I recently got heavier into cigar smoking and want to start storing cigars at home in a humidor. Like most things that become a sort of hobby of mine, I research the hell out of my new fascination.
So while learning about humidors, I discovered that the cigar community is split on whether or not the relative humidity the humidor is kept at should change based on temperature. Below I’ll paste two differing opinions along with the rationales:
Quote one is correct, as long as it doesn’t actual condense the water in there… which would be easy to do with the AH at 70%… so you have to keep the temperature up. Thats what quote two says anyway… drop the temperature, and your having trouble with humidity… the water won’t be in the air… water droplets will then promote growth of low temperature loving stuff. You can get mould in the cold !.
As long as the temperature is above the point of condensing water droplets, it won’t matter as to what temperature it is ? Except the temperature changes destroy the cell walls… for many reasons. Not just due to the change in RH.
So the most important thing to do to preserve your tobacco is to keep the temperature and humidty stable at that narrow range.
I always apply the reductio ad absurdum rule to this kind of question. I am confident that cigars would not do well at very high or very low temperatures, whatever the humidity, so it follows that they need to be kept at a reasonable temperature. It may well be that your sitting room/cellar/whatever stays at these temperatures all the time, or you may need a store that can maintain what must be a fairly expensive stock, at a constant.
Of course it’s best to keep them at “reasonable” temperatures, but what I’m asking basically is regarding whether or not relative humidity or absolute humidity is more important.
It makes sense intuitively that if we take for granted that cigar is best at a relative humidity of 70 if it’s 70 degrees, then if instead the cigar is kept at 75 degrees it will be better if the RH is kept at a lower number because 75 degrees can hold more water in the air.
The “amount of water in the air” is by itself of no consequence; what is of consequence is the ratio of the water’s partial pressure to equilibrium vapor pressure, which is precisely what relative humidity is. Think of equilibrium vapor pressure as the pressure of fully saturated air at a given temperature, and partial pressure as the actual pressure of whatever water vapor is actually there. So the ratio – the relative humidity – determines the tendency for water to want to turn into vapor – the evaporation rate – and therefore the tendency of your cigars to either dry out or absorb too much moisture. A low relative humidity and high temperature will dry things out more quickly, whether it’s cigars in a humidor or laundry on a clothesline – even though the absolute humidity may be much higher, because of this vapor pressure differential.
Maybe there’s something magical about how tobacco reacts to temperature, but no such thing has been suggested, and the rationale in that second article about AH vs. RH is absolute unscientific nonsense. It actually thinks you should store cigars at 96% humidity if the temp is 61°F! I would imagine that after a while they’d probably come out sopping wet.
This is a table I use for predicting wood MC, not sure how it would apply to cigars. It looks like the Rh of 70 is the magic number where exact temps are not that critical. When I copy and pasted the temps did not line up with the MC.
I guess I have a mistaken notion of what relative humidity is, and your explanation is over my head. I’ll take your word for it though and not worry about changing the relative humidity of a humidor based on temp fluctuations. Thanks.
Notice how equilibrium moisture content drops with higher temperature! For wood, it’s exactly the same at 50 deg. and 60% relative humidity as it is at 100 deg. and 65% RH. It doesn’t change much with temperature but if anything, as temperature rises you would want to very slightly increase (NOT decrease) RH to keep the moisture content the same. This is the exact opposite of what article #2 claims. In practice, though, for nominal temperature ranges and most materials RH should be all the matters.
Not being a cigar smoker myself it is easy for me to imagine individuals tastes to go a bit below and above what is considered optimum MC. Is this the case?
Not really. Everyone wants a cigar that doesn’t burn too hot, too fast, have a poor draw, become un-lit, have the wrapper split, etc. That is going to happen at the right moisture content. People have RH preferences that they want their cigars stored at to achieve that moisture content, but the differences probably mostly lie in there past experiences with thinking they know what the cigars they smoke are stored at at their favorite cigar shop or their hygrometers not being accurate in their humidors (which is very common) rather than actually having different moisture content preferences. Although some cigars require a slightly more or less moist environment. For example, a less-tightly-rolled cigar burns better when stored at a slightly higher than average RH.
This “At 70% relative humidity (a measure which by definition is independent of temperature)” means 70% relative humidity is the desired RH for cigars, regardless of the humidor temperature (for reasonable ranges of temperature)."
Whereas this “.… Absolute humidity, relative humidity and vapor pressure all vary with changes in air temperature” means given a fixed amount of moisture trapped in a sealed container, as the temperature goes up the relative humidity measurement will go down and vice versa.
The first statement is about cigars, the second about physics.
Combining them gives the practical result that:
You DO want to maintain a fairly even humidor temperature.
If the humidor gets much hotter or colder than normal, you DO want to add or subtract moisture to maintain 70% RH.
You do NOT want to target different RHs at different temperatures.
re. Cigar storage: What’s with the copper lining in cigar humidors?
Attended an Estate Sale of an old boy who knew his cigars - a humidor large enough to hold several dozen cigars (and was fashioned as an end table), and a gorgeous smoking jacket.
The humidor had sheet copper tacked onto all the compartment’s surfaces.
I have no idea why copper would be used. My wooden humidors are all lined with Spanish cedar. It does require conditioning with humidification solution occasionally, especially in our dry climate. But it holds the humidity well, as it is supposed to, and my cigars are fine.
It seems to me that copper sheathing wouldn’t hold humidity at all. Perhaps the old boy didn’t know his cigars and humidors as well as he thought?
