Moldy Pu'erh!!!

Puerh and other heicha
26uk
Posts: 70
Joined: Sat Dec 05, 2020 8:19 pm
Location: Bay Area, Ca

Wed Feb 03, 2021 1:04 am

Rickpatbrown wrote:
Tue Feb 02, 2021 11:43 pm
After a couple of days wringing my hands and revisiting some TeaDB articles and thinking more about the RH/Temp/dew point relationship ... I am fairly certain that the issue was that the temperature was too low at night. Or you can also say that the RH was too high for those temperatures. I'm really lucky that my main stash didnt get hit.

I'm going to look into setting up a thermostat or and arduino based system (depending on how many hours I want to devote) that can regulate the temperature around 75-80°F and keep RH at 68%.

I guess this has been. Good learning experience for me, with minimal loss.

I'm going to hose down the moldy pumidor with ethanol and see if I can recommission it for my pathetic shou supply.
I would just do RH 65%. I would be more risk averse based on your situation. But up to you.
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Iizuki
Posts: 78
Joined: Wed Feb 12, 2020 12:23 am

Wed Feb 03, 2021 6:23 am

26uk wrote:
Wed Feb 03, 2021 1:02 am
When temperature drops, the air cannot hold as much water vapor. So even with the same amount of vapor, the RH is higher. RH is the absolute amount of water vapor divided by total water vapor the air can hold. So temp drop is the denominator decreasing. RH can change when numerator or denominator changes.
This I do understand.
26uk wrote:
Wed Feb 03, 2021 1:02 am
When RH is high, the material (say tea leaves) will absorb more water.
This is what puzzles me. I'm not saying it's not true. I'd just like to understand why it is so. The partial pressure of water vapor does not increase when temperature drops, right? If it did, it would be pretty intuitive.
faj
Posts: 710
Joined: Mon Oct 14, 2019 6:45 am
Location: Quebec

Wed Feb 03, 2021 6:26 am

Rickpatbrown wrote:
Tue Feb 02, 2021 11:43 pm
I'm going to look into setting up a thermostat or and arduino based system (depending on how many hours I want to devote) that can regulate the temperature around 75-80°F and keep RH at 68%.
I really am no expert about tea storage and how sensitive tea is to mold at various conditions, but dpcalc.org, if you trust that tool, states that 75F at 68% RH or above is at risk for mold. Same for 80F actually. Maybe in practice mold only forms if you stray quite a bit above the RH threshold they suggest, but this calculator does seem to imply that, at typical room temperatures, the RH usually associated with tea aging will never keep you safely away from the risk zone.

Ventilation reduces the chance that drops in temperature will cause RH to spike, but makes RH control problematic. Insulation may help reduce temperature swings, and therefore RH swings. In the end, reducing the risk of mold might mean compromising on the speed of aging, I guess...
faj
Posts: 710
Joined: Mon Oct 14, 2019 6:45 am
Location: Quebec

Wed Feb 03, 2021 6:34 am

Iizuki wrote:
Wed Feb 03, 2021 6:23 am
This is what puzzles me. I'm not saying it's not true. I'd just like to understand why it is so. The partial pressure of water vapor does not increase when temperature drops, right? If it did, it would be pretty intuitive.
Start from the idea that RH represents how thirsty air is. Low RH = air very thirsty. High RH = air not thirsty. Air will absorb water more quickly the lower RH is. This works both ways : if you want to remove water from air, you have to work harder when RH is lower.

Mold needs water. In a sense, mold is in a fight with air for water. In this fight for water, what counts is not how much water vapor is in the air in the absolute, but how much air will fight to keep its water when mold tries to remove it (and then keep it).
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wave_code
Posts: 575
Joined: Wed Nov 21, 2018 2:10 pm
Location: Germany

Wed Feb 03, 2021 6:54 am

right now I've got 65% boveda packs, and some small isolated experiments at 68% for now trying to rehydrate some kunming tea, but I'm thinking of going down to 60 just to be safe across the board. weather here is usually pretty stable and in winter my living room is rather cool, but in summer temps can fluctuate a bit more and I'm a little worried, especially since I have things in plastic containers. I'd maybe worry a bit less with clay, but clay storage for liu bao is a bit more difficult than pu, and the lack of compression makes me a bit concerned too. I can understand with sheng theres more motivation to push the aging along with higher temps/RH and buying older tea gets $$ really fast. I also like having some more humid storage character, but I feel like maybe the safer bet is to get something that has spent a year or couple years in HK or Taiwan and then let it go slow from there and just be patient than trying to push things for years at a time in home storage.
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