When it comes to weed, winterization is a refinement process used to remove fats, lipids, and other unwanted compounds from oil that has been extracted from the cannabis plant. Winterization, also known as de-waxing, purifies crude extracts by chilling the solution so that fats and lipids solidify and can be removed, increasing the quality and flavor of the resultant oil. Winterized concentrates are available in a variety of consistencies such as shatter, batter, crumble, and wax.

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Winterization process

Cannabis winterization is achieved by mixing cannabis extract with ethanol and chilling the solution to well below freezing so the undesirable compounds solidify. The solution must be held at the sub-freezing temperature for at least 24 hours before it's forced through a series of filters with decreasing micron sizes to remove the solidified wax, lipids, and fats from the oil. The final step involves removing the ethanol from the solution. 

Extraction methods and winterization

Winterization comes into play to varying degrees depending on the extraction method.

  • CO2 extraction: CO2 has become a popular solvent for cannabis extraction in the last few years. While it doesn't rely on harmful chemicals such as butane to separate cannabinoids from plant matter, it does pull the highest amount of lipids from the plant material. This makes winterization most important in commercial extraction operations that use CO2.
  • Butane extraction: Butane extraction results in a moderate amount of lipid material in the oil. BHO and the concentrates made from it are often cloudy as a result. 
  • Ethanol extraction: Chilled ethanol pulls the least amount of lipids from cannabis. Using ethanol for extraction means fewer impurities in the oil and less need for winterization. 


How do you winterize hemp?

Any cannabis extract is winterized in the same manner, regardless of whether it was extracted from hemp or marijuana.

Should you winterize rosin?

Rosin isn't usually winterized, but screens or rosin bags can be used to filter out plant material. 

Why does winterization matter?

By removing lipids and other unwanted material from extracted oil, winterization makes room for higher cannabinoid content. Lipids also cause oil to cloud up, and they burn and taste bad when vaped. Cloudy oil that tastes burned when vaporized and has fewer cannabinoids is considered lower quality by consumers. 

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The information contained in this site is provided for informational purposes only, and should not be construed as medical or legal advice. This page was last updated on August 5, 2022.