DIY Wine Fridge Dryer share your version

[Taproot]

Here’s some example of the beads.

https://www.heartfeltindustries.com/products.asp?cat=65%25+Rh+Humidity+Beads

These guys have them at 60-70% for medicinal herbs.

Medicinal Herbs Humidification

Like I was saying dehydrate them and then in theory they should suck moisture out of the air to refill themselves but also release what they capture to help maintain RH throughout.

Boveda is also big in the cigar world, I use them for cigars and to store weed. They have a lot of RH% levels but 58 and 62 percent are ones commonly used in weed storage.

https://www.amazon.com/s?k=bovdea+58+62&ref=nb_sb_noss

[grow]

I don’t, but the sour crack I’m running now will likely get dried in the fridge so I’ll try to remember to throw my temp/humidity sensor in there to log the progress. Inside the fridge is very simple without the dehu: fan pointed across the cold plate, with variable speed depending on how dry the buds are getting, and the tub of damp rid. Outside is the temp controller that the fridge plugs into.

This is just me thinking out loud, but what about modifying the cold plate to have higher mass and surface area? Like attaching a few heat sinks to the surface so they would also get cold and sap additional moisture from the air inside. I don’t have a good sense for how that would affect the whole system but it seems like the cold plate gets plenty cold enough to cool down a little more metal, and the extra surface area could really help collect more moisture. They might need to be slanted though to help guide the water back onto the plate and into the collection tray. Gonna stew on that one lol

[BTYGMO]

Could you just take the back half of the striped down dehumidifier. Put the metal fins touching the cold plate and water will drip to fridge collection and drain ( if I followed your intent ) maybe something similar but bigger for surface area ? I’ll be interested to follow along. Here is current blueberry muffins graph. Cheers !!!

[Taproot]

Found this on reddit searching for information regarding AVPD and there’s a guy on there that states to be a commerical grower that uses VPD for growing and drying. He does a great job of breaking it down, thought you guys might like to read his comments. “Conor__K” is the user name so you can search for that and filter out the rest if you want.

I can see how just using RH and Temp can be successful for sure and simple. But I can also see why cannatrol uses VPD, it appears to be a more scientific and reliable way to either dehumidify or humidify something with finer control.

https://www.reddit.com/r/microgrowery/comments/snpf4j/drying_by_vpd_temp_and_rh_combinations_to/

These people use VPD for keeping the air in a grow room dry.

Why Vapor Pressure Deficit is Better Than Relative Humidity - DryGair

[grow]

As far as I can tell, Cannatrol ‘uses dew point’ as a workaround to peltiers being ineffecient at dehumidifying at typical 60F drying and curing temps. It’s basically just minimally cooling the condensing plate to the dew point, which allows the chamber to stay cool at 68F without overly cooling, which makes it difficult to affect condensation with the peltier. That company offers commercial grade solutions that use compressors, and not surprisingly, those systems operate at lower temperatures because they’re not limited by the inefficiencies of peltiers.

I think the goal is ultimately to keep the chamber air at the target, while also keeping a condensing surface slightly below the dew point to affect moisture removal. edit: I wanted to add too - it seems like cannatrols have some sort of baffle around their cold exchanger, which not only helps move humid air over the condenser fins, but also helps direct air and circulation all over the chamber itself.

[douggyfresh420]

I know its only been a bit over a week, but im out of weed and couldn’t wait anymore to try this cooler dried bud, so im rolling a doob up for a sneak peak. I gotta say the terps were pretty mild before i ground the bud up, but after i did, i got an explosion of aroma. Obviously this wedding cake needs a good cure on her, but im pretty impressed so far. The buds feel about dry enough id feel comfortable moving them to grove bags. Only issue im seeing so far with the cooler is my inkbird is reading low 70’s rh% and my mini hygrometers are showing mid to low 60’s rh%.

[BTYGMO]

@douggyfresh420 That looks killer !!! I always have differences between the Ink Bird probe and other RH monitor equipment. I’m not sure if they’re just slight variations of RH in the unit or if the probes or meters have a degree of disparity as they are different manufacturers ect. I have noticed at times they are the same and other times they have a variance. Cheers !!!

[Taproot]

Then AVPD should work since Dew Point is directly related. The following is its literal definition.

Atmospheric vapor pressure deficit (VPD) is the difference between the amount of moisture in the air and the amount of moisture the air can hold when it's saturated. It's a measure of how dry or humid the air is, and is also known as the "drying power" of air.

