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relative humidity and drying..., or hydrating for that matter

aGAKWq

Well-known member
Sales
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#1
So, I've read about hydrating dry tobacco. Let's say it's a cloudy rainy day and the relative humidity (RH) is in the 80s or 90s. Wouldn't just leaving some out achieve hydration similar to covering with a napkin and wetting it?

How about drying. If the RH is high, wouldn't the tobacco be dryer (driest lol) if you just smoked it instead of leaving it out? Or, wait for a low RH drier day and then air it out.

:popc:

:puffy:
 

JustScott

Well-known member
#2
Well, I can speak from my experience to say that 80+ RH, even at 60 degrees, will rehydrate tobacco. Even from just opening a jar and loading a pipe multiple times, the super-humid air exchange will wet it. I mean, it's not going to make it sopping wet or anything, but if you LIKE your tobacco DRY, you will definitely notice. If I were trying to rehydrate, though, I would still go with the wet napkin method, because it's going to take care of the situation faster.
On the drying question, absolutely. That's my usual way, get out enough to fill the pipe, fill the pipe, get any extra tobacco back into the jar ASAP (because otherwise, I'll have to wait possibly months for a day dry enough to get it back to where I like it.) I try to get my jars dry enough to smoke well for me, and then I try even harder to KEEP them that way.
 

aGAKWq

Well-known member
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#3
Thanks Scott. It's nice to bounce ideas off someone to get a feel for things. After I dry most times, I have extra that I keep in a baggie, and that stuff goes in the bottom of the next bowl.

:puffy:

Oh and I brought my digital thermometer downstairs, which I keep upstairs - mostly so during the summer I can see if the a / c is still working lol. Anyway, the airport temp ( my weather bookmark ) was saying - say 89 percent humidity (RH), and my digital said 27 percent in the kitchen. So there's that.
 
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JustScott

Well-known member
#4
Oh and I brought my digital thermometer downstairs, which I keep upstairs - mostly so during the summer I can see if the a / c is still working lol. Anyway, the airport temp ( my weather bookmark ) was saying - say 89 percent humidity (RH), and my digital said 27 percent in the kitchen. So there's that.
Yeah, with a/c you have a nice, dry interior of the house. In SF, pretty much none of the older houses have central heat/air systems, so my indoor RH is at least what it is outdoors, sometimes slightly higher. I was celebrating yesterday, the RH was in the low 50s so I could dry my Irish Flake with only the help of a light breeze (instead of a warm appliance.)
 

soutso

Well-known member
#6
Other than RH, another thing you must consider when discussing or thinking about water and tobacco is ..... temperature.

You mention a rainy day with 80-90RH wetting your tobacco, well you probably will, but not if its 95F (this is just a guess)

To keep it simple, tobacco is more likely to dry in warmer temps and get wetter in cooler temps. I have a good example that illustrates this that occurred in the last week. I received a tin of Solani Silver Flake (my God this stuff is glorious, get it). It was a 100g tin, it came wrapped in clear plastic which is obviously inside the tin. We have had a very hot summer here in Sydney and I received it on a day when temps were in excess of 95F. (and I assume a lot more in the delivery drivers van) The package itself was literally warm to touch.

After unwrapping the package, I opened the tin and there were tiny beads of water in the plastic folds that had the tobacco in it. I placed it on my dining table in a cool air conditioned room and after checking it a few hours later, I noticed that the water had disappeared. Tobacco is a hygroscopic material, ie like a sponge. The water in the air is attracted to it. When temperatures increases, the water escapes from the tobacco and when temperature decreases the water in the air absorbs into the tobacco.

Test what I say with a sponge, you'll see what I'm saying. Cheers.
 

5star

PSF transfer
Patron
#7
I recently received some 10 year old McClelland baccy from a good friend. It was sealed in a vacuum bag. There was one big chunk that was hard as a brick. The loose tobacco was crunchy dry. I put it all in a mason jar with a 62RH Boveda pack (60gm size). In a month the moisture level was perfect. I removed the Boveda. The baccy is absolutely delicious.

BTW - this shows me quite convincingly that regular vacuum bags won't do the job for longer term storage. I plan to get some Mylar bags to try out (mainly for cigar use).
 

WalkinStick

Driving the Bandwagon
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Old Ted Award Winner
#8
80-90RH wetting your tobacco, well you probably will, but not if its 95F (this is just a guess)
It will, actually. It’s regularly 90-95RH here and gets into the low 100’s F in the summer. I have to put tobacco out to dry in front of a fan or pop it in the microwave. I’ve had dry tobacco rehydrate itself just sitting in a ziplock bag.
 

RedScot

Well-known member
#9
It will, actually. It’s regularly 90-95RH here and gets into the low 100’s F in the summer. I have to put tobacco out to dry in front of a fan or pop it in the microwave. I’ve had dry tobacco rehydrate itself just sitting in a ziplock bag.
Relative humidity is relative to the maximum amount of water the air will hold, and temperature plays a huge role. Dew, for example, forms because the air cools and cannot hold as much moisture. Same reason condensation forms on the outside of a glass or bottle of cold stuff.
90% RH @ 95°F is tremendously damper than 90%RH @ 35°F. I can explain this a lot more but that's not the point.
Whether an object humidifies or dehumidifier will depend on only two factors - relative factors. 1) The amount of moisture in the object compared to the amount of moisture in the air, and 2) the temperature of the object compared to the temperature of the air.
Assuming your jar of tobacco is at the same temperature as the ambient air simplifies the situation b/c it eliminates half of our variables...assuming we don't heat the jar by setting it in direct sunlight, of course. Don't do that. At identical temperature, the humidity in the open jar (or tray, or whatever) and its contents will equalize with the ambient air. So if the tobacco is dryer than the surrounding air it will moisten, but if it has more moisture than the ambient air it will dry.
However - however - remember the temperature has an impact, too. So if you jar up on a warm day with 72%RH, the air in the headspace will have more moisture than the air does on a colder day, even if the RH is 72%. If the air inside the jar cools too, then it can't hold as much water as it did on the warmer day, and the excess moisture will condense on the inner walls of the jar and on the tobacco.
Now I think I confused myself.
ETA What needs to happen is not moisture condensed on the tobacco, but moisture absorbed into the tobacco. Outside moisture means mold has a better chance of grabbing hold. Again, however, it will depend on the moisture levels relative to the air surrounding the tobacco. Warm air holds more moisture, again, so trying to dry a bowl of tobacco on a hot humid FL day will be next to impossible if you depend solely on ambient air. A fan increases the evaporation rate some days, but on really humid days the microwave will be the weapon of choice.
If you need to know how microwaves affect water molecules, just lemme know.
 
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RedScot

Well-known member
#13
Doesn't the microwave excite the water bonds? Kinda spins them up, yah?
Yep. Temperature is a vibrational energy, but microwaves increase the spin of water molecules, and the spinning gets 'em to jostling other molecules, incrrasing their vibration.
The US radar installations in Alaska fostered a unique behavior among staioned troops: some would go stand in front of the radar dishes to warm up. They started investigating and found the microwave effect. That's why the first Amana microwave was called the Radarange.
 

highstump

Well-known member
Patron
#14
Yea, all that stuff.
This pretty much sums it for me as well WS.

Here is my take on weather and tobacco. If its cold out I wear a hat and coat, and if its hot the coat stays on the rack but I still wear the hat to keep my head from getting burned in places where my hair just isn't what it used to be.

As things relate to pipe tobacco go, if its a bit damp it goes on a paper plate resting on a lamp shade over a 100 watt bulb. If it seems a bit dry I load a bowl, take a deep breath and exhale through the bowl. Works every time.