Risks of humidified or heated storage
As a result of my storage experiment posts, especially the one detailing the Hotbox storage system, I’ve received a lot of emails and seen some commentary (good and not so good) about it. There is no shortage of pu-heads with very strong opinions on how you should store your tea, so forgive me for adding to the noise: I’m reporting the results of my tests, and you can draw your own conclusions.
In my opinion, it makes no sense to prescribe a storage system unless you know what you are trying to achieve. What is the goal of storage? I outlined my goals at the start:
- to maintain: pungency, resin, sweetness, energy…
- to reduce: harsh bitterness, greenness, rough astringency,
- to develop: emergent flavour, aroma, deepening energetic effects.
I think that most newcomers to puerh, especially if they are following the strategy of buying newly-made tea and hoping it improves with age, will have goals overlapping with those above. If you have well-aged tea and don’t want it to change, I believe that heated (and certainly humidified) storage is not appropriate.
Equally important, since storage is a long game, is whether your system is sustainable: for me this means
- no maintenance required, e.g. during long absences
- minimize risk of damage, for example by mold, pests, smells, drying
- maintain individuality of teas, no mixing of aromas/tastes
- cheap, energy efficient
Red flags of home storage
The first two points above (no-maintenance and risk of damage) are where most storage solutions go wrong. The following are some of the questions collectors should ask themselves.
- If you leave your storage alone for 6 months, and if the power goes out, will anything bad happen? If so, your storage is risky.
- Is there any chance at all that something could tip over and wet your tea? If so, your storage is very risky.
- Are you keeping your tea near fragrant woods (yes, this includes pine, any new wood, untreated wood etc.)? Near the kitchen? In the garage? Without a seal to keep out smells? Then you need to rethink your storage. Do you vape/smoke/use incense? With tea not sealed away? Again, very risky.
- Do you heat or air condition your living space? Can this air can travel to your tea? Do you live in a very dry atmosphere? Then you are risking drying out your tea.
- Is it possible for bugs to get into your storage? Can bugs get through cardboard, fabric, or bamboo? (Hint: yes they can)
- Is your tea exposed to an active humidity source? If so, what would happen if all the water in that humidity source were released? Would that lead to mold? If so, you are rolling the dice in the long term.
Rationalization of risky choices: True story, bro!
Most collectors are well aware of the red flags listed above. Nevertheless, many somehow find a way to rationalize taking on high levels of risk. Here’s an example of a train of thought I’ve encountered (I have nothing against crock storage, this is just an example):
- I want to use a crock.
- But my apartment is too dry, so I must add humidity; add Boveda packs.
- But the crock is not sealed, so I must add a new Boveda pack each month.
What is potentially wrong with the above? The expense of Boveda packs. The fact that monthly maintenance is not sustainable. The risk of added humidity in an open / uncontrolled system. The fact that smells can get in. The fact that bugs can get in. All of these are unnecessary risks. But the main problem with the above is that we began with an arbitrary choice to use a crock. Perhaps your choice of storage solution should be adapted to your living situation and not the other way around. Here is another example I’ve encountered:
- Puerh tea improves with age: it’s like wine!
- Let’s store it in a wine cave!
- The wine cave has wooden shelves, so we’ll use cardboard boxes to protect the tea.
What is potentially wrong with the above? Perhaps a better question is if there is anything right about it… Wine caves are too cool and too damp, and they have a distinctive musty odor. Cardboard is basically a porous sponge, and offers little protection against smells or mold. The wooden shelves will impart wood taste to the tea. And of course, besides corrupt politicians you can also find bugs in wine caves. In this case, the collector was aware of all these risks, but rationalized using this system because they were enamoured by their pet theory about tea and wine. Perhaps the lesson is: don’t let your pet theory overrule known risk factors.
Main risks of hotbox storage
Over the three years that I’ve been running the hotbox, I’ve identified three issues which people should be aware of.
1. Misunderstanding and Mold
The first issue is not really an issue with the hotbox as I’ve described it here, but a misunderstanding about it. There should be no added humidity to the mylar bags while they are in the hotbox or in long-term storage. Some people seem to think that adding humidity is a minor modification, but it is not. It is very risky to add humidity even if it is a Boveda pack. Boveda packs are slow to react to changes in humidity, and if there is an accumulation of humidity (and if the cake has mold spores, which is often the case), you will get mold. I do use Boveda packs to humidify dry cakes; this is for at most 3 months and I do it at room temperature. Bovedas are not permitted in the hotbox. Here is a moldy example from one of my early tests three years ago with a 69% Boveda pack at 32C:
2. Failure of Mylar bags
The second issue which I had to address on a couple of occasions is the failure of Mylar bags. It is important to use good-quality sturdy Mylar bags for long-term storage. Clear Ziploc bags of any kind are not suitable, they are porous and have notoriously bad seals. But even the best Mylar bags will fail if you manipulate them too many times. If your Mylar bag has a zip closure, the first point of failure is this zip seal (punctures are much less common). Most of my zip bags have survived for 3 years without a zip failure (they continue to maintain the tea’s generated humidity), but some (in my case about 5%) failed and I had to replace them. Some of my bags are heat sealed, and none of these has failed. So, I recommend heat sealing if you are using Mylar. For Mylar zip bags in good condition, however, my tests show they do maintain humidity over multiple years of heated storage. To be clear: if the seal fails, your tea will gradually lose humidity and get too dry.
A better solution, which I find too costly for all my cakes, is to use Onyx stainless steel 23 cm diameter containers (these have a latex seal). These are excellent, and I use them for my more expensive cakes. In fact, for someone with a small collection of only a few cakes, I would strongly recommend using these containers for room temperature storage – they comfortably hold five full-size puerh cakes. These also avoid the “problem” of plastic — if you are concerned about plastic breaking down and somehow entering your tea (I am not, in the case of using Mylar for long-term dry tea storage), you can avoid plastic altogether by using this stainless steel container.
3. Temperature sensor failure
Another problem I encountered (it happened one time in three years) is that the connection between my temperature sensor and my Heat Outlet Thermostat (Inkbird C206) failed. I think this happened because something hit the sensor plug on an angle and bent it out of shape. This didn’t cause any problem for my tea, it just deactivated the heating system. I still think the C206 is a good unit, and it has even come down in price to 20$, but you should be aware that the connection is not robust enough to be handled roughly.