“Dew point temp” is related and should influence over all atmospheric temperature right?

Here’s what I got when asked about temp and dew point.

Dew point temperature is not dependent on temperature, but it is dependent on pressure and water content: 

Pressure: The higher the pressure, the lower the dew point temperature. 

Water content: The more moisture the air contains, the higher its dew point. 

How Heat Index, Dew Point and Wet-Bulb Temperature Describe ...
Dew point is the temperature at which air becomes saturated with water vapor and water begins to condense out of the air. When the air is cooled below its dew point, the water vapor condenses into liquid water, or dew.

Since our primary objective is to remove water content wouldn’t VPD be more desirable since it’s directly related to water content?

I’d assume atmospheric temp would be somewhat relative to dew point temp kinda how RH is relative.

Or goal would be to find and maintain VPD so the “difference” is great enough that the air is not saturated and can still pull out moisture but not so fast that it dries our product out too fast. I’d assume you could start at a high VPD and adjust down kinda like people do with RH%.

Just to note, I’m not trying to start shit with VPD vs RH…just wanted to converse about something interesting.

We have EE and firmware engineers that might be able to help us come up with a plug and play controller or perhaps maybe we could get AC infinity to expand their offerings. I like the 69 pro with it’s wifi monitoring and app to program and adjust it. That’s what we need but I could see us using more programming capability and algos where we can design and run a specific function or aka program and can trigger sub routines…such as ramping up or down vpd automatically. Maybe they’d be interested in producing something like this and call it a 420 pro.

The end result should be to just buy a cheap fridge and plug it into a external controller and have a good dehumidifier (dryer) that’s reliable, predicable and trustworthy.

[grow]

I’m definitely out of my depth on the nuance of all the different parameters, but it does seem like RH and VPD are two sides of the same coin. I’m trying to think in terms of how you use the environmental and calculated data to create set points for your hardware. With the dew point it’s pretty straight forward that you want the condenser plate at least as cold as the current dew point… so you slap a thermometer on the cold plate and run the cooling whenever the temperature rises above the current calculated dew point. This makes it so that as moisture is removed, the RH will naturally start to drop, and the plate will run colder until the target is reached. I guess calculating the VPD could let you dial in how aggressively you want to dry the air, assuming a colder plate removes more moisture? Like you said, go for a higher VPD earlier in the cycle then scale it back as the dry nears completion.

A conversion kit with controller for a mini fridge would be dope.

[Taproot]

RH% is just a relative measurement but it’s correlated to VPD for sure which is why it works. VPD is just much more precise because it measures the current water content and what the water content could be in the air. In our case we’d want a higher deficit so the surrounding air has a higher holding capacity and thus the affinity to attract water molecules or pull them out of something is stronger. I see it as the air is a magnet and we turn up or down the strength to pull out the water it’s attracted to based on how fast or slow we want to dry. VPD is also independent of air temp which RH is relative to for producing a measurement. Here’s what chat GPT stated between the two specific to drying.

ChatGPT…

Relative humidity (RH) and atmospheric vapor pressure deficit (VPD) are both measures of moisture in the air, but they provide different perspectives on atmospheric moisture and have different implications for drying processes.

Relative Humidity (RH)

Definition: Relative humidity is the ratio of the current amount of water vapor in the air to the maximum amount of water vapor the air can hold at a given temperature, expressed as a percentage.

Formula: RH=(ees)×100%RH = \left( \frac{e}{e_s} \right) \times 100%RH=(es​e​)×100% Where:

• eee is the actual vapor pressure.
• ese_ses​ is the saturation vapor pressure at the same temperature.

Implications for Drying:

• High RH: When relative humidity is high, the air is already holding a significant amount of water vapor. This means there is less capacity for the air to take on additional moisture from surfaces, resulting in slower drying rates.
• Low RH: When relative humidity is low, the air has a greater capacity to absorb more water vapor. This leads to faster drying rates as the moisture from surfaces can readily evaporate into the air.

Atmospheric Vapor Pressure Deficit (VPD)

Definition: Vapor pressure deficit is the difference between the saturation vapor pressure (the maximum amount of water vapor the air can hold at a given temperature) and the actual vapor pressure. It represents the drying potential of the air.

Formula: VPD=es−eVPD = e_s - eVPD=es​−e Where:

• ese_ses​ is the saturation vapor pressure at a given temperature.
• eee is the actual vapor pressure.

