Flower Pressing: How Rosin and Other Cannabis Concentrates Are Made

Flower pressing applies heat and pressure to dried buds to squeeze out their oils, terpenes and cannabinoids without any solvents. The result is a potent concentrate like rosin or pressed hash, and you can make it at home or with commercial gear.

Pressing cannabis flower is a traditional technique for extracting resin and making concentrates like hash or rosin. The process applies heat and pressure to dried flower to release its essential oils, terpenes and cannabinoids, giving you a potent, aromatic concentrate.

Flower pressing has evolved over the years, picking up more sophisticated methods that deliver high-quality, solventless products. Below, we walk you through the steps and tools involved in pressing flower and getting the best results.

How are cannabis concentrates made?

Cannabis concentrates can be made commercially with advanced equipment or at home with simpler but equally effective methods. There are several approaches, each with its own techniques and tools. Some of the most common are:

• Dry sifting
• Dry ice extraction
• Ice water extraction
• Heat and pressure (rosin pressing)

One of the most widely used methods in the industry relies on flammable solvents, because they produce concentrates with very high THC levels. These products tend to deliver longer-lasting effects, which makes them popular with consumers.

Butane is one of the most common solvents, and using it gives you BHO (butane hash oil), an extremely potent concentrate that's cost-effective to produce.

What do pressed concentrates look like?

Depending on the method, cannabis concentrates can come in several forms:

• Runny, sticky wax
• A soft solid with a lip balm-like texture
• A hard, amber-colored solid

These products can be consumed in different ways. Waxes and oils are commonly used in vape pens, while solid forms are vaporized on a hot surface, usually a nail made of titanium, quartz or ceramic.

That process, known as “dabbing,” means inhaling the vapor through a special device called a “rig,” which is basically a water pipe built for the job.

Concentrates vs. extracts vs. dabs: what's the difference?

The terms used for these products vary and often get used interchangeably. “Concentrates” is a broad term covering every product derived from the cannabis plant this way. Some people, though, draw a line between “extracts” and “concentrates.”

Extracts usually means products made with solvents, which leaves out anything made with solventless methods. Meanwhile, “dabs” can refer specifically to products like BHO, though it's sometimes used more loosely for any kind of concentrate.

On top of that, there are post-processing steps that can modify these products even further, creating more variations and adding even more terms to the vocabulary.

What effects do pressed concentrates have?

Using cannabis concentrates has been linked to a number of adverse health effects, although more research is needed to fully understand how those effects differ from smoking dried flower.

• Cannabis concentrates contain extremely high THC levels, especially the ones made with solvents.

• Studies have documented THC concentrations ranging from 54% to 69%, with some reports above 80%. By comparison, average THC in dried flower is significantly lower, sitting a little above 15%.

• Concentrates carry extra risk because each hit delivers a large amount of THC all at once. THC floods the body quickly and in very high amounts, which raises the risk of physical dependence and addiction.

• On top of that, high doses of THC are more likely to trigger anxiety, paranoia and psychotic episodes, although more research is needed to fully understand these risks when it comes to concentrates.

Contaminants in cannabis concentrates

Cannabis bud concentrates aren't just potent in THC terms; they can also contain contaminants that pose health risks. One study found that 80% of the concentrate samples tested were contaminated, not only with pesticides (also a concern in dried flower) but with residual solvents that weren't fully purged during production.

For example, people who use butane hash oil (BHO) may be inhaling butane and other impurities along with the vaporized THC. Inhaling concentrated butane directly is extremely dangerous and has caused deaths, but the long-term effects of inhaling butane residue or other contaminants in cannabis concentrates still aren't clear.

The risks of making concentrates with solvents

Making concentrates with flammable solvents like butane comes with serious risks. There have been plenty of house fires and explosions caused by people using butane to make extracts, leaving the people inside with severe burns.

A 2015 study on cannabis legalization in Colorado found a sharp rise in burns from explosions linked to butane THC extraction, some covering more than 70% of the body and requiring skin grafts.

Making butane hash oil is illegal under US federal law, as is all cannabis manufacturing. Even in states where cannabis is legal, like Colorado and California, making hash oil with flammable solvents outside a licensed facility is against the law.

State authorities recommend safer alternatives like dry ice (CO2) or ice water methods, or buying concentrates from licensed shops that use controlled, safe extraction systems.

These safer setups keep the solvents from escaping or being exposed to the air, where they could accidentally ignite, much like the procedures used to make other commercial products for decades.