Relative vs Absolute Humidity

[Wolfpack]

I have a science question, which may have been covered before. I have been storing my Cuban Cigars at 65RH / 21C, and my Dominican Cigars at 69RH / 21C.

I recently bought a cigar cooler / humidor which maintains a temperature around 18C. Since RH is relative to temperature, I think that i should pay attention to Absolute Humidity, which would then require me to raise the humidity somewhat on both type of cigars in order to keep the moisture content consistent at the lower temperature.

My though is to keep the Cuban Cigars at 69RH / 18C, and the Dominican Cigars at 72RH / 18C. That would keep the Absolute Humidity for both cigars about the same as if I were still keeping them at 21C.

Any thoughts... But i would think if we are concerned about water content in the actual cigar, and cold air holds less water, we thereby need to raise the RH as the air gets colder to keep the cigar's actual humidity consistent.

Thanks in advance for your help.

[Fugu]

Yes - this has been covered (many times) before. And no - don't make this mistake and adjust for absolute humidity! (you are certainly not the first to think that way)

What is crucial for tobacco equilibrium moisture is relative humidity in the storage atmosphere. For a simplification, keep that constant, irrespective of temperature, whether storage at 18 or 21 °C. But - caveat: there is a slight tradeoff between equilibrium tobacco moisture and storage rH with temperature. The colder it gets, the moister (!) will get your cigars, meaning you'd have to slightly compensate for that by keeping rH a little lower for colder storage. Paradoxically, you might think, although the absolute water content in the atmosphere will be lower. But that's a thermodynamic effect of water adsorption and desorption processes to the solid phase. Over to @PigFish for the finer details and numbers ...

[TheGipper]

Oft debated, never settled.

The fundamental question I never see addressed in these threads is at the root of the real answer:

Does tobacco's ability to retain moisture vary by temperature in exactly the same way as air?

If the answer is yes (or the difference is insignificant), then RH alone should suffice and we should target the same RH at all temperatures.

If the answer is no, then we would have to adjust.  And presumably tobacco can hold more moisture at below room temperatures, so we would adjust RH higher for low temps, and lower RH for high temps.  (By how much is another question.)

Personally, I suspect the answer is technically no, but that the delta for 70 degrees F vs 65 degrees F is not large enough to get worked up over.  But I suspect if you were to long-term store cigars at 50F and 65%-70% RH, you're going to have dead cigars on your hands down the road.  And a logical extension of this is that there are temperatures below which not even 99% RH will maintain the proper condition of cigars.

[PigFish]

50 minutes ago, TheGipper said:

Oft debated, never settled.

The fundamental question I never see addressed in these threads is at the root of the real answer:

Does tobacco's ability to retain moisture vary by temperature in exactly the same way as air?

If the answer is yes (or the difference is insignificant), then RH alone should suffice and we should target the same RH at all temperatures.

If the answer is no, then we would have to adjust.  And presumably tobacco can hold more moisture at below room temperatures, so we would adjust RH higher for low temps, and lower RH for high temps.  (By how much is another question.)

Personally, I suspect the answer is technically no, but that the delta for 70 degrees F vs 65 degrees F is not large enough to get worked up over.  But I suspect if you were to long-term store cigars at 50F and 65%-70% RH, you're going to have dead cigars on your hands down the road.

Frankly I am exhausted with rH questions... -LOL Yes, I actually said that.

The discussion has been long since settled, just not with smokers, largely due to the bad data on the net.

Tobacco is not at all like water vapor in space. Tobacco is more like a pool of water (liquid) below water vapor gas in space. Tobacco then is more like liquid water, water bonded to water, than free water vapor in space, water not bonded to anything.

Air, technically does not retain water. Space can 'contain' water vapor.

 

[Fugu]

16 hours ago, TheGipper said:

Oft debated, never settled.

Often debated perhaps but your fundamental question has been settled. Pure physics.

The answer to the question formulated is no as you suspect. That is very simply understood because: The ability of a material (or material mix) to hold (adsorb) water is a material specific constant, the so called hygroscopicity. Since this is material-dependent (see boveda packs as a quite tangible example), but the physical function of the saturation concentration of the gas H2O in respoinse to temperature (and pressure and gas composition. Which is often neglected, since we are usually dealing with constant conditions in that respect), is not --> the answer must be no.

In which particular direction and extent this function deviates from the pure gas behaviour is a matter of experimental investigation.

[ayepatz]

I understand none of this. I still like cigars.

[TheGipper]

2 minutes ago, Fugu said:

Often debated perhaps but your fundamental question has been settled. Pure physics.

Sure, I accept there is a settled scientific answer.  Just not to the satisfaction of cigar forum denizens, which is the context I'm using.    Plus all of these threads struggle to identify actual published hard data on how tobacco responds to the relatively small temperature variations encountered in typical household situations.

Perhaps interesting as a thought experiment is to consider a box of cigars stored in the antarctic, at the outside temperature but inside a box maintaining 70% RH.  Many threads like this have people who tell us that as long as 70% RH is maintained, those cigars would be fine.  But 70% RH at those temperatures is a vanishingly small amount of moisture, which would quickly render those cigars completely expired.

