To start with I'll try any method to begin my education into extraction.
Eventually I hope to be able to produce clear oils.
Amber, Green, Pink - I don't care really care what colour they are
(although it was amber, the twice I had oil offered over the last 20 years).
I just don't want it to look unclean or an amateur attempt.
I don't want anyone to suspect it's been homemade in a local kitchen.
You have a couple of options, choosing between a polar or a non polar extraction, and once you've made that decision, there are more choices.
Polar extractions use a solvent with a diaelectric constant of 15 or higher, and do a good job of extracting, but extract water solubles and chlorophyll in addition to the targeted plant terpenes. The non polar plant waxes are only minimally soluble in them, so they leave most of them behind.
To make a pristine extraction using a polar solvent, requires more skill and more elaborate techniques than a non polar solvent, but produces pristine extractions when done well.
I prefer to use -18C/0F 190 proof ethanol for polar extractions, and extract material that is frozen to that temperature, so as to keep the chlorophyll and water solubles tied up in ice. I use a 3 minute soak under those circumstances and use up to three soaks to extract most the resin.
You can also use 99% Isopropyl, but have to be more careful with final purge due to toxicity and I only use a 20/30 second frozen soak, because it is far more aggressive than the ethanol.
Some use Acetone, but we don't because it is known reproductive system toxin for pregnant women.
Non polar extractions use a solvent like the simple Alkanes, which also do a good job of extracting, and absorb very little water or chlorophyll. They on the other hand extract the non polar plant waxes, which the alcohols tend to ignore.
Their ease of removal decreases as the length of their chain and Van der Waal forces increase. Methane, Ethane, Propane, Butane, Pentane, Hexane, and Heptane all do a good job of extraction, but the liquid gases like the first four, have to be pressurized above atmospheric pressure, or super cooled to be in liquid form.
Butane is about the shortest molecule that is suitable without a pressurized system, is a simpler process compared to polar extraction, and is easy to purge without also losing the lighter monoterpenes, but it is highly flammable and requires greater caution and attention to detail to win.
Hexane makes an even more pristine extraction, but is waaay harder to purge, and unless you have a vacuum, you will most likely need to wash it several times with ethanol to get the residual hexane below the 130 ppm sensory detectable limits, where it tastes like gasoline.
Heptane does an even prettier extraction, but even harder to purge and also tastes like gasoline.
All of the above solvents do a good job of extraction, the challenge is to limit extraction of non targeted elements, and to hold on to as many of the lighter monoterpenes purging out the residual solvent.
First priority of course is safety, so stick to the ones that you can do safely at your location, using the resources at hand.
