Freeze drying, also known as lyophilization, is a low temperature dehydration process that involves freezing the loose resin and lowering pressure, removing the ice by sublimation. Sublimation is better than regular dehydration or air drying, because it does a better job of preserving terpenes and reducing oxidation. 

While it’s possible to make excellent hash with the air drying method, freeze dryers offer indisputable advantages for extractors processing loose resin at scale. 

Freeze dryers are one of the main pieces of equipment that solventless extractors use in their commercial labs. Many home hobbyists can also benefit from having freeze dryers at their disposal. They’re easy to obtain too, and aside from the relatively steep up-front investment, the downside to using them is negligible. 

How Does a Freeze Dryer Work?

Freeze dryers use the process of sublimation to quickly and thoroughly remove moisture from loose resin. Sublimation is the magic behind the freeze dryer, as it is a much more efficient and complete way to dry hash than the process of evaporation. Air drying hash relies on evaporation only, as water does not sublimate in the environment used to air dry hash. 

Read more in The Difference Between Air Drying and Freeze Drying Bubble Hash.

First, a freeze dryer freezes the loose resin completely solid. Then, heat is applied and pressure is lowered to create a vacuum inside the freeze dryer. As the hash begins to warm, the water sublimates in this vacuum environment. 

Freeze dryers are able to remove 96-99% of the water in freshly-collected loose resin. 

Read more in How Does a Freeze Dryer Work? 

Let’s take a look at how solventless extractors can use basic freeze dryers to dry wet trichomes, including some special tips that are unique to working with resin. 

Supplies for Freeze Drying

How To Properly Use a Freeze Dryer to Dry Bubble Hash

1. Make sure the freeze dryer is up to date. Read about firmware updates for your Harvest Right in Harvest Right Pharmaceutical Firmware 4.0.56 - Required Update For Home Freeze Dryers.

2. Set the following parameters on your Harvest Right:

• Switch the ‘dry’ option from ‘sense’ to ‘time’.
• Set time to 24 hours for single-shift operations, and 12 hours for multiple shift operations.
• Set freezing temperature to -30f and shelf temperature to 35f. The update you ran earlier will allow for this adjustment. 
• Freezing time can be set to 1 hour or the length of your wash cycle.
  

3. Place empty trays in the freezer, pre-chilling to -30f during the wash cycle. Pre-freezing the trays will prevent warmer ambient air temperatures from compromising terpene content in the resin later on in the process. 

4. After fully rinsing the loose resin at the bottom of the sieving bags for Ice Water Extraction, it’s time to think about fully and thoroughly wetting the resin as it sits in the trays. Dry trays are not conducive to an even and thorough drying process. We want the resin to be sopping wet throughout. 

5. Select a container with a diameter that matches your collection bag, and stretch the bag over the vessel. Leave a shallow dip so the resin sinks to the middle. Add some cold, fresh water to the slurry while the resin is on the bag, which will help it to remain fully saturated. 

An option is to add ice underneath the bag to help deal with higher environmental temperatures.

6. Load the trays with the wet resin, removing one tray at a time from the freezer. Only remove each tray when you’re ready to fill it, so everything stays as cold as possible. Scoop the resin up gently and work swiftly. Keeping everything cold is key. Maintain even saturation from tray to tray. 

7. No need to use parchment paper. The heating element in the tray produces very little warmth, and the conductive nature of the steel trays transfers that limited warmth inside the vacuum chamber. Parchment, which is an insulator, inhibits this, and actually increases the drying time. 

8. To hasten the defrosting process, you can remove large sheets of ice by hand. This can reduce the 1 to 2-hour long process to a 20–45-minute process. 

After the ice has been removed, seal the dryer, and complete the program to return to the starting screen. Press the logo on the top left-hand corner to enter the analog testing screen. This screen will display on/off options for–tray heater-refrigeration-vacuum-. Start the refrigeration first, wait a moment or two for the temperature to go down, and then start the vacuum. 

The unit will soon be chilled again, free of ice and ready to use in a shorter period than using the general defrosting program.

9. Allow the trays to cool past the shelf temperature at the end of the run, so the resin will not stick to the tray. A paint brush becomes a very efficient tool for removing any remaining trichome heads.     

10. After loading all your trays for the freezer, let them stay in the freezer for a long and slow deep freeze. It’s okay to leave these trays in the freezer for an extended time, as you have the capacity to run them through the freeze dryers. 

Leaving the wet trays in the freezer also allows smaller ice crystals to “anneal” and grow larger and less dense, which speeds up the actual time in the dryer. Smaller ice crystals are more dense and take longer to thaw. 

11. After 15 minutes in the freeze dryer while the walls of the machine cool, press the harvest right leaf logo in the top left corner of the display.

12. As the cycle is complete, open the dryer and check each tray for ice. Running a dull blade vertically down the trays is a good method for doing this. As long as there’s no ice, place the trays back in the dryer momentarily. If the cycle has just recently finished, this allows the plates to return to below freezing temperatures, along with the resin.

13. Set up your steel bowls, brushes, sieves and final container on a clean, flat surface. 

Benefits of Using This Process for Freeze Drying

Pre-freezing the trays of loose resin in a standing freezer means the Harvest Right unit only requires about 15 minutes of refrigeration time to cool the walls of the vacuum chamber, instead of needing to freeze the resin. Simply load the trays in after 15 minutes and press the harvest right leaf logo in the top left corner of the display.

This triggers the ‘vacuum freezing’ program. As the tray is properly frozen, there should be no issues. If you notice the hash seems to be rising like bread during this program, cancel and allow the product to freeze more thoroughly.

Dry times should be reduced to 12-16 hours, which can increase production volume week over week. 

Summary

Freeze drying, also known as lyophilization, has advantages over traditional air drying methods in the process of making bubble hash. Freeze drying involves freezing loose resin, lowering pressure, and removing ice through sublimation, offering superior preservation of terpenes and reduced oxidation compared to air drying. Freeze dryers can remove 96-99% of water from freshly-collected loose resin. 

The process involves freezing the resin solid, applying heat and lowering pressure to create a vacuum, leading to sublimation of water in the resin. Pre-freezing trays, maintaining even saturation, and avoiding the use of parchment paper offers several benefits, such as shorter dry times (12-16 hours) and increased production volume week over week.

Follow this process and let us know what you think!

Also check out:

How To Properly Maintain and Clean Your Harvest Right Freeze Dryer
Top 5 Tips For Getting Started With Your Harvest Right Freeze Dryer

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