About winterization
Winterization is a method to remove any waxes fats and lipids from extracts, this is increases the quality of the extract and also makes it suitable for using in tinctures and eliquids.
When winterizing ethanol is used as a solvent (polar protic) for the extract you are using. When cooled in a freezer the waxes fats and lipids in the mixture clump together and drop to the bottom of the container they are in. After being in the freezer 24hrs the mixture is then vacuum filtered with a coffee filter (25-30um).
The mixture is then placed in the freezer for a further 48hrs and then filtered with a smaller 5-8um filter and once again placed in the freezer for a further 72hrs. The last stage of filtration a smaller 0.7um filter is used.
The resulting extract usually has a much more golden appearance to it.
It is not recommended using isopropyl alcohol as a solvent in the extraction stage because it pulls more waxes and and fats out of the original plant material. If your extract has been extracted using isopropyl alcohol you will see that a large amount of yellow wax and fats on the filters especially on the first filtration stage of the winterization process.
Equipment Needed
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Digital magnetic stirring hotplate |
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Freezer |
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Magnetic stir bars |
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30cm Retort stand |
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Glass beakers |
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Glass stopper |  |
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Clips |
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Keck clips |  |
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Buchner Funnel |
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Conical flask 24/40 |  |
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Cold Finger |
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Pipe |
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Vacuum Pump |
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Materials
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Ethanol |
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Glass wool |
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25u Filters |
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5-8u Filters |
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0.7u Filters | |
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Labels |
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Marker pen |  |
Buchner types, pipes and fittings
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Buchner funnel and flask This type of buchner filter setup uses a rubber bung with a hole in that the buchner filter goes inside of. The vacuum pipe connects to the flask. This setup is the cheapest method there can be a tendency for fluid leaving the funnel to be sucked into the pipe into the cold trap. If you are using this equipment you will need a conical flask and rubber bung for when the mixture goes in the freezer, bare this in mind when pricing equipment. |
The buchner funnel below below has a tube that leads directly to the conical flask eliminating any risk of fluid being pulled down the pipe by the vacuum. In addition when used with the glass stopper, it then can be used for storage in the freezer.
The glass buchner funnels we recommend have a glass plate with holes in, and not the sintered plate. The numbers on these items denote the fitting size a 24/40 or 24/29, both have the same taper angle but have differing lengths, a 24/29 can fit into a 24/40. You will need a matching keck clip to make sure the 2 parts are sealed, a small amount of lubrication between the joints prevents them from locking together.
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| Glass Buchner funnel 24/40 | Conical Flask 24/40 | Glass stopper 24/40 |
With both types of buchner funnel its a good idea to get double the size of capacity you are going to filter (250mL mixture use a 500ml flask or buchner flask), this also reduces the risk of fluid entering the cold trap/vacuum pump.
The pipe can be made of most things when winterizing, but you will need acetone resistant pipe when using the funnel in the extraction process (PTFE or NYLON). When you by pipe its usually sold by stating its internal diameter (6-10mm) and outer diameter (>8mm), the difference between these measurement is the thickness of the pipe wall.
The pipe wall needs to be strong enough to withstand the vacuum and not collapse, this will vary on the material the pipe is made of. The pipe also needs to connect to the cold trap too, so allow for this. The pipe from the cold trap needs to connect to the vacuum pump also, so make sure all your fittings match up. If you can get fittings on all your equipment that use a GL14, which is replaceable, you will be able to use all your equipment with each other and all the pipework will fit correctly. See pic below.
Cold Traps
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A cold trap or cold finger is a piece of equipment that goes between the buchner funnel and the vacuum pump. Its purpose is to condense any vapor that is evacuated from the buchner flask, which collects at the bottom. If you are not using a chemical resistant vacuum pump, any vapors may enter the pump, by using the cold trap you are reducing the chance of this happening. To further ensure no vapors enter the pump the cold finger can be placed in a cylinder or ice, dry ice, dry ice/acetone mix. |
Vacuum Pump
When choosing a vacuum pump for the buchner funnel, it does not have to have a very low vacuum. If you choose a vacuum pump with a very low pressure (high vacuum) you may need to get a vacuum regulator to adjust the vacuum to a level that is suitable for the buchner, too high a vacuum will tear the filter.
Most of the vacuum pumps on ebay have a very low pressure (high vacuum) but from experience get hot very quickly, and have oil for lubrication and cooling, which can get contaminated by any vapor that makes it past the cold finger.
The best kind of vacuum pump to use would be a diaphragm vacuum pump. Preferably a chemically resistant diaphragm pump would be the best choice but they are quite expensive.
Method
Setup hotplate with stand holding temperature probe above the conical flask. Set temperature to zero and the stirring speed to zero. Put on on your gloves and protective glasses.
Pour 10 times the volume of the extract of ethanol into a conical flask. Place magnetic stir bar into conical flask containing the mixture and put it onto the hotplate.
Lower the temperature probe into mixture. The temperature probe must be in mixture or your hotplate will go over the set temperature. Make sure the temperature probe will not obstruct the movement of the stir bar. Set temperature slightly higher than 35°C and slowly increase the stirring speed to around 500 rpm. Continue until evenly mixed.
label and place in freezer for 24hrs, at the same time place the buchner funnel into the freezer.
Setup the buchner funnel, cold trap and pump again.
Place a 25um filter into the buchner funnel and wet the filter with some of the mixture to create a seal. Place some glass wool on top of the filter.
Turn on pump and pour mixture into buchner funnel.
Once all the mixture has been filtered turn off the pump and remove buchner funnel and discard the used filter.
Put the glass stopper on conical flask and label the flask
Place buchner funnel and the conical flask in freezer for 48 hours.
Setup the buchner funnel, cold trap and pump again.
Place a 5-8um filter into the buchner funnel and wet the filter with some of the mixture to create a seal.
Turn on pump and pour mixture into buchner funnel.
Once all the mixture has been filtered turn off the pump and remove buchner funnel and discard the used filter.
Put the glass stopper on conical flask and label the flask
Place buchner funnel and the conical flask in freezer for 72 hours.
Setup the buchner funnel, cold trap and pump again.
Place a 0.7um filter in buchner funnel and wet the filter to create a seal
Turn on pump and pour mixture into buchner funnel.
Once all the mixture has been filtered turn off pump, remove buchner funnel and discard the used filter.
Label the flask.
Continue to the evaporation stage