Ice water extraction is the most effective and efficient way to collect loose resin from cannabis for making bubble hash or hash rosin. Hash makers mix ice water and trichome-rich cannabis material together to knock the trichome heads free, and then isolate those heads using a set of sieving screens, also called bubble wash bags. The trichome heads, or resin, is soaking wet when extractors collect it from the sieves. In this saturated state, it’s unworkable and prime for harboring microbial growth like mold and mildew. 

For making temple balls or hash rosin, only dry hash will do. Regardless of the end goal, the first thing hash makers need to do after ice water extraction is dry the loose resin. 

Different Ways To Dry Bubble Hash

There are two ways to dry loose resin following the ice water extraction process: air drying and freeze drying. 

Air Drying

Air drying is just what it sounds like, allowing moisture to escape the hash naturally through evaporation in the open air. After collecting loose resin from the sieving bags, hash makers freeze the resin then break it down into a sand-like consistency using a stainless steel strainer or microplane. Scattered in a thin layer over parchment paper and resting on top of a desiccant like cardboard, the hash will thoroughly dry over the course of several days. Environment is key, with the right humidity and temperature necessary to prevent excessive terpene loss and to minimize the risk of mildew and mold growth. 

Read more about how to air dry in our articles How To Air Dry Bubble Hash and What Is the Difference Between Microplaning and Sieving for Air Drying Bubble Hash?

Freeze Drying

Freeze drying utilizes equipment and technology that quickly and thoroughly dries loose resin. While air drying hash is possible through the process of evaporation, whereby liquid water turns into air vapor to escape the resin, freeze drying relies on the process of sublimation. Through sublimation, moisture within the hash is first frozen, then converts directly from a solid into a gaseous air vapor. Sublimation allows wet hash to dry from the inside out, and within about 24 hours compared to the many days it takes to air dry.  

Freeze dryers are specialized pieces of equipment that first freezes the loose resin, then slowly re-heats it within a vacuum chamber that completely removes moisture as the water transitions from solid into gas. This is the power of sublimation, coupled with vacuum technology. 

Freeze dryers are one of the most valuable pieces of equipment in a hash maker’s lab. If your budget can accommodate this investment, freeze dryers are worth every penny spent. 

Learn more about freeze dryers and how to use them in How Does a Freeze Dryer Work?

Advantages and Disadvantages of Air Drying and Freeze Drying

Air Drying

Let’s start by looking at the upsides and downsides of scattering wet hash over parchment-lined sheets of cardboard to air drying. 

Advantages

• No high-end specialty equipment needed, just a regular freezer, stainless steel kitchen sieve or microplane, parchment paper, and some cardboard. 
  
• Budget-friendly.
  

• Extended time in the open air can lead to excessive oxidation, imparting a darker hue onto the hash. 
  
• Volatile terpenes are lost during the air drying process.
  
• Takes several days to thoroughly dry the hash. 
  
• A proper cold room or drying environment needs to be set up for the proper temperature and humidity controls. 
  
• Higher risk of microbial growth in the hash while drying. 
  

Freeze Drying

How about doing it the easy way? It’s not all upside, so let’s look at the advantages and disadvantages of freeze drying. 

Advantages

• Thoroughly dries hash in 24 hours.
• Minimizes terpene loss and maximizes clarity of color. 
• No need to prepare the loose resin after ice water extraction, just scoop it onto parchment-line drying trays. 
• No need to set up a cold room for drying. 
• Freeze dryers only take up a small footprint, freeing up more operating space in the lab. 
• No risk of microbial growth in the hash while drying. 
• Consistent, even, and thorough drying every time. 

• Freeze dryers are expensive pieces of equipment that need to be cleaned and maintained regularly. 
• Might be overkill for home hobbyists and small batches of hash. 

All things considered, freeze drying is the ideal way to dry bubble hash. The advantages of using a freeze dryer far outweigh the disadvantages. Freeze dryers do a better job of preserving terpenes, minimizing oxidation, and preventing the type of microbial growth that can happen during the days-long air drying process. Freeze drying loose resin will deliver a higher-quality hash than that same resin left to air dry. 

Conclusion

Hash makers can achieve great results from both air drying and freeze drying loose resin. Either approach is a good option, although freeze drying is better in a side-by-side comparison. 

The key with air drying is thoroughly breaking apart the hash into a sand-like consistency for drying. Freezing the wet hash and then passing the hardened chunks through a stainless steel sieve is a great way to accomplish this. The drying environment, or cold room, is another critical factor in air drying. Frenchy Cannoli recommended 35% relative humidity at 55 degrees Fahrenheit in the drying room. 

Freeze drying is straightforward and the equipment is easy to operate. We recommend going with a pharmaceutical grade Harvest Right Freeze dryer and cleaning the machine after every use. 

Read more about freeze dryers and how to maintain them in these articles:

What's the Difference: Home vs. Pharmaceutical Harvest Right Freeze Dryers & What We Recommend For Drying Bubble Hash

How To Properly Maintain and Clean Your Harvest Right Freeze Dryer

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FREQUENTLY ASKED QUESTIONS

Why do you need to dry bubble hash? 
Loose resin is soaking wet after ice water extraction. In order to be pressed into bubble hash and temple balls, or made into hash rosin, hash makers need to remove this moisture.

How do you air dry bubble hash?
Hash makers freeze the loose resin, grind the hardened chunks through a stainless steel sieve, scatter the sandy-like hash over parchment paper-lined cardboard, and leave this in a cold room to dry in the open air over several days.

How do you freeze dry bubble hash?
Freeze drying bubble hash is easy. Just scoop the wet hash onto parchment paper-lined drying trays and slide them into a freeze dryer. Be sure the machine is adjusted to correct settings for drying hash.

What kind of freeze dryer do I need to dry bubble hash?
We recommend the pharmaceutical grade Harvest Right Freeze Dryer.

What is better air drying or freeze drying bubble hash?
While both methods can deliver great results, freeze drying hash is the preferred way to preserve terpene content, minimize oxidation, and prevent microbial growth.