How To Air Dry Bubble Hash

Viviane Schute        

Cannabis enthusiast and student of the art of solventless extraction


Drying is an essential phase in the creation of high quality bubble hash. Bubble hash is made through a process called ice water extraction, in which extractors mix cannabis and ice water together causing trichomes to fall away from the cannabis material. Extractors then filter these trichomes through a series of screens known as bubble wash bags, in order to separate the full trichome heads from the starting material. 

The main determination of the quality of bubble hash is the overall quality of the cannabis starting material. The extractor’s skill in isolating and collecting only the trichome heads without excess plant contaminants, like tiny pieces of green material and trichome stalks, also determines bubble hash quality. 

Another factor that’s sometimes overlooked regarding the overall quality of bubble hash is the drying process that’s used after production. Bubble hash is completely saturated with water right after it’s extracted. 

Properly drying the hash not only prevents it from being ruined with mold, it helps bring out its finest qualities.




But drying hash hasn’t always been necessary, because hash hasn’t always been made with water. People have been making hash in some form or another for thousands of years. It wasn’t until the end of the 20th century that the ice water extraction method came onto the scene. Once this innovation was employed, the techniques to thoroughly and efficiently dry bubble hash also began to develop. 

Regardless of the intended use, whether in preparation for smoking, dabbing, aging, or pressing rosin, it’s essential to dry bubble hash after ice water extraction. 

Fortunately, drying bubble hash doesn’t require a lot of tools or equipment. Although high tech drying equipment does exist (and is arguably the best option to give you ideal results), it’s possible to make premium hash that’s air dried on a piece of parchment paper and cardboard. 

Different methods of drying bubble hash call for varying levels of environmental control. For example, using a freeze dryer to dry bubble hash is a totally automated process that requires very little input from the extractor. But with air drying, it’s essential for the extractor to carefully control the preparation of the hash, temperature, humidity of the drying environment, etc. 

The technology of a freeze dryer pulls moisture from the inside of a wet batch of hash, drying it thoroughly and quickly via sublimation and a vacuum. This means that moisture locked inside the center of a thick layer of wet hash can be quickly and completely removed. However, when air drying, moisture needs to naturally evaporate away. Moisture inside thick patties of wet hash can get locked inside and lead to mold growth, which ruins the hash. This is why extractors break the wet hash into tiny pieces and spread it out in a very thin layer to air dry. 

Moisture leaves bubble hash through a process of either evaporation or sublimation. Evaporation happens over the course of several days when bubble hash is exposed to air. There are different approaches to letting bubble hash air dry, including within a cold room or wine cooler. There are also different ways to prepare hash for air drying.

Sublimation happens within a freeze dryer, and it’s a more expedient way to dry bubble hash. Although freeze dryers tend to deliver consistently better results, air drying hash is still a feasible way to get an excellent full melt product. 

Let’s take a look at the different techniques used to dry bubble hash. 

Air Drying

Air drying is a straightforward approach to drying bubble hash. Hash is collected from the bubble wash bags in totally saturated globs of trichomes. These wet hash patties are placed on a 15 or 25 micron screen and then lightly patted to coax out some water. After the extraction is complete, the hash goes into the freezer for 24 hours until it's completely frozen. 

After the fresh and wet hash is frozen solid, the hash patties need to be broken apart into tiny pieces to allow moisture to evaporate more quickly and completely. If the hash isn’t broken apart and scattered in a thin layer, water will get locked inside the mass of trichomes and potentially lead to mold growth. The hash dries in a thin layer over a piece of parchment paper. Underneath the parchment is a piece of cardboard that acts as a desiccant, pulling moisture out of the hash. 


There are two main ways to grind the frozen hash apart: microplaning or sieving. A microplane is a kitchen tool traditionally used for zesting lemons and grating cheese. Microplaning involves scraping the hash over the surface of the microplane to grind it into small pieces. Those tiny hash granules are spread out in a thin layer on top of the parchment paper. 


A sieve is another kitchen tool that doubles as a great piece of equipment to help with drying bubble hash. Sieves look like bowl-shaped stainless steel screens with a handle. Extractors rub the frozen hash back and forth over the sieve, which breaks it apart as the hash passes through and drops onto the parchment paper. Sieving is a gentler way to break apart wet hash in preparation for drying, as it’s less likely to rupture trichomes than microplaning. 


Read more in our article The Difference Between Microplaning and Sieving for Drying Bubble Hash.

Once the bubble hash is grinded down into small pieces and spread on top of parchment paper over a piece of cardboard, the question becomes where to place the hash to air dry. Environment is critical. 

For air drying bubble hash, the ideal environment is 35% relative humidity at 55 degrees Fahrenheit. 




