This is the third part of a nine-part series detailing the cannabis extraction market and processes used to extract desirable compounds from the cannabis plant.
In this part of the series, we start by discussing the oldest forms of cannabis extraction techniques and how some of the same principles are used in modern-day extraction machines. We will then discuss some of the more recent rudimentary extraction techniques and possible drawbacks to those solutions.
To navigate to other parts of this cannabis extraction series, follow the links below:
Part 1: Cannabis Extracts Market
Part 2: Overview of the Cannabis Plant
The Evolution of Cannabis Extraction
Historically, cannabis extraction has been focused on the production of hashish, a substance made from sticky trichomes on the surface of the cannabis plant. Evidence has been found suggesting ancient peoples in the Indian subcontinent have been making crude forms of hashish for about as long as they’ve been cultivating it, (~6000 years). These early forms of extraction were most likely performed using hand rubbing techniques to form balls of hash. As knowledge and technology improved through the centuries, new forms of cannabis extraction have been invented and refined until reaching the relatively efficient processes we use today.
In this part of the Cannabis Extraction series, we will take a closer look at the historical extraction techniques used for cannabis, and what benefits and detriments each process provides.
Hand-Rubbing Charas
As mentioned above, hand-rubbing cannabis to produce crude hashish balls has existed for thousands of years. Most notably, these techniques have been used in the northern parts of India and neighboring countries to produce charas, the first form of cannabis concentrate. Charas is made by hand-rubbing the leaves of live female cannabis plants, slowly collecting the resin on the palms of a persons hand. Over the course of many hours, this resin continues to collect on the hand until the person begins to form the substance into a ball.
The difference between charas and hash is that charas is made using the resin from a live cannabis plant, whereas hashish is made from the resin of dead cannabis plants. Although exact rates of production are difficult to quantify, it’s believed that a skilled hashish “rubber” can produce between 10 – 50 grams of hash per day, depending on the quality needed.
While this traditional extraction technique has begun to slowly disappear with the use of modern commercial machines, it is still practiced by some people in India, Nepal, and Pakistan.
Sieve Rubbing Hashish
Sieve rubbing hashish has been used in a variety of forms for the past 900 – 1000 years in Middle Eastern and Asian cultures. The technique is simple and involves rubbing the cannabis leaves on or above a fine-mesh sieve or similar textile to remove the resin glands. Ideally, the resin glands pass through the fine-mesh sieve and can be collected from below. The quality of hash produced can depend on how fine the sieve used is, and how many times the cannabis material is processed through the sieve.
There are countless varieties of sieves made by different cultures throughout the centuries, but all with the same general technique. Some cultures used large woven carpets to rub the leaves on and collect resin at the bottom of each knotted area. Once finished, the carpet would be turned over to shake the resin loose.
While some of these rudimentary techniques may still be used today, innovation over the centuries has led to the creation of more refined processes, albeit still using some of the same principles.
Ice Water Extraction (Bubble Hash)
A relatively recent extraction technique, bubble hash first became popular in the mid-late 20th century. The original and simplest way to produce bubble hash involves using dried cannabis flower, cold water, a vessel, paddle, and mesh filter. The paddle is used to agitate the cannabis flower submerged in the cold water. As the leaves are knocked around, trichome glands fall off the leaves and filter through the mesh filter or screens.
Depending on the micron size of the screens used, further refinement is usually needed. Once the product has been refined, it is either freeze-dried or air dried before packaging.
Since its invention, this technique has been further refined and scaled to various sizes. Bubble hash machines are available from numerous manufacturers for small and medium-sized producers.
Dry Ice Extraction
Dry ice extraction is another technique commonly used in homes or small scale settings. It involves using dry ice, a bucket, hash bags, and cannabis flower. The flower and ice are placed in the bucket which is then shaken for 3 – 4 minutes to agitate the trichomes. The dry ice instantly freezes the trichomes and makes it easier for them to fall off during the shaking. You then turn the bucket over, pouring everything into a hash bag. The hash bag has small mesh filters on one side to allow the loose trichomes to fall through and be collected on a flat surface.
Different micron size bags are available, and in some cases, producers will sift the resin through several decreasing sizes to improve the purity of their hash.
New Cannabis Extraction Techniques
Throughout the centuries, cannabis extraction processes have continued to evolve from predominantly physical processes to more efficient chemical ones. This can be seen in the transition from hand rubbing, sieving and ice water techniques, towards modern day solvent extractions.
When the value of cannabis extracts was realized, investment flowed into the cannabis industry. As a result, ancillary industry participants (equipment manufacturers) began to repurpose solvent extraction equipment for use in the cannabis space. CO2, ethanol and hydrocarbon extraction have all been repurposed from other industries.
As more countries begin to legalize cannabis, the rapid pace of innovation in the industry will continue to provide safer and more efficient processes. While commercial extraction processes become exclusively solvent based, physical transformation processes will continue to provide DIY hobby growers in the LEGAL market an opportunity to produce their own extracts.
Check out Part 4 of this series to learn more about one of the main solvent-based extraction systems used by commercial producers: CO2.