Implications for Drying:

• High VPD: A high vapor pressure deficit indicates a large difference between the air’s capacity to hold water vapor and the actual amount of water vapor present. This means the air has a high drying potential and can absorb moisture rapidly from surfaces, leading to faster drying.
• Low VPD: A low vapor pressure deficit means the air is closer to its saturation point and has less capacity to absorb additional moisture, resulting in slower drying rates.

Key Differences and Applications

1. Measurement Perspective:

• RH measures the current state of humidity relative to saturation.
• VPD measures the potential or capacity of the air to absorb more moisture.

2. Sensitivity to Temperature:

• RH is highly sensitive to temperature changes because the saturation vapor pressure increases exponentially with temperature. As the temperature rises, the same amount of water vapor results in a lower RH.
• VPD provides a more direct measure of drying potential because it explicitly accounts for the difference between the current and maximum possible water vapor pressure, making it a more stable indicator under varying temperatures.

3. Drying Effects:

• RH gives a relative sense of how “humid” the air feels but doesn’t directly indicate the drying capacity. For example, a high RH at a high temperature might still result in a significant drying potential because the saturation vapor pressure is very high.
• VPD is a direct measure of drying potential. High VPD always means higher drying potential regardless of the absolute humidity or temperature.

Practical Applications:

• Agriculture: VPD is crucial in agriculture for understanding plant transpiration and irrigation needs. High VPD can lead to higher water loss in plants, necessitating more irrigation.
• Drying Processes: In industrial and food drying processes, VPD is a more useful measure than RH because it directly indicates how quickly moisture will evaporate.
• Weather and Comfort: RH is often used in weather reports and HVAC systems to indicate comfort levels, as it correlates with how the air feels to humans.

Understanding both relative humidity and vapor pressure deficit helps in various fields to manage moisture levels effectively and optimize processes involving drying and moisture control.

[BTYGMO]

@Taproot @grow You guys are champions for the cause !!! Your contribution’s have been incredibly insightful. I am going to be considering some changes before the next fresh run thru the dryer. Another thought as am noticing the trends on this blueberry is drying slightly faster (less dense nugs) than say a denser bud. I was considering a sponge as the was the Canatroll solution. But I have not really noticed the need in the graph but a physical test showed these are drying faster. Should I try a sponge on less dense nugs or drop In my case RH slower. Maybe consider dropping .5 RH per day in the beginning? Cheers !!!

[Taproot]

If you need moisture added I’d suggest using a two way humidity device like I posted above that way they add just what is needed per your desired levels and no more.

I will say that the Boveda packs I use tend to punch a litter higher than the RH% printed on their pack when in a “Sealed” container like my plastic coolidore or glass jar. So, for example my 62% pack will generally regulate the RH between 62 and 64% and the manufacture says the film they use adjust to the ambient temp. They’d behave a little different in a wood humidor. Next time I buy some I’ll get the 58% since they will most likely ride abound 60% for me.

[Taproot]

For those interested… I asked ChatGPT on creating a strategic detailed plan on using VPD for drying cannabis in the fridge. Interesting how it starts off with a lower VPD and ramps up to a higher VPD for faster drying. It’s the inverse of what we’ve been discussing of starting high and going low. Anyways…

ChatGPT …
Drying cannabis in a fridge requires a controlled environment to preserve the cannabinoids and terpenes while preventing mold and mildew. Utilizing Vapor Pressure Deficit (VPD) as a guide can help optimize the drying process by managing the air’s drying potential effectively. Here’s a strategic and detailed process for using VPD to dry cannabis in a fridge:

Initial Setup

1. Fridge Preparation:

• Ensure the fridge is clean and sanitized.
• Set the fridge to a temperature range of 55-60°F (13-16°C).
• Install a hygrometer and thermometer to monitor relative humidity and temperature.
• Use a small fan for air circulation, ensuring it doesn’t blow directly on the cannabis.

2. Harvesting:

• Harvest the cannabis plants by cutting the branches and removing large fan leaves.
• Hang the branches or place the buds on drying racks inside the fridge.

Drying Process Using VPD

Phase 1: Initial Drying (Day 1-3)

• Objective: Reduce the initial moisture content without causing rapid evaporation, which can degrade cannabinoids and terpenes.
• Temperature: 55-60°F (13-16°C)
• Relative Humidity (RH): 60-65%
• Target VPD: 0.3-0.6 kPa
• Steps:
  • Maintain a low VPD to prevent the outer layer of the buds from drying too quickly.
  • Monitor the conditions closely and ensure air circulation is adequate to avoid mold.

