Winterization SOP, my take on it anyways.

Most likely you will come to the same conclusion I did, you must winterize. The exception would be if you purposely want waxes in your extracts. Let's describe the process in further detail.

Winterization is the process of using differences in melting points to separate a solution into its parts, therefore fractionation. The gist of it is that fats, lipids, and waxes of botanical extracts precipitate at different temperatures. We exploit this fact to filter out fats that may be liquids at room temperature, but solids when cold.

Though I could write pages about this topic, this is just my take on how we do things and not the science behind why we do it this way. You can read more about crystallography here.

Anyways, step one involves heating the oil to fully melt all the lipids, fats, and waxes so their crystal structures fully reset. I believe this is the most important part of this process. I recommend heating oils to 60 Celsius because it achieves a full melt, and also is below the boiling temperature of ethanol, our solvent of choice.

Step two involves dissolving our oil in a warm solvent at a 10:1 ratio. So that would be 1 gallon of oil for every 10 gallons of solvent. I like ethanol for many reasons and 180 proof (90%) at that. Using 99+ percent ethanol works but is more expensive and ethanol tends to attract water (azeotrope). No matter what you do your ethanol slowly drops in purity. Fortunately, water helps us in the fractionation process since it makes the fats less soluble in our solution.

Step three. We let the solution reach room temperature (25C) and sit for 1-2 hours. Most of the heavier fats drop out of suspension at this stage and can be filtered out using filter paper in the range of 45-25 microns. This first filtration pass is called roughing and works extremely well for CO2 and BHO based extracts.

Step four, we add perlite to our solution, and we chill the solution to 0C and allow fats to drop out of suspension for 1-4 hours. Perlite gives fat crystals a place to grow and make subsequent filtration much easier. At this point we filter using 10-micron paper, preferably using a filter aide such as DE to prevent the paper from clogging.

The final stage requires winterizing a third time at a temperature of -65C to -86C for up to 24 hours. Let the solution warm closer to 0C after winterizing to make filtration faster. Don’t worry, fats will not dissolve at these temperatures. Filter using 1-3 micron paper, usually filter aide is not necessary. Now you are ready for solvent recovery.

The whole process works better the slower you reduce temperatures, the fat crystals form larger and are easier to filter out and more fats drop out of suspension. Typically, fats do not coagulate fully when winterizing, even if you freeze your fats to -86C from the start. This is explained in another blog post but what is important to understand is that the slower the rate of cooling the better. Also, you will repeat this process up to 4 times if you want to remove all fats. Degumming before removing fats also helps achieve a more complete winterization. Never carbon scrub before winterization because the carbon gets clogged with fats.