Top 5 Bubble Hash Drying Tips

Viviane Schute        

Cannabis enthusiast and student of the art of solventless extraction


Ice water extraction is the ideal method used to create high quality bubble hash. While other methods like dry sifting can produce excellent solventless concentrates, ice water offers extractors greater control over isolating trichomes and removing plant contaminants. But after extraction is complete a lot of water still remains, leaving a totally saturated patty of cannabis trichomes. Not only is the hash unusable in this state, but it’s vulnerable to microbial growth like mold. 

Just like fruits and other foods, bubble hash can invite microbial growth if there’s sufficient moisture present. Drying bubble hash after ice water extraction is an essential part of the hash-making process. Moldy hash is ruined hash, so the main concern when drying is to protect the hash from microbial growth. 

The goal with drying is to reduce water activity level in the hash down to .6% and below. Water activity levels above .6% produce an environment where microbial growth like mold can flourish. Once you’ve dried sufficiently, the hash will be protected from future mold growth while storing and aging. But what is the water activity level? Is it the same thing as moisture content?




Water activity level is not the same thing as moisture content. Water activity levels are a common measurement used by food brands that produce things like corn flakes, dehydrated fruits, pasta, etc. Water activity is a principle of thermodynamics that measures the energy status of water in a system. It’s a function of the movement of moisture within a substance, not the concentration of the moisture. The only way to measure water activity level is with an electronic meter. For most hash makers, the money that could be used for a water activity meter would be better spent on a freeze dryer. Freeze dryers ensure that bubble hash is thoroughly dried to safe levels within a short amount of time. 

When air drying as opposed to freeze drying bubble hash, it’s okay to go by touch. Properly dried bubble hash should feel sandy, leaving no moisture if squeezed between the fingers. Good hash may be sticky, but should not feel at all damp. 

Learn more about different ways to dry bubble hash in Best Ways to Dry Bubble Hash.

Here are some of our top tips for properly drying bubble hash, which can be one of the trickiest yet also most critical phases of production. 

1. Lightly Pat the Hash to Remove Excess Water using a 15 Micron Screen

Immediately after collecting hash from inside the filter bags using a cold metal spoon, scoop the wet trichomes onto a 15 micron screen. This size of screen allows water to drain through, but is too small to let trichomes pass. This allows some of the water to escape while the hash sits there, while also preventing the hash from getting through the screen. 

Fold the 15 micron screen in half so that the hash patty is between the two layers of mesh. Lightly press down on the hash to gently squeeze out any excess water. Be careful not to compact the hash too tightly as this will prove to be counter productive for the drying process. Lightly patting the patty will suffice. 

2. Sieve Inside a Freezer for Air Drying

After the bubble hash is collected and set out to drain on a 15 micron screen, it moves into the freezer assuming you will be air drying the hash. The hash patty needs to be frozen thoroughly before the next phase of the process, which involves breaking apart the hash into a fine granular consistency, like sand. This increases the surface area of the hash which allows for more efficient drying. 


Read more in our article that details the process of sieving bubble hash for drying.

One good trick for breaking down the frozen hash with a sieve is to work with the hash inside of a freezer. These frigid temperatures help keep the hash in a workable consistency. If the hash warms up while you’re trying to work in through the sieve, it will easily smear around and prove to be very difficult to force through the metal sieve. You can use a regular residential freezer for this, just keep the door open and hold the hash inside the freezer while you’re working it through the sieve. 

3. Use a Moisture-Absorber when Air Drying

For air drying, the hash should be broken apart with a sieve over a piece of parchment paper. But it’s not enough to place the parchment on top of a solid surface. It needs to go on top of some sort of desiccant, which is a moisture-absorbing surface. The most popular desiccant for air drying hash is a piece of cardboard. You can even put a towel over the cardboard, then place the parchment on top of the towel. Just be sure to check the towel often for excess moisture and change it out as needed. 

4. Create a Dedicated Drying Room for Air Drying


In order to create the ideal environment for air drying hash, setting up a dedicated room is your best bet. In addition to lightly patting the fresh hash and sieving it over a desiccant, placing it in a room with specific moisture and temperature will allow the bubble hash to dry thoroughly and efficiently. Often, an air conditioner and dehumidifier is needed to create the perfect environment. 

Aim for 35% relative humidity at 55 degrees Fahrenheit, with sufficient and indirect air ventilation. Keep in mind that strong air currents directed onto the hash can lead to unnecessary terpene loss. 

5. Form the Hash Patties into Consistent Shapes/Sizes for the Freeze Dryer

The last four tips pertain to air drying hash. This last tip is for those lucky enough to be drying with a freeze dryer. While the freeze drying process is automated to ensure quick and complete drying to levels that prevent microbial growth, there is one step of preparation that can make the process even more efficient. 

Forming the freshly-made hash patties into shapes with similar dimensions will ensure that all the hash dries evenly and consistently in the freeze drier. Rectangular shapes about a quarter inch thick tend to work nicely. 

If some of the hash is in a thick blob, some thin like a pancake, and some in a cube, there could potentially be different levels of dryness when it comes out of the freeze dryer. Try to keep the same overall shape and thickness when you’re putting a variety of hash patties in the freeze dryer.




Bonus: Buchner Funnel

The Buchner Funnel set up is a nice hybrid of the air drying and freeze drying methods. Like freeze drying, the Buchner Funnel utilizes a vacuum. But unlike freeze drying, it doesn’t rely on sublimation to eliminate moisture, rather moisture is pulled from the hash within a sealed funnel. Check out the video on YouTube called Removing Water from Ice Water Hash with the Buchner Funnel Technique that Shango Los from the podcast Shaping Fire put out recently. 


Drying bubble hash is necessary to prevent microbial growth and to prepare it for storage and aging, rosin production, or for smoking by itself. It’s not enough to leave wet hash in a giant, saturated mass out in the open air to dry. For air drying, the hash needs to be broken apart into small, granular bits and placed over a desiccant. For freeze drying, the hash should be formed into consistent shapes to allow for even and thorough drying. 

Freeze dryers are the best way to dry bubble hash, but they require a sizable chunk of most extractors’ budgets. The good news is, air drying hash produces phenomenal results too, if the right techniques are used. Keep these tips in mind for a thorough and efficient drying process. 

What tips do you have for drying bubble hash? Let us know in the comments!

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Do you have to dry bubble hash?
Yes, bubble hash made with the ice water extraction method is soaking wet right after production and needs to be properly dried. Drying prevents microbial growth (which will ruin the hash) and readies it for rosin production, storing/aging, or smoking by itself. 

What is the best way to dry bubble hash?
Freeze dryers offer the ideal way to thoroughly dry bubble hash, but air drying can deliver excellent results as well. Read more in our articleBest Ways to Dry Bubble Hash.

What is a Buchner Funnel?
A piece of laboratory equipment generally used in filtration, which can also be repurposed for drying hash. The wet hash is placed into the sealed Buchner Funnel, and a vacuum pulls the excess water out of the hash. 

What is a desiccant?
A desiccant is a substance used to absorb water. For drying hash, cardboard is commonly used as desiccant. The wet hash goes onto a piece of parchment paper, which is placed over a sheet of cardboard, allowing the cardboard to pull water out of the hash and through the parchment paper.

What is the best temperature and humidity for a hash drying room?
For air drying bubble hash, aim for 55 degrees Fahrenheit and 35% relative humidity in your drying room. 


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