm poly freezer bags with the excess air removed to prevent freezer burn. Low level of vacuum should be applied to the bags whenever possible.

Fresh frozen material should be processed as soon as possible, ideally within 1-2 weeks of harvest. In my opinion the best form to store cannabis in is bubble hash. If you are pressing hash rosin the material can be pressed as needed, while for traditional hash or frenchy tek it should be processed and then aged at cellar temperature for 6-12 months.

freezer burned cannabis which can result in green hash

When cannabis is freezer burned it causes rupturing of cell walls and major degradation of the material. The resulting hash will have a ‘green taste’ and the terpene profile of freshly cut grass (not good!)

Water Temperature Too Warm During Agitation

Bubble hash agitation requires frigid cold water (0-2 C or 32-36F). The primary reason for this is to keep the waxy trichome heads from melting and releasing the terpenes and cannabinoids they encapsulate. I have noticed that if the water is allowed to get too warm you are much more likely to pull green hash. I have two hypothesis for why this happens. I think that if you release too many terpenes into the water by melting/shearing trichome heads the terpenes begin to act as a solvent that pulls non-polar chlorophyll from the cell walls of the plant matter. Another possibility is that chlorophyll’s water soluble sister molecule chlorophyllin becomes more soluble in water as temperature increases.

jacketed agitation tank

In my experience allowing your input material or agitation water to get too warm without a doubt contributes to green hash. Keeping everything cold is critically important. This is why our Hashtek Agitators always come with heavy duty Pelle Polare neoprene jackets that insulate the tanks and help preserve cold temperatures.

Remediation of Green Hash

Sometimes the color can be improved by aggressively rinsing the hash with RO water during the bubble hash collection stage. In my opinion green hash is not worth using in edibles without further remediation.

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