What Is Ice Water Extraction?

Sophia Delphi May 16, 2022 - 8 min read
Fact Checked
Ice water extracted Hash

In recent years, one of the “big things” in the weed world has been BHO, a favorite of those who enjoy dabbing.

BHO, or butane hash oil, is a potent cannabis concentrate manufactured with the help of the flammable gas butane as a solvent. Butane is able to efficiently extract weed’s THC, other cannabinoids, and terpenes.

There’s just one problem: butane is difficult to remove from the finished concentrate. Despite producers’ best efforts, traces of butane often remain in the BHO — and state-required testing of concentrates for contaminants like butane can be shaky, to put it nicely.

That’s why older methods like ice water extraction are making a comeback.

The process is one of the few ways that users can make their own concentrate at home. But even cannabis producers are taking a new look at ice water because it creates a clean, uncontaminated concentrate that’s almost as potent as BHO.

Let’s explore.

What Exactly Is a Cannabis Concentrate

Most people smoke weed because of the psychoactive THC it contains. Medical patients smoke marijuana because the THC and other cannabinoids it contains provide medical or health benefits. Both groups enjoy the added benefits of marijuana’s terpenes and flavonoids, which provide flavor and aroma and boost the effectiveness of THC.

When all of those people smoke, though, they’re not just consuming the “good stuff.” They’re also smoking excess plant material like glucose and cellulose, as well as the potentially-hazardous chemical residue it creates.

By comparison, cannabis concentrates do just what their name says. They concentrate the cannabinoids and terpenes into a “cleaner” substance that’s most commonly used for dabbing, but can also be smoked or used in edibles.

And eliminating the extra plant components dramatically increases the concentrate’s THC content. Raw flowers may contain anywhere from 10-25% THC (occasionally a little more, depending on the strain). Concentrates, though, can be as much as 90%+ THC.

They have to be used with caution, but weed concentrates are vastly more potent.

How Concentrates Are Made and Extracted

There are two alternatives: with solvents, or without them.

Solvent Extraction

Solvents like butane are quite good at extracting cannabinoids and terpenes from cannabis, but the processes require expertise and complicated equipment to work well. There’s also the very real problem of removing the solvent from the concentrate after it’s produced.

Ethanol can also be used but it’s less efficient and doesn’t extract terpenes; it also leaves residue behind. The industry’s use of carbon dioxide as a solvent is growing in popularity because CO2 is clean and abundant. However, the required equipment is more expensive.

Ethanol can be used at home for extraction, but the final product won’t be as potent and the process can take months. CO2 extraction can’t be done at home. Butane and similar solvents are extremely dangerous (and often illegal) to use in DIY production.

Solvent-Less Extraction

The other option is so-called solvent-less extraction. The removal of trichomes containing THC and other desired compounds is done with mechanical processes and physics, instead of with solvents.

Hash used to be made very simply by farmers who rolled weed plants in their hands, collecting the sticky resin that collected on them and then compressing it. Even if it were modernized, that’s an inefficient method that can’t compete with today’s techniques.

Another method of extraction is almost as simple. Cannabis plants are shaken, causing the trichomes to fall off and drop through a series of screens. That resin is collected and then compressed if desired. A version of this approach, known as dry sift extraction, is commonly employed by end-users because it only requires simple, inexpensive equipment and it’s completely safe.

As we briefly mentioned at the start, the cannabis industry has taken a new look at one more of these solvent-less methods: ice water extraction. It doesn’t require high temperatures that cause weed components to degrade, and it doesn’t leave contaminants behind.

Ice water extraction isn’t being used extensively in commercial hash production just yet, but industry experts believe it may become more common over time. More importantly for our purposes, it can be done at home cheaply and easily.

What Is Ice Water Extraction and How Does It Work?

The concept behind this process is similar to the dry sift method we mentioned in the last section. Weed plants are agitated to cause their trichomes to fall off, and those resin glands are then harvested. The added benefit of putting the plant into ice and cold water is that they don’t affect the integrity of the cannabinoids and terpenes, as hot water might.

It could seem that using water to extract extremely small trichomes would be problematic. Wouldn’t they just float or dissolve?

Actually, they don’t. Resin glands are denser than water, meaning they simply drop to the bottom of the container. They then fall through special material designed to act like the screens used to make dry sift hash.

In the last few years, companies have started selling equipment that people can use to do ice water extraction at home. They’re cool, effective — and expensive. Bare-bones models start at around $500 and you can buy a high-end system for around $30,000.

Or you can spend a few bucks and do ice water extraction the old-fashioned way. It produces a potent concentrate called bubble hash.

How to Make Bubble Hash

You already have most of what you need at home: a bucket, water, and ice. We assume you also have weed, so all you’ll have to purchase are so-called micron bubble bags. You can easily find them online.

Bubble bags are a series of 4-6 bags with mesh bottoms; the top bag has the widest mesh openings (about 200 microns) and the bottom bag has the smallest mesh (50 microns or so). Most sets also come with a drying screen where you spread out the hash you produce.

The process is simple. The cannabis is frozen, so it won’t break and the trichomes will fall off more easily. It’s layered with ice in the top bag, cold water is added, and the mixture is allowed to get as cold as possible. (Thus, ice water extraction.)

The mixture is agitated with a paddle, a food mixer, or a power drill (with a suitable attachment). Trichomes will fall through the top mesh, probably along with some plant material; the resin glands that stick to the mesh are collected and put onto the drying screen, and the process is repeated with each of the remaining bags, in order.

The bubble hash will get purer and more potent as the product falls through each successive mesh net. The hash that collects on the final screen is known as a full-melt hash, and it’s likely to approach 50-70% THC content.

What can you do with it?

Full-melt hash is best for dabbing, because of its potency and purity. Bubble hash can be smoked, but there are better ways for smokers to make the most of it: add some bubble hash to weed and roll the mix in a joint or blunt, or top a bowl with a little hash. It can also be vaped with the right type of vaporizer or turned into edibles.

The BHO you can purchase at dispensaries may pack a little stronger punch, but you can’t beat the price — or the satisfaction — of making your own hash at home with ice water extraction.

Ice Water Extraction: FAQ

Q: Can you use raw weed instead of frozen weed for ice water extraction?
A: Yes, but you’ll have to be more gentle when agitating the bud, which means the process will take longer, and you’ll be more likely to wind up with plant material in your hash — at least in the first few bags.

Q: How much better is ice water extraction when it’s done in a dedicated machine instead of with a bucket and some bags? Is it worth buying one of the less expensive machines?
A: Your hash will almost definitely turn out purer when using a machine, with less possibility of plant matter making it into the final product. It will probably be more potent, too, although the difference shouldn’t be enormous if you use care with the MacGyver approach. As for whether it’s worth it to shell out five bills or more? That depends on how much hash you plan on making.

Mullins, M. F. (2021). Cannabis dabbing: An emerging trend. Nursing, 51(5), 46. [1]

Bidwell, L. C., YorkWilliams, S. L., Mueller, R. L., Bryan, A. D., & Hutchison, K. E. (2018). Exploring cannabis concentrates on the legal market: User profiles, product strength, and health-related outcomes. Addictive behaviors reports, 8, 102-106. [2]

Al-Zouabi, I., Stogner, J. M., Miller, B. L., & Lane, E. S. (2018). Butane hash oil and dabbing: insights into use, amateur production techniques, and potential harm mitigation. Substance abuse and rehabilitation, 9, 91. [3]