Why winterization stabilizes hash oil extracts

Why winterize your extract? Stability.

Winterization removes impurities – specifically plant lipids and waxes. This is a very important step if you’re trying to make shatter because the lipids will soften up the extract, giving it a pull-and-snap consistency and increase the tendency to auto butter.

Who needs to winterize?

People go through great lengths on their butane extraction system to have in-line dewaxing (winterization). Even with in-line dewaxing, you will not get a fully dewaxed product. Not all extractors have this built in capability so the alternative is to winterize with ethanol – this is particularly true with CO2 extraction rigs, where high temperatures and pressures prevail. If you want to remove plant waxes, you either have to winterize in-line or do winterization after extraction.

Four steps to winterize.

The process is simple to do. Specialized equipment stops with a freezer and a simple laboratory funnel/filtration system. The process roughly looks like this: fully dissolve the extract in warm ethanol by stirring; freeze the extract for 36-48 hours; filter the extract; purge the extract of ethanol. Sounds simple right? This guide will try to help you along the way.

Step 1: dissolve your extract in a 10mL:1g (ethanol:extract) ratio.

First, it’s not blasphemous to use warm ethanol. My first job as chemist was rife with lessons in solubility. As you’ll see on the Wiki article, temperature is one of the few variables that can be easily controlled and used to make your life easier. The lowest terpene boiling point is Beta-Caryophyllene at 119C; that said, you’re well below that temperature to get your extract to dissolve. Anything over 30C and below 60C will serve your needs, but the lower the temperature to dissolve, the better.

Once your ethanol is warmed it can be used to dissolve your extract. Choosing the amount of ethanol used is up to you, but keep it simple with a 10mL to 1g ratio by weight of ethanol to extract. Simply put, for every 1g of extract, add 10mL of warm ethanol. Once you’ve added the ethanol, you can stir manually with a small lab spatula or put it on a stir plate with a stir bar until the extract is fully dissolved.

Step 2: freeze your extract/ethanol solution.

Now that you’ve suspended your extract in ethanol, it’s time to freeze it. The goal here is to make a solution that’s similar to an oil/vinegar salad dressing – we want the plant waxes to float on top. Think of the ethanol as the vinegar and the plant lipids/waxes as the oil. Now what may not seem intuitive is that the plant lipids/waxes dissolved into the warm ethanol. Remember how I said temperature was a key to solubility? It still is – now we’re just taking advantage of the fact that lipids/waxes have a much lower solubility in cold ethanol compared to warm ethanol.

To be very sure that all the plant lipids/waxes have precipitated out of the solution, you just need patience, or very cold temperatures. If you have dry ice on hand, you can precipitate the lipids/waxes in 1-2 hours. If you only have a standard freezer, you’ll need 36-48 hours to fully precipitate the lipids/waxes. You will know your extract is ready for the next step when you have a layer of lipids/waxes formed on top of the ethanol solution.

Step 3: filter the plant lipids/waxes.

The laboratory solution is to have a vacuum pump, Buchner funnel, and filter paper. That is my preferred method. If you’re low on funds, the standard method is to use a coffee filter and funnel, letting gravity do the work. Either way, an important step is to have your entire filtration setup at the same temperature as the extract/ethanol solution; that way you will prevent the lipids/waxes from going back into solution from coming into contact with a warm funnel and filter. Place your filtration set up in a zip-lock bag and in the freezer an hour before beginning to work. The zip lock bag helps prevent buildup of condensation while you’re getting ready to filter.

Once you have your filtration apparatus set up, wet your filter paper with cold ethanol and apply a slight vacuum. On top of you filter paper, place 1-2 coffee filters into the funnel so you can easily remove the waxes. Now you can SLOWLY start to pour your extract/ethanol solution onto the filter paper. You don’t want to pour the whole batch in at once because your coffee filter will get saturated in plant lipids/waxes. The wax buildup prevents your cold ethanol/extract solution to flow through the filter, and you’ll end up redissolving more waxes.

At the end of step 3, you will have a waxy substance that looks like cannabutter sitting on top of the coffee filter and a büchner funnel filled with a translucent amber oil of the highest purity. You’re almost home free to having a highly stable wax.

Step 4: purging off ethanol.

When we talk about purging, we’re talking about evaporation of solvents. Those solvents could be butane, and/or ethanol. Purging is an easy job when you have a vacuum and vacuum oven on hand. Ethanol boils off at 78.5C at atmospheric pressure. If you pull a full vacuum (assuming you can pull -28.5”Hg), it reduces ethanol’s boiling point to 12.8C, which is well below room temperature.

The question to ask next is, do you want to reclaim your alcohol, or do you want to evaporate it off? If you desire to reclaim, the process requires a distillation apparatus, which is out of the scope in this article. If you’re evaporating off the ethanol, the standard practice is to transfer the dewaxed extract into a pyrex baking dish over a water bath; cover the pyrex dish with cheesecloth so that dust particles aren’t falling into the extract.

Evaporate off the ethanol until the extract is still workable with a spatula, and is a consistency/viscosity that is between molasses and honey. Check out the post on how to handle an extract after winterization. That describes the process after winterization and the initial purge.


You’ve followed the four steps of winterization. You’ve removed plant lipids/waxes and now have an enriched/purified cannabinoid solution. The biggest benefit to this process is that you now have an extract that will more easily “crystallize,” or become a stable product. The fewer impurities left in the final product, the longer the extract can be stored without changing its appearance and texture. Whether you choose to perform in-line dewaxing or to perform dewaxing with ethanol as described here, you’re well on your way to making high quality extracts if you do either.


As always, if you have any questions please post them in the comments section. Your questions and time are valuable and we will make every attempt to help you through your process.