Comparing 25°F and 40°F Shelf Temps

Comparing 25°F and 40°F Shelf Temps

Jun 19, 2024

We recently teamed up with one of our users to conduct a simple shelf temperature test. This initial experiment is part of a larger, ongoing investigation into the factors that influence hash quality and batch times during freeze drying.

Our goal is always to encourage an iterative approach to making hash. We aim to:

  1. Encourage a data-driven approach to freeze drying

  2. Provide a simple, replicable test that anyone can try at home

  3. Lay the groundwork for a more extensive study examining shelf temps across a wide range of batches, facilities, starting material and other variables

The Great Shelf Temperature Debate

Many in the hash community believe that lower shelf temperatures lead to better hash quality, as they are thought to preserve terpenes. However, we recognize that shelf temp is just one of many factors to consider.

Variables around process:

  1. Freeze times and their impact on primary/secondary drying characteristics

  2. Moisture content of your hash when scooping from bags to trays

  3. Tray loading and distribution

  4. Ambient room temp. and humidity

  5. Head sizes and resin type

Other things to consider that pertain to shelf temps:

  • Production requirements and turnaround times

  • How often you're able to check your freeze dryers

  • What your desired moisture content is at the end of drying (end product, starting material and overall tray load will also impact this)

  • Here's our best guess at explaining what's happening here and why there's a perceived quality difference with lower shelf temperatures:

    • Higher shelf temps dry faster than lower shelf temps

    • This means higher shelf temps could have a smaller 'sweet spot' for ideal dryness than lower shelf temps

    • Because most people don't have a consistent process for checking their freeze dryer batches, this leads to most hash becoming 'overdried' (as defined by the operator)

And to preface what we detail here and in our future experiments, we're not selling you classes, consulting services or magic tek. We encourage you to look at everything we say here with a critical lens and to go find answers for yourself. The only thing we advocate for is tracking as much data as possible. We build free and paid tools to make that process easier, but you don't need to use any of them to conduct these experiments.

We love to see so much knowledge being shared on Instagram, Reddit and the rest of the web. We'd love it a lot more if people recorded some of their data and observations for others to consume. One of the underlying objectives with this series of experiments is to provide a simple framework for people to start testing different drying techniques.

Freeze dryers are still pretty new to the game. It's incredible how far we've come in such a short amount of time. There's still a long way to go. Understanding variables that are easy to control on Harvest Rights, like freeze time and shelf temps, is logically the first step in uncovering the secrets of freeze drying.

There's also a lot to be said for what happens when it comes out of the freeze dryer — how you're handling the hash, curing it, whipping it, pressing it or doing whatever it is that makes your process unique. We encourage you to experiment and write stuff down. You're only as valuable as your next harvest or hash drop. Data is the underlying foundation that can make you consistently bring (and build) value.

Our Simple, Initial Test

We worked with Kooosher to test two different shelf temps, controlling all possible variables and only changing shelf temp while allowing for extended drying time if needed.

Chimera × SK (trim) 73-159u (1st, 2nd, 3rd wash)

For our experiment, we isolated the shelf temp variable as much as possible:

  • Used the same wash, at the same time, in the same run

  • Pre-froze both 50g samples on trays

  • Set one shelf to 25°F and the other to 40°F (typical range is 5-40°F, with 30°F being a common midpoint)

Starting material: Chimera × SK (trim)

What Kooosher Observed

Using HashyLink and their own observations during the process, Kooosher found:

  • The 25°F sample took 2 hours longer to dry than the 40°F sample

  • No significant difference in hash quality between the two samples

  • A slight difference in color, but this could be due to lighting and camera variations

25°F Shelf Temp Batch

40°F Shelf Temp Batch

Kooosher also noticed:

  • Visually, no difference between photos

  • Less clumping in 25°F because it was checked and partially sieved before going in for more dry time, while the 40°F has more clumps on tray because it was dried straight through and did not require any sieving/additional dry time

  • Color and texture were the same

  • Time to grease was the same

  • Any differences in color were likely due to lighting; impossible to say there are any differences from a visual standpoint

Exact times recorded with HashyLink

40°F took 17 hr and 31 min total (3 hr 45 min freeze time)

25°F took 19 hr 20 min total (3 hr 03 min freeze time)

The big difference is that the 40°F run finished in a single drying cycle. The more times you have to restart it, the more time your batch spends sitting around doing nothing.

Final rosin from the experiment

Hypothesis About What Could Be Happening

One potential explanation for why lower shelf temperatures lead to a perceived increase in hash quality could be the existence of an “optimal dryness window.”

Let’s use the example of reverse searing a 1.5-inch thick steak to illustrate this. When reverse searing a steak at 250°F, it takes approximately 45-60 minutes to reach an internal temperature of 125°F. This gives you a generous window of about 15-20 minutes to reach the ideal doneness of 130-135°F before the steak becomes overdone. Conversely, cooking the same steak at 400°F will bring it to 125°F in just 15-20 minutes, but you only have a narrow 2-3 minute window before it overshoots the ideal doneness and becomes overdone .

We think a similar dynamic could be happening with hash in your freeze dryer.

As you lower the shelf temperature, you may have a larger sweet spot to pull your hash out before it becomes over-dried. For example, at 40°F, you might reach the ideal dryness in 19 hours and 20 minutes, with only a 1-hour window before it becomes over-dried. On the other hand, at 25°F, you might reach the ideal dryness in 21 hours and 20 minutes, but with a 2-hour window to pull it out before it becomes over-dried.

With this in mind, you might be able to achieve the same quality levels across multiple shelf temperatures, as long as you are drying for the correct amount of time. In our testing, ideal dryness was achieved earlier on the 40°F sample compared to the 25°F sample.

It’s important to acknowledge that other factors are at play. Extra-long batches associated with low shelf temperatures can cause unnecessary wear on your condenser and other components. However, understanding the “optimal dryness window” at different shelf temperatures can help you fine-tune your process to achieve the best possible quality while minimizing wear on your equipment.

Start of an Ongoing Investigation

This first experiment was the beginning of a larger analysis that we’ll be doing in collaboration with more of our customers.

We’re planning a comprehensive study that involves multiple states, a diverse range of batch conditions and starting material to better understand the interplay between shelf temps, hash quality, and dry times.

Our goal is not to identify generic optimal settings, but instead to understand the interplay between these variables so our users can make informed decisions at their own accord. Understanding the relationship is the valuable part, and it makes it easier for you to apply that knowledge across a wide range of batches and user conditions. The focus is on heuristics.


© 2024 CSKD, LLC. All rights reserved.

© 2024 CSKD, LLC. All rights reserved.