Phase 2: Intermediate Drying (Day 4-7)

• Objective: Continue moisture reduction while preventing over-drying.
• Temperature: 55-60°F (13-16°C)
• Relative Humidity (RH): 55-60%
• Target VPD: 0.6-0.9 kPa
• Steps:
  • Gradually increase VPD to allow for steady moisture removal from the inner parts of the buds.
  • Adjust the fridge settings if necessary to maintain the desired RH and temperature.

Phase 3: Final Drying (Day 8-14)

• Objective: Reach the optimal moisture content for curing without losing potency or flavor.
• Temperature: 55-60°F (13-16°C)
• Relative Humidity (RH): 50-55%
• Target VPD: 0.9-1.2 kPa
• Steps:
  • Aim for a higher VPD to ensure the buds are sufficiently dry for curing.
  • Check the buds daily by gently squeezing them; they should feel dry on the outside but still slightly spongy on the inside.

Transition to Curing

• Once the buds are dry to the touch and the stems snap rather than bend, they are ready for curing.
• Place the buds in airtight glass jars, filling them about 75% full to leave some air space.
• Store the jars in a cool, dark place, opening them daily for the first week to release moisture (burping) and then less frequently afterward.

Monitoring and Adjustments

• Daily Checks: Regularly check the temperature, RH, and VPD inside the fridge to ensure they remain within the desired ranges.
• Adjusting RH: If RH is too high, use a dehumidifier or silica gel packets. If too low, add a humidifier or a small dish of water.
• Air Circulation: Ensure continuous but gentle air circulation to prevent mold and mildew without over-drying the buds.

Final Notes

• Patience: The entire drying process can take up to two weeks, depending on the initial moisture content and the consistency of the fridge conditions.
• Consistency: Maintain consistent environmental conditions to ensure the highest quality of dried cannabis.

By following these phases and monitoring VPD closely, you can achieve an optimal drying process that preserves the quality and potency of your cannabis while preventing issues like mold and over-drying.

For giggles I wanted to just ask it about storing cannabis based on VPD.

Storing cannabis effectively involves maintaining an environment that preserves its potency, flavor, and aroma while preventing degradation and mold growth. Using Vapor Pressure Deficit (VPD) to guide the storage conditions can help achieve this balance by controlling the moisture content within the storage environment. Here’s a strategic and detailed process for using VPD to store cannabis:

Initial Setup for Storage

1. Storage Environment:

• Choose an airtight container (e.g., glass jars with airtight lids).
• Store containers in a cool, dark place to avoid exposure to light and temperature fluctuations.
• Equip the storage area with a hygrometer to monitor relative humidity (RH).

2. Initial Drying:

• Ensure cannabis is properly dried before storage. Ideally, the buds should have a moisture content of around 10-12%, which translates to stems that snap rather than bend.

Storing Process Using VPD

Optimal Storage Conditions:

• Temperature: 60-70°F (15-21°C)
• Relative Humidity (RH): 55-62%
• Target VPD: 0.8-1.2 kPa

Detailed Steps for Using VPD in Storage

Phase 1: Initial Storage Setup

• Objective: Establish and maintain optimal storage conditions to prevent degradation and mold growth.
• Temperature: 60-70°F (15-21°C)
• Relative Humidity (RH): 55-62%
• Target VPD: 0.8-1.2 kPaSteps:
  • Airtight Containers: Place dried cannabis buds in airtight glass jars or containers. Fill them about 75% full to allow some air circulation within the container.
  • Monitoring RH: Use a hygrometer within the storage area or inside the jars (e.g., small digital hygrometers) to monitor RH levels.
  • Adjusting RH: If RH is below 55%, consider adding Boveda humidity packs (58% or 62%) to the jars to maintain optimal RH. If RH is above 62%, dry the buds slightly more before storing them again.
  • Temperature Control: Keep the storage area at a stable temperature between 60-70°F (15-21°C) to prevent cannabinoid degradation.

Phase 2: Short-term Storage (First 2-4 Weeks)

• Objective: Ensure cannabis stabilizes and maintains its quality during the initial storage period.
• Temperature: 60-70°F (15-21°C)
• Relative Humidity (RH): 55-62%
• Target VPD: 0.8-1.2 kPaSteps:
  • Regular Monitoring: Check the RH and temperature inside the jars daily for the first week, then reduce checks to once a week.
  • Burping Jars: Open the jars for a few minutes daily during the first week to release any excess moisture (burping). This helps maintain proper RH and prevents mold growth.
  • Adjusting Conditions: If RH fluctuates significantly, adjust the environment using humidity packs or by drying buds slightly if too moist.

