Since the early days when hashishins began making solventless cannabis concentrates using the ice water extraction method, ice cubes have been an integral part of the process. Hash makers add ice cubes to a mixture of water and cannabis material to keep the temperatures near-freezing inside the washing vessel. The colder the water, the better (up to a point). 

So why do hash makers use ice cold water for washing hash? Cold water makes the trichomes brittle enough to cleanly break free from the cannabis material, while also remaining intact as carriers of the valuable resin contained inside. Warmer water softens the protective membrane around trichome heads, making them more liable to rupture and release their precious oil. 

The ideal water temperature for washing hash is 32 F. Ice helps keep water as close to freezing temperatures as possible. However, it is possible to overdo it, to. There is a certain way to use ice, and a certain type of ice to use, in order to produce the best results. 

Before we get started, a note about cold rooms. Getting your ice dialed in is very important, but washing hash in a warm environment is like fighting with one hand tied behind your back. 

Creating a dedicated cold room for working with hash is the best option for serious extractors. Converting an existing room in your home into a cold room is probably the most cost-effective option. But, if you have the budget, a stand-alone cold room in the backyard will give you the ultimate flexibility in design and buildout. 

Check out our article How To Build a Cold Room for Washing Bubble Hash.

How Much Ice To Use 

We want to use enough ice to keep the water near freezing, but not so much that it crowds the vessel. As long as you’re achieving a visible vortex in the water while mixing, you’re on the right track. The key to mixing is creating and maintaining a vortex in the ice water and cannabis slurry. 

Aim for 7-10 lbs of ice per 5-gallons of wash bag capacity. However, if you’re using an insulated washing vessel and working in a space that’s under 40 degrees F, you can reduce your amount of ice by half or more. 

Too much ice also leads to overcrowding in the mixing vessel. Overcrowding with ice hampers the vortex effect created while stirring the water and cannabis material together, and it’s the liquid vortex that does most of the work of separating trichomes without releasing a lot of plant contaminants along the way. 

What Type of Ice

Water for Ice

First, let’s discuss what type of water to use for your ice. The worst kind of water to use for ice cubes is tap water, which contains chemicals like chlorine. We don’t want Chlorine in our hash, so we avoid it in our ice. Therefore, ice cubes that your freezer makes with tap water at home is not a great idea. 

The best water to use for washing hash is RO water, and theoretically that’s also the best to use for making ice cubes. If you’ve got an ice maker in your lab and you can hook it up to your RO filter line, that would be ideal. 

However, for most people, using ice cubes made with clean, filtered water is a great choice. Filtered water is better than tap water, and you can purchase ice cubes made with filtered water at the store. 

Keep in mind that clear ice is a sign of purity. Clear is good. Cloudy ice signals the presence of impurities. Clean ice that doesn’t contain impurities melts slower than ice containing impurities, and you should always avoid ice that looks very cloudy. 

Size of Ice Chunks

The best type of ice to use - size between 1 and 1.5-inches in diameter. Don’t use anything larger than 2-inches in diameter. Large pieces of ice slam into each other with too much force, which can pulverize the material, leading to contamination in the hash.

If the ice pieces are too small they present a couple disadvantages: 1) they melt too quickly 2) they float on the surface of the water, rather than submerging in the water. Plant material also floats, competing with the same space as the ice. This can cause an over-agitation of the plant material while mixing. 

Shape of Ice Chunks

Bullet ice and ice cubes are both a good choice for washing hash. Bullet ice has an elongated cylindrical form that was designed for faster cooling and slower dilution in liquid. Bullet ice allows for extended chilling without excessive melting.

Flakes, nuggets, and micro chewblet ice measure approximately 3/8” (0.95 cm) long. Since they’re less than 1 inch in diameter, avoid these forms of ice.

Ice To Avoid

Dry Ice…don’t use it! Although it’s colder than regular ice, it’s counterproductive to producing the cleanest hash. The ideal temperature for ice water extraction is 32 degrees F, and dry ice is too cold to hit that mark. Dry ice is about -78 degrees F, and that’s way too cold for ice water extraction. We’re aiming to make the trichomes brittle so they cleanly break away from the plant material, and we don’t need dry ice to do that. 

Don’t use ice blocks in the washing vessel. Ice blocks are way too big and they hamper the ability to create a vortex. However, ice blocks can be used for pre-chilling. 

Pre-chilling your water is necessary, as you need ice cold water to add to the washing vessel. Don’t put lukewarm water into the washing vessel. Large pieces of ice melt more slowly, so this can be an advantage when pre-chilling large amounts of water. Remember, even if you’re using ice in your washing vessel, you still need to pre-chill your water. 

Read more in our article How To Keep Your Water Cold for Ice Water Extraction.

Wash Vessel Insulation

Creating a layer of insulation around your wash vessel keeps the water colder for longer. Insulating the washing vessel, whether it's an automatic washing machine or a vessel for hand mixing, helps minimize the amount of ice needed. Less ice means less abuse of delicate trichome heads. This not only improves your results, but it keeps costs lower too, with less ice to produce or buy. 

The Press Club’s Washing Vessels come pre-installed with insulators so you don’t need to worry about fitting something after-market.  

Read more about insulation in our article Bubble Wash Insulation Guide.

Conclusion

Near-freezing temperatures are necessary for ice water extraction. It’s easy to add more ice cubes to the washing vessel throughout the process, and ice can be used in place of an expensive water chiller. That said, ice is not absolutely necessary. No ice tech is another option that some hash makers are moving towards. 

Read more in our articles No Ice Tech: The Future of Solventless and Ice vs Iceless Hash.

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