Anyway, ya'll should move to Oregon where it's easy to keep a house at a steady temperature all year round, without huge humidity variations.  It's easy keeping humidor conditions stable here.

[Fugu]

Same here, I am blessed with the advantages as well as disadvantages of the temperate regions, too... 

[PigFish]

If it is not settled with cigar smokers, it is because they are people steeped in myth and groupthink. Sorry, but that is the truth about us as a group. (MHO)

-Piggy

[PigFish]

1 hour ago, ayepatz said:

I understand none of this. I still like cigars.

I like this... but frankly, I am not really understanding cigars anymore!!!

-Piggy

[PigFish]

57 minutes ago, Fugu said:

Same here, I am blessed with the advantages as well as disadvantages of the temperate regions, too... 

My environment sucks... I have to make one that works. Yesterday it was 100F here. That sucked too! I am beginning to believe in global... global.. I just cannot say it!!! 

-Piggy

[Wolfpack]

11 hours ago, PigFish said:

My environment sucks... I have to make one that works. Yesterday it was 100F here. That sucked too! I am beginning to believe in global... global.. I just cannot say it!!! 

-Piggy

Your telling me. check out tropical cyclone #18:

http://www.nhc.noaa.gov/refresh/graphics_at3+shtml/114533.shtml?tswind120#contents

header my way, again this year (that's the 3rd one). Interesting - they really shouldn't move NE when they are in the Gulf - but NOW they do.

[garbandz]

A Jedi level thread.

(well, the first bit)      

[Fugu]

15 hours ago, PigFish said:

I am beginning to believe in global... global.. I just cannot say it!!! 

Don't say it! Purely anecdotal observation, Piggy, purely anecdotal!!... haha

[PigFish]

2 minutes ago, Fugu said:

Don't say it! Purely anecdotal observation, Piggy, purely anecdotal!!... haha

... the next door neighbor's house is cool. Maybe I should turn the heat off...! -Piggy

[Philc2001]

On 10/27/2017 at 7:49 PM, PigFish said:

If it is not settled with cigar smokers, it is because they are people steeped in myth and groupthink. Sorry, but that is the truth about us as a group. (MHO)

-Piggy

True. I think most cigar collectors/hobbyists are in the hobby to enjoy cigars, and not so much for the science. Those that get into cigars in a significant way are often anal-retentive to an extent, but not disciplined enough to perform long-term controlled research with their collection. So the community in general relies on anecdotal (non scientific) observations - which tends to be biased towards group-think.

 

[SloppyJ]

1 hour ago, Philc2001 said:

True. I think most cigar collectors/hobbyists are in the hobby to enjoy cigars, and not so much for the science. Those that get into cigars in a significant way are often anal-retentive to an extent, but not disciplined enough to perform long-term controlled research with their collection. So the community in general relies on anecdotal (non scientific) observations - which tends to be biased towards group-think.

 

Matter of fact, I'm doing that experiment right now. It's not anything that I plan on getting very objective about (Although I have been weighing them in my log) but it will tell me how the changes will affect my personal opinion of taste. 

For many people, the activity of smoking a cigar is almost meditative. At least for me, sometimes it is common to get lost in thought about the finer details which probably led me to do this experiment. But I'm also weird  I have a degree in soil/water science so I enjoy the opportunity to gather some data.

[PapaDisco]

On 10/27/2017 at 4:49 PM, PigFish said:

If it is not settled with cigar smokers, it is because they are people steeped in myth and groupthink. Sorry, but that is the truth about us as a group. (MHO)

-Piggy

Ah Piggy, I don't think we're suckers for myth and groupthink.  I do however find that the second band on my LE helps restrict the flow of humidity into the cigar and keeps their rH constant.  

[Fugu]

59 minutes ago, PapaDisco said:

I do however find that the second band on my LE helps restrict the flow of humidity into the cigar and keeps their rH constant.

Ahh, Poppy, common knowledge!  . Even famous princes adopt it. 

[Wilzc]

Lol!!!

 

So I'm in Malaysia, relatively humid place. 60-80% RH average at around 30deg celsius

I can't care less for wood humidors so I've gotten myself a camera drybox that has an automatic humidity regulator.

It regulates by sucking humid air from inside, onto a desiccant, then dispelling the moisture off the desiccant via a valve.

 

 

I used to set the box at 69RH (Because I like the number 69) but I've now switched to 75!

At 75rh in temperatures averaging 28degs, it would seem to humid for cigars but they have been smoking really well!!

 

 

Ergo, I suspect there is ANOTHER variable in place here!! The outlet fan action, however mild its draw, is creating a low pressure environment!

At least a pinch lower than atmospheric.

So even at 75rh-80dF, which should point to high PMContent, I suspect the cigars are actually closer to 12% PMC

 

 

What would thy rebuttal be? Master Pig

 

 

[PigFish]

 

Temp and rH are linked. Furthermore taste plays the biggest role.

Know what you like, make a correlation between taste and storage conditions, experiment, and store to taste!!! -Piggy