Phase 3: Long-term Storage (Beyond 1 Month)

• Objective: Maintain optimal storage conditions to preserve cannabis quality over an extended period.
• Temperature: 60-70°F (15-21°C)
• Relative Humidity (RH): 55-62%
• Target VPD: 0.8-1.2 kPaSteps:
  • Infrequent Checks: Check the RH and temperature monthly to ensure conditions remain stable.
  • Humidity Packs: Replace humidity packs as needed to maintain the desired RH levels.
  • Avoiding Light: Ensure jars are stored in a dark place to prevent light degradation of cannabinoids and terpenes.
  • Stable Environment: Avoid frequent opening of the jars to minimize fluctuations in RH and temperature.

Monitoring and Adjustments

• Consistent Monitoring: Even after the initial stabilization period, periodically check the storage conditions to ensure they remain within the optimal range.
• Environment Control: If you live in a region with significant seasonal humidity changes, consider using a dehumidifier or humidifier in the storage area to maintain consistent conditions.

Final Notes

• Avoiding Mold: Maintaining RH below 62% is crucial to prevent mold growth. If you notice any signs of mold, remove the affected buds immediately and re-evaluate your storage conditions.
• Long-term Preservation: Properly stored cannabis can retain its quality for up to a year or more. Beyond this period, cannabinoids and terpenes may degrade, affecting the potency and flavor.

By following these phases and monitoring VPD closely, you can ensure your cannabis remains fresh, potent, and free from mold during storage. This strategic approach helps preserve the quality of your cannabis, providing an optimal experience even after extended storage periods.

[BTYGMO]

@Taproot very cool !!! I hope Chat GPT is accurate lol. Just the way things trend with my set up and chosen parameters my current dry cycle trends are close to those numbers lol. My intention as always is to stretch drying out for 2 to 3 weeks Cheers !!!

[Gpaw]

Yes, what it’s saying makes sense.
I’d quibble on some of the RH numbers but definitely within instrumentation error…
{nerd joke}

Any idea where it’s looking for the information?

Cheers
G

[Taproot]

Just for grins I still had the session opened and asked it.

ME: where did you obtain this information, can you provide the sources

ChatGPT

The information provided about using Vapor Pressure Deficit (VPD) for drying and storing cannabis is based on general principles of plant drying, VPD management, and best practices commonly recommended within the cannabis cultivation community. Here’s a breakdown of where these principles come from.

End

I cut the rest as it was too much. It then provided a comprehensive list of sources such as peer review papers, websites and books etc.

[Gpaw]

The tl:dr is:
“Not telling”

Cheers
G

[Taproot]

Go check it out, you can get a free account. There’s a limit on how many questions you can ask for a free account per day. It’s pretty comprehensive. Be very specific on what you ask…it’s all about how you present your question.

I had it write me a few bash scripts for monitoring a vpn connection and other various linux stuff I needed to do and it did a very good job but along the way I had to refine my question to get the script I needed. The cool part is it would modify the script which shows some sort of remembering what it was working on.

[CWF]

I’m about to try my first cycle in the Kt WC20 unit I’ve been tinkering with for a few weeks. I’ll keep a log of the temp/rh and see how it goes, I guess. I’ll be trying it for real after learning what I can…

If I may ramble on the math, which is well-documented, it holds no mysteries - both VPD and dew point temperature contain the same data to compute them : air temp and RH, so, there’s no magic here - either one, VPD or DP, will do the job as a control variable equally well.

Also pointing out the obvious - when a bud is cut, transpiration ceases, so there’s no leaf temp difference - air and cut bud are same temp in the cooler, right? So if using ACI controller or other to see “drying” VPD, set leaf differential or offset to 0.

[CWF]

Update: packed to da max, minimal hang time wet, Kt set to 60F. RH hit 80-78% avg first day. Set RH CTL to 78-76 (on-off). I did get some icing up of the dehmi to start, but that has seemed to stop after a day or two.
3rd day: running 74-72 RH (on-off), and avg RH has dropped to around 76 avg. Lots of water on floor pan under unit, which is on a milk crate with stock (dinky) pan removed, slight tilt toward the rear for good drainage. I’ll probably start stepping it down a bit each day tomorrow.