Cannabis enthusiast and student of the art of solventless extraction
Rosin extraction is the art of squeezing trichomes out of cannabis material. It requires no solvents or other chemicals to create, and relies on a mechanical process composed of a trifecta of inputs: pressure, heat, and time.
It seems intuitive to many beginners in rosin extraction that more pressure produces better results. But we quickly discover that in reality this just isn’t the case. When it comes to pressing rosin, more is not always better. Sometimes less is more.
What exactly is pressure? Pressure is defined as the amount of force applied to the surface of an object divided by the area of the object over which that force is distributed. Force can be measured in pounds, or tons, which is not the same as pressure. This is a key distinction to keep in mind.
The surface area of any object receiving an application of force (measured in pounds or tons) determines the total amount of pressure being exerted upon that object’s surface. In rosin, we measure the force created by the rosin press applied over the surface area of the rosin bag. This gives us the measurement of pressure on the source material.
How is Pressure Measured?
Pressure is measured in pounds per square inch, or PSI. Stated another way, PSI is the number of pounds of force being applied to the area of an object in square inches. In rosin, the force that we’re generating is coming from the press, and the area over which that force is being applied is the rosin bag.
Why Is Pressure Important to Rosin Extraction?
Pressure, temperature, and time and the three main variables to consider in rosin extraction, in addition to the type and quality of starting material. Heated rosin plates provide high enough temperatures for the oily trichomes in cannabis to liquefy. It’s up to the extractor to apply the right amount of pressure to drive the concentrate through the filter bag and away from the plates. Various types of cannabis source material do best under different amounts of pressure, so adjusting for source material is always part of the equation.
Whether using a manual, hydraulic, or pneumatic press, understanding the responsiveness of the setup and being able to dial in specific pressure settings are advantages for the extractor. Being able to replicate pressure inputs for the same source material will also contribute to very consistent results in the rosin.
How to Calculate Pressure
Calculating pressure isn't incredibly complicated, but it's not as easy as simply reading the gauge on your rosin press. The internal pressure gauge on a traditional H-Frame shop, which often is displayed in tons, is not enough by itself. The same goes for pneumatic presses which display PSI on their gauges. We need to go deeper to find the pressure being exerted on the source material.
There’s a difference between measuring the amount of pressure at the rosin bag and the amount of pressure being generated within the press itself. The pressure on the source material is often called Platen PSI.
Platen PSI is the relationship between the dimensions of your rosin bag and the tonnes of force being applied.
The gauges on hydraulic presses for example, are measuring the hydraulic pressure being created within the press, and not the PSI being applied to the rosin bag. In order to find the actual amount of pressure being exerted at the source material, we need to calculate the Platen PSI.
The type of press you’re using will impact how the calculation is made. To help you quickly calculate the Platen PSI for your equipment, we did some of the heavy lifting for you.
To measure the amount of pressure on the source material, we calculate the relationship between the force applied in pounds for every square inch of surface area across the source material.
Platen PSI (pressure on source material) = Force exerted by press / Rosin bag surface area.
The calculations may feel daunting at first, but if we stick to this basic visualization of the total force from the rosin press divided by the surface area of the source material, we can get to a clear understanding of how much pressure is being applied to the cannabis during extraction.
The area of your rosin bag is a simple length x width calculation. The pounds of force exerted may require a couple additional steps, depending on the type of press you're using and its internal gauge.
Factors That Impact How Much Pressure To Apply
The three main factors to consider when dialing in your pressure settings include cannabis source material type, cultivar, and your preference for quality vs yield.
Different types of cannabis material yield optimal flows of rosin under different ranges of pressure. The three types of cannabis material we’ll consider are bubble hash, flowers, and dry sift.
Flower: 1000-2000 PSI
Bubble Hash: 500-1500 PSI
Dry Sift: 500-1500 PSI
In addition to the type of source material, the cultivar (cannabis strain) of the source material can impact the amount of pressure needed for optimal rosin production. The specific behavior of trichomes under heat and pressure varies between cannabis cultivars. Some strains are natural rosin gushers, others barely secrete any concentrate at all. Most cannabis is somewhere in between. Where the cultivar you’re using falls on that scale relates to how much pressure it will respond to best.
Lastly, your slant toward quality or yield can help guide your tendency toward more or less pressure. Less pressure used during extraction often produces cleaner rosin, in the sense that there can be less plant contaminants, lipids, and fats present. However, this comes at the expense of yield, as there is undoubtedly extra rosin left behind with the small amounts of lipids or other contaminants.
If maximum rosin output is your goal, you may gravitate toward applying more pressure during extraction. Increased pressure, while it does increase the likelihood of rosin bag blowouts, can help fully liberate all rosin that’s been liquefied within the source material. That means potentially more grams on your parchment.
The dynamics between temperature and pressure during extraction are mostly beyond the scope of this article, but the relationship between these two variables determines the quality and yield of your rosin. Generally, by using higher temperatures you can apply lower pressure, and visa versa. However, increasing temperature too drastically will also have its consequences, such as the potential to darken the color of the rosin.
Consequences of Too Much Pressure and Not Enough Pressure
Too much pressure can create a gusher effect with negative consequences, especially if the pressure is applied too quickly. Excessive levels of pressure are an invitation for blowouts, even when you’re using high quality bags. The idea is to apply just the right amount of pressure, as little as possible to achieve good results.
Too much pressure can also lead to a higher percentage of fats and lipids in the rosin. The best approach is to start with a low amount of pressure, and then gradually increase throughout extraction until you reach the maximum total pressure.
Not enough pressure can be problematic as well. Too little pressure can allow rosin to stay trapped in the starter material, rather than being fully squeezed out for collection. If not enough pressure is applied, too many trichomes remain bound to the source material. This means less rosin ends up in your jars.
There are no sure rules in specific pressure requirements. Experimentation is a great advantage if built into the process. It’s part of the art and part of the fun. And it always helps to have a good note taking system in place.
Knowing how to apply the correct amount of pressure to cannabis source material is an invaluable skill for solventless extractors.
Applying pressure within a given range based on source material type, and adjusting for the specific qualities of a given cultivar as well as the results you’re looking to achieve, will help you produce consistently high quality rosin.