Humidity versus temperature question

[jjdolphin]

I just read a post on the internet regarding temperature versus humidity for cigar storage.

The jist of the article was that different temperatures contain different levels of humidity. The higher the temperature the more water content in the air. I remember PigFish mentioning that before. Is this the true way we should be looking at our humidors?

The table states that if your temp is at 70F your hygro should show 70%, but if your temp is elevated, as it usually is where I live then your hygro should show less, eg. 80F should have your hygro at 55%. Basically if your hygrometer is saying 70%, but your temp is 80F, you are over watering your plant. Is this true or is 70% on your hygrometer a true indicator no matter what the temperature?

I am using 70% as just a general round number. So, if you like your smokes at 65% then you would do the appropriate math on the table.

TEMP/HUMIDITY

60 / 85%

61 / 83%

62 / 82%

63 / 80%

64 / 79%

65 / 77%

66 / 76%

67 / 74%

68 / 73%

69 / 71%

70 / 70%

71 / 68%

72 / 67%

73 / 65%

74 / 64%

75 / 62%

76 / 61%

77 / 59%

78 / 58%

79 / 56%

80 / 55%

[rfenst]

RH (Relative Humidity), not actual humidity, is what is important.

[jjdolphin]

RH (Relative Humidity), not actual humidity, is what is important.

I should have mentioned that the table is Temp/RH. So, basically, just because my hygro says 70%, if my temp is high then I am over hydrating the humidor.

I am just not that well versed in the science of it all, so I would like someone to confirm or deny the theory.

[Trevor2118]

I should have mentioned that the table is Temp/RH. So, basically, just because my hygro says 70%, if my temp is high then I am over hydrating the humidor.

I am just not that well versed in the science of it all, so I would like someone to confirm or deny the theory.

What has been advanced is the incorrect application of science to this "problem".

Firstly the statement "different temperatures contain different levels of humidity" is vague and effectively wrong.

A fixed volume of air at a given temperature can (only) contain a maximum amount of moisture.

As this temperature falls, the amount of moisture that this given volume can hold....reduces.

The percentage of moister actually in a given volume of air (relative to the maximum that it can contain) is its relative humidity. If the RH is 100%, the air is now saturated with water; called the dew point.

But the application of this science to cigars is wrong.

In the table you supplied, if you further reduce the temperature (below the 60 you quote), the RH will eventually become 100%...and the cigars would be sitting in condensate moisture. This is clearly not appropiate.

Edited April 23, 2012 by Trevor2118
"rises" corrected to :falls"

[Trevor2118]

The reverse is actually true. As the temperature DROPS the ability of air to hold moisture also drops....hence dew point, condensation on a glass, cold fronts causing precipitation, etc.

The rest sounds good though

Opps....I knew that

Post corrected.

[jjdolphin]

In the table you supplied, if you further reduce the temperature (below the 60 you quote), the RH will eventually become 100%...and the cigars would be sitting in condensate moisture. This is clearly not appropiate.

The article does mention that below 60 the air cannot hold any more moisture, hence the table ends there. There is no corresponding RH level that will give you an appropriate actual humidity.

It got me to thinking about my own situation where I am holding my cigars at 65F with RH at 65%, however the cigars seem too dry. I have another humidor at 70%, same temperature, and they seem dry to me as well.

[Trevor2118]

The article does mention that below 60 the air cannot hold any more moisture, hence the table ends there.

That bit is just plain wrong.

Have you ever calibrated your hydrometers?

[jjdolphin]

That bit is just plain wrong.

Have you ever calibrated your hydrometers?

Sometimes I think I calibrate and re-calibrate, and baby the cigars more than I smoke them. I am pretty sure they are calibrated to a few degrees up or down. I am using 4 different ones.

[ThatAlfonso]

I guess what you are getting at is it more important for the cigars to be in an environment with the same amount of moisture in the air regardless of temperature (RH will change at different temps) or the same percentage of water in the air (RH stays the same at all temps)? I have been understanding that the latter is the rule to follow but I am curious about the answer to this question too.

[brazoseagle]

This is like the bat signal for Ray (pigfish)

Come out , come out where ever you are! I've heard his hypothesis on this subject matter before, and it is informative.

