When making a CBD product, there are numerous ways to distill cannabis into your desired end product. Whether you’re looking to achieve a pure CBD isolate or a product that retains additional cannabinoids, you have a few options for the distillation process.
There are two different ways to go about distillation which vary in cost, technology, and scale—short path and wiped film. These two options have some similarities, but they have distinct differences that will impact which option is best for you.
Both options use vapor pressure (vacuum depth) to reach the lowest possible boiling points for our compounds to avoid degrading what we’re trying to capture—so either way, you’ll end up with a high-quality end product.
So what are the differences and similarities between short path and wiped film distillation? Let’s dive in.
Short Path Distillation vs Wiped Film Distillation
Short path distillation produces a high-quality distillate, but is limited in scale. Wiped film distillation is a variation of short path distillation that reduces the exposure time of the crude oil to heat and can increase productivity.
Short path distillation utilizes an apparatus with a multi-position receiver and condensing head. This process is very limited in scale and production, but can produce high-quality distillate with an experienced operator.
Crude oil is heated in a boiling flask with a magnetic stirrer. The condensing head is jacketed and requires a recirculating chiller to cool the condensing head to condense the cannabinoid vapor back into a liquid form.
The compounds are then separated through slow thermal heating with precise and controlled temperatures. As you slowly raise the boiling flask temperature, you will get multiple fractions of the distillation—the higher you go, the different compounds you will be distilling, starting with highly volatile terpenes or solvent leftover at lower temperatures. Raising the temperature will create a new compound/fraction, and the multi-position receiving flask can be adjusted to collect the different fractions into different receiving flasks.
A short path will typically have 3 fractions—heads (terpenes and high volatiles), main body (THC/CBD), and tails (high boiling point cannabinoids).
Pros of Short Path Distillation
Short path distillation produces a high-quality product. You can get multiple fractions during the distillation process, depending on how high you raise the temperature. The multi-position flask collects the different fractions into different flasks, which allows for easy distillation.
Cons of Short Path Distillation
Like most distillation processes, short path requires an experienced operator to efficiently get a high-quality product. It is limited in scale and production, so it’s not ideal for large-scale operations.
Wiped film distillation is a variation of short path distillation, which can operate in batches or continuous modes. The operation process is simple yet effective. It’s well suited for high production/scale and high throughput because it uses a continuous feed compared to the short path method.
While under vacuum, the crude oil is added to the top of a heated vertical cylinder on a rotating plate. Specially designed wipers wipe the oil, thus creating and renewing the thin film. This thin film enables an efficient heat transfer, even for highly viscous fluids.
As the oil enters the cylinder, it encounters the rotating, specially designed wipers or rollers that create and renew a thin film on the heated surface. A long, condenser in the middle of the wipers in the evaporator body, cooled with recirculating fluid, condenses the vapor. Receiving vessels collect the distillate and the high temperature residue at the bottom. A recirculating heater provides temperature control of the feed container and outer jacketed wiped film evaporator body. Refrigerated circulators cool the condenser and cold trap. Optimizing the feed rate, vacuum, and temperatures is essential to yield the desired component composition in the distillate.
This method reduces the exposure time of the oil and can increase productivity if it is run in a continuous mode. With a wiped film extraction, you will need to run two passes through the system to achieve a distillate. As in distillation, you are stripping the crude of low boiling point compounds first, for example, terpenes and leftover volatiles. You would then run that residue again to achieve the final distillate.
Pros of Wiped Film Distillation
Wiped film has an extremely efficient and even heat transfer due to its thin film of oil, no matter how viscous the fluid is. This results in a high-quality product. The process can easily be used for large-scale productions, so it’s ideal for large batches of distillation. If you run in a continuous mode, it also reduces the exposure time of the oil and increases productivity.
Cons of Wiped Film Distillation
Two passes are required through the system to achieve a high-quality distillate. After the first pass, there are still some leftover terpenes and volatiles. The second distillation requires a little more time, but results in a higher-quality end product.
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