A cold room with air conditioning and humidity control will work beautifully. There’s no need for anything fancy, just clean, cool, and relatively dry air. 

Wine coolers are another way to control the environment for air drying bubble hash. You can place the sheets of hash on the racks of a wine cooler and monitor the temperature and humidity inside. Wine coolers can be good if you live in a hot and dry area and have trouble setting up a cold room. 

Read more in our article How To Use a Wine Cooler to Dry Bubble Hash.

Regular refrigerators are a decent option too, if you have trouble setting up a dedicated cold room. Just beware of odors inside the refrigerators, as this has the potential to impart some undesirable qualities to the smell of your hash. 

For more info on air drying bubble hash, check out Best Ways To Dry Bubble Hash.

Freeze Drying

Freeze dryers offer extractors the ideal bubble hash drying solution. Freeze dryers reduce the amount of oxidation that hash undergoes during the drying process and thoroughly dries the hash in about 24 hours only. This is a fully automated solution that doesn’t require breaking the hash into small pieces for drying, so it saves time and effort on multiple fronts. Freeze dryers freeze the wet hash first, then warm it back up inside of a vacuum chamber. The vacuum pulls moisture from inside the wet hash patties. 


Freeze dryers eliminate moisture from the inside out, preventing any wet pockets from remaining in the hash. Areas of moisture can harbor mold, so fully removing all moisture is a big win. They also minimize operational space, because the hash doesn’t have to be spread out so thinly over a large surface area in order to effectively air dry. Instead, it stacks on top of racks inside the compact freeze dryer. 

After the wet hash is collected, place it on a baking sheet on top of parchment paper. Then slide the baking sheets into the freeze dryer. No need to cardboard as with air drying hash. One good tip is to make the wet patties all the same thickness before they go into the freeze dryer. This is the extent of the prep work needed for drying with a freeze dryer.  

In summary, freeze dryers save time and labor, reduce oxidation, and more thoroughly dry bubble hash. They also cause less structural damage to the hash than other methods would entail, like grinding with a microplane.   

Read more in our article How A Freeze Dryer Works. 


Using the right techniques to dry bubble hash is as important as using the right techniques to extract it. Drying hash incorrectly can lead to mold growth which totally ruins the product. A good drying process maintains the quality of the hash by minimizing oxidation while allowing the hash to thoroughly dry. For air drying, this requires breaking the wet hash into small granules then scattering it in a thin layer over parchment paper and cardboard. Freeze drying allows extractors to skip this step and offers a fully automated solution. If you have the budget for it, freeze dryers are the way to go. 

Want more tips on how to dry bubble hash? Check out our article Top 5 Bubble Hash Drying Tips.

Thoughts? Let us know by joining our secret Facebook group. Hang out with a community of like-minded solventless heads like yourself. Ask our head extractor questions, share your latest press and learn from hobbyists and experts in the industry.


Do you have to dry bubble hash?
Yes, bubble hash that's made with the ice water extraction method needs to be thoroughly dried before use. 

What is the best way to dry bubble hash?
Freeze dryers are the most ideal way to dry bubble hash, however air drying can also give you great results. 

What happens if you don't properly dry bubble hash?
If you don't properly dry bubble hash, it will likely harbor mold growth which destroys the product. 

Can you press wet bubble hash into rosin?
No, wet bubble hash can't be pressed into rosin. It needs to be dried first before pressing. 

How does a freeze dryer work?
Freeze dryers use the natural process of sublimation coupled with a vacuum chamber to efficiently dry bubble hash. 



Bob Rafto

I made some bubble hash and noticed that the residue water that I was going to throw out had brown particulates throughout the water.
I proceeded to boil the water to evaporate to see if the particulates remained.
As the water started to boil, trichomes in bubbles floated to the surface, which I scooped out and collected a small amount of hash.
When the water evaporated, the particulates turned into a crude black hash oil.
I would dearly love to know if this oil that I made has medicinal qualities and if this is another method of producing oil.


How long do you air dry the hash once you have it broken down on parchment paper and on cardboard? Hours? Days? How long?


Can the freezer be used to dry the dry sifting so that it becomes easy to collapse without a lighter


Actually the freeze dryer sounds like a nice device to have, but essentially all you need is a vacuum pump. The vacuum pump lowers the pressure which you the negative pressure to lower the boiling point of water which causes it to become a vapor water which will leave the container. I wrap mine in a triple layer of parchment paper so it’s not sucked out with the vapor. Of course you’ll need a container which can spend the negative pressure of which I use a glass vacuum container for labs. Some of the vacuum chambers that labs use will allow you to use a very fine mesh screen / filter, then you will need the parchment paper and you can put your product directly on the screen, with the right screen size it won’t be sucked out.

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