Step 3 - Winterize

Step 4 - Winterize


Winterization is a step to remove plant waxes from the crude oil. The petroleum industry has been dealing with this since the early days of gushers. The cooking oil industry as recently as the 1950s. The implementation in the cannabis industry was popularized by Gray Wolf with his published QWET and QWISO procedures. The theory being plant waxes crystallize at cold temperatures into a visible mass that can then be removed through gravity, vacuum or centrifugal force filtering. The cooking oil industry performs winterization as one of the refinement steps, but interesting enough, this is done later in the refinement pipeline rather than as a first step.

For cannabis products, winterization is normally done with extraction by using sub-zero alcohol. Historically, this has taken 24-48 hours to freeze the plant and large volume of alcohol, wash the plant then filter it. Again, all this cooling takes quite a bit of time with the volume of alcohol. Typical extractions use quarts, up to gallons of alcohol which must be kept near frozen through out the entire extraction process.

Then in the summer of 2021, through a simple test, it was found the waxes are in fact very hardy, surviving a hot distillation. This means winterization can be performed later on which led to the discovering of Rapid Winterization.

An Interesting Discovery

After distillation in water, the concentrated oils were redissolved in warm Ethanol and something happened. Wax crystals started forming immediately as the warm ethanol cooled. Through further testing, it was found that most of the waxes crystalized under an hour. Performing the water distillation removes compounds allowing for waxes to isolate at higher temperatures.

The picture on the right shows a bowl of liquefied oil waxing up just by sitting in ice water. Click on the picture and open in a new tab to view full size.

In the past, winterization has been performed on large volumes of alcohol. What happens when its just a quarter cup of Ethanol? Freeze time scales in a favorable direction. This small amount of alcohol needs very little time to reach -20c/-0f, the coldest temp in your freezer. If you have some dry ice, you can speed up the freeze even more by creating an alcohol/dry ice bath and set the bowl in that. The dry ice bath can easy fall below -40c/-40f so be careful and always wear protective gear. Boiling action of the bath starts fast, but slows as the alcohol reaches it's coldest temperature. 

There is another benefit of having winterization follow Distillation. By first distilling in water, virtually all the polar and most semi-polar compounds are removed from the oil, leaving a majority of non-polar lipids, IE, fats, waxes and oils as a dark resin. Warmed 95% Ethanol is used to melt this sticky resin. Lower proof Ethanol can be used, but has higher water content making it harder to dissolve the resin. This is useful for patients without access to 95% alcohol. More on this later in Tips and Tools.

Again, here is the power of polarity. Water is the most polar solvent on the planet, the polar opposite of the non-polar cannabis resin. By mixing the two, you may see the resins actually pooling and flowing like wine veins on the sides of a wine goblet before solidifying into waxes. This is polar forces at work causing separation between the dissolved oils and water as the solution cools. Freezing this amount of fluid takes very little time. Waxes crystallize faster in this small volume of alcohol. 

Once the waxes have solidified, pour this through a cone coffee filter or multiple layer paper napkin filter. This allows the dissolved oils to flow through, but catches the waxes. A paper coffee filter is thicker with the tradeoff that it takes more time to pass the solution. The paper napkin is a bit thinner and provides very adequate fast flow filtering. All this can be performed in just a few minutes with the reduced volume of alcohol in the freezer.  

The pictures on the right shows collected waxes. The picture on the far right looks bleached. This is done by adding an addition ounce of ethanol to the picture on the left and stirring. Be careful as the napkin is thin.

After the waxes have been collected in the paper napkin, save the napkin to harvest the waxes for other uses. Your dissolved oils are now ready for final reduction.



From the prior step, you should have a small bowl of dissolved oils in alcohol and a small jar with about an ounce of alcohol.


For further reading on waxes, please visit Gray Wolf’s post on Plant Waxes.

For further reading on winterization, please visit Gray Wolf’s post on Winterization.

For further reading on ethanol winterization, please visit Gray Wolf's post on QWET.

For further reading on isopropyl winterization, please visit Gray Wolf's post on QWISO.

Fun Discussion:

Here's Fun Science: A history question to ChatGPT on when dewaxing became a thing -

Q: About what year did the cooking oil industry implement dewaxing as part of the cooking oil refinement process? 

A: The implementation of dewaxing as part of the cooking oil refinement process in the cooking oil industry began in the mid-20th century. The exact year can vary depending on the specific region and company, as different companies may have adopted the process at different times. However, dewaxing as a refining step to remove waxes from cooking oil started gaining prominence in the 1950s and 1960s.

Dewaxing is a process that involves chilling the oil to low temperatures, allowing waxes to solidify and separate from the oil. This step is particularly important for oils that tend to solidify or cloud at lower temperatures, such as some vegetable oils like sunflower oil or corn oil. By removing waxes, the oil's clarity, stability, and functionality are improved, making it more suitable for various cooking and food preparation applications.

Since its introduction, dewaxing has become a standard practice in the cooking oil industry to enhance the quality and usability of vegetable oils, ensuring they remain liquid and clear even at lower temperatures.

Tips and Tools

Tip: The longer the freeze time, the greater the yield losses. This is because fats, oils, and waxes are lipids which are non-polar. More time together means more bonding. Take a look at the color of the waxes above from a Rapid Winterization. The left picture is darker showing chlorophyll that bonded over time. This bonding goes for cannabinoids as well, so keep the winterization down to an hour.

Tip: If you have access to Dry Ice, you can accelerate this freezing process. Be careful! Always wear protective gear when using dry ice. Place your Dry Ice in a larger metal pot and add at least 91% Isopropyl. After a couple minutes, the boiling will slow as the alcohol reaches it's coldest temperature. Now, float your bowl of dissolved oils in the second bowl. The dissolved oils will quickly reach a low of -40c/-40f.  

Tip: Save the waxes in a closed container in the freezer for later use to make topicals, etc.


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WARNING: Never distill alcohol near open flame.  Alcohol vapors are highly flammable so always distill in well ventilated spaces.

This oil is appropriate for oral ingesting and vaping.  Due to the potential of residual salts, do not torch this oil.  Torch temperatures can reach over 760c/1400f and can vaporize any residual salts. 

Disclaimer:  Your use of any information or materials on the C.H.S. Website is entirely at your own risk, for which we shall not be held liable. It shall be your own responsibility to ensure safe use and operation of any processes, products, services or information made available through C.H.S publications and Website.

Revision History - RxCE Winterize Step

23/10/01 Page published.

23/09/20 Page done

23/06/10 Soft release candidate published to the FB group.