What You Can Do with Moisture Data : Purpl Scientific

There is a pass/fail regulatory threshold in many states, but the particulars vary a little, so you should do some research about your state's rules for "Cannabis Moisture Content and Water Activity Testing" where you live. In California, for example, the Water Activity can not exceed 0.65 (see California Bureau of Cannabis Control code and other state links below):

§ 5717. Moisture Content and Water Activity Testing. (a) The laboratory shall analyze at minimum 0.5 grams of the representative sample of dried flower to determine the level of water activity and the percentage of moisture content. (1) The dried flower sample, including pre-rolls, shall be deemed to have passed water activity testing if the water activity does not exceed 0.65 Aw. The laboratory shall report the result of the water activity test on the certificate of analysis (COA) and indicate “pass” or “fail” on the COA. (2) The laboratory shall report the result of the moisture content test on the COA as a percentage. (b) The laboratory shall analyze at least 0.5 grams of the representative sample of solid edible cannabis products to determine the level of water activity. A solid edible cannabis product shall be deemed to have passed water activity testing if the water activity does not exceed 0.85 Aw. The laboratory shall report the result of the water activity test on the COA and indicate “pass” or “fail” on the COA. (c) If the sample fails water activity testing, the batch from which the sample was collected fails water activity testing and shall not be released for retail sale. Authority: Section 26013, Business and Professions Code. Reference: Sections 26100, 26104 and 26110, Business and Professions Code.

California: https://bcc.ca.gov/law_regs/cannabis_order_of_adoption.pdf

Oregon's: https://secure.sos.state.or.us/oard/displayDivisionRules.action?selectedDivision=1222

Nevada: https://www.leg.state.nv.us/NAC/NAC-453A.html

Washington: https://apps.leg.wa.gov/wac/default.aspx?cite=314-55-102

Very high water activity can indicate susceptibility to molds and other nasty things.

Image from https://www.metergroup.com/food/events/water-activity-and-cannabis/

Moisture content (percent water by mass) is also related to "smoke-ability." (From memory,) most cannabis is sold in the 10-15% moisture range. Very dry cannabis can taste harsh. Cannabis on the wetter side can burn poorly.

Additionally, and perhaps more importantly, water weight affects the overall weight of any purchase. So high water content also means that you're paying for more water per pound than otherwise.

Since Water Activity are both measures of water, they are related. Any measurement that is properly dried and cured (10 - 15% moisture) will be well below the Water Activity threshold of 0.65. Properly cured and dried cannabis is usually around .4 WA on our instrument.

For growers, a quick check of the moisture and water activity may inform decision about their curing and drying process. While THC and CBD readings are invalid at high moisture levels, any Purpl user can follow the drying process from fresh cut to properly dried.

What You Can Do with Moisture Data Print

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