[Trevor2118]

I guess what you are getting at is it more important for the cigars to be in an environment with the same amount of moisture in the air regardless of temperature (RH will change at different temps) or the same percentage of water in the air (RH stays the same at all temps)? I have been understanding that the latter is the rule to follow but I am curious about the answer to this question too.

Nothwithstanding any of the above.....the recommended storage conditions for cuban cigars (as stated by Habanos) is 65% to 70% RH and 16 to 18 degree C.

Thats 61 to 64 degree F.

No oddball theories better that advice.

[Wil]

This is like the bat signal for Ray (pigfish)

[LeafLover]

My head is spinning.

My cigars are at 58-61 rh for the most part and I love the way they taste and burn. I still dry box before I smoke. Construction is a whole different story.

I won't even go there with the temp as it fluctuates because I keep my wine fridges on a timer and cools during different parts of the day. But, I know I rarely see the temp above 68 F.

[davidsan]

I am able to keep a fairly steady humidity of around 65% but my temperature is always up around 21deg C.

[PigFish]

...what??? Who is... ??? Stop that damn ringing!!!

Oh, it is just my humidity post alarm on FoH!!!

Yes,,, I love H SA, hate guns, smoke robustos and I can't even spell psychrometric!!! -LOL

-Pig

[PigFish]

I hate being a forgone conclusion!!! -LOL

First some caveats. This conversation is going to cover a range of science as facts, my opinions and beliefs. In a lot of cases I will take a lot of time to separate the three, but frankly I just don't feel like crossing all my "T"s and doting the "i"s today. So understand this from the beginning please. Some of this has been empirically proven to myself, evidenced or read in the papers of others but I am not going to take the time to footnote it all.

Now that is out of the way, lets step back from this and look at what "you want" and separate that from "how you are gonna' get there."

Tobacco is hygroscopic. It adsorbs as well as absorbs water vapor and water (and visa versa). You know this already. The amount of water in tobacco affects is pliability and resilience to break (shatter) and its ability to burn. Furthermore, tobacco easily can hold an amount of water necessary to support microbial and fungal life. The question is, "What is the right amount of water?"

The right amount of water is a range depending on the reason that you are wetting tobacco. While it has been common amongst the enthusiast crowd to correlate the water in tobacco to the ability to smoke the cigar, as in the draw and burn, I have read very little in the writings of others regarding the amount of water in a cigar and the taste. I think this is very subjective of course, but I have brought this conversation to several cigar venues for discussion prior to viewing it in this perspective. In hundreds of years of tobacco consumption, I am not claiming it as original thought, but I do tend to focus on it far more than most others. I believe that the water in a cigar at the time of consumption is the single most important factor of taste that the cigar owner has in his power to control at anytime in the cigar's life.

Those are some of my beliefs... in a nutshell.

With that in mind, where should your cigars reside, as far as how wet they are?

I have concluded that most of us enjoy a rather broad range of cigar water content. Few of us really care about the content beyond "how the cigar smokes." Many have not made a correlation to taste and amount of water nor do they care. Some reasons to consider are our inability to easily test the amount of water and the rate of transfer of water vapor in a cigar at a relatively low temperature. We just don't have factual data and the data that we do have takes an enormous amount of time to compile in the real world. To weaken the subject further, our compiled data is completely subjective.

How long do you think it takes to move the water content out of a cigar where the equilibrium RH is changed 2% for example? How much water is actually moved from the cigar, as a percentage weight of the cigar? The work is slow, the data collected is completely subjective without precision instruments and controlled conditions!

Lets get back to water content for a moment. Here is a broad claim (remember my first paragraph now) about the water content of a cigar. Most of us enjoy a cigar that is somewhere between 8 to 12 percent water by weight. For the sake of argument lets just whittle this down to 10 percent water by weight.

Now that we know what we like, we need to understand how to get it there.

You need to understand water activity and the individual constants of water activity that each hydroscopic material possesses. Here is an example.

You put your cigar in an environment that is 70 RH and 70 DF (degrees Fahrenheit). Does this mean that because the RELATIVE HUMIDITY of air is 70% that the corresponding tobacco stored in it is going to be 70%? No it does not. The saturation rates, and abilities of air to hold water and the ability of tobacco to hold water are completely different. You must understand this to understand EQUILIBRIUM HUMIDITY and humidor psychometrics. OR, you just take another's word for it. This is what most of us do. We simply seek advice of the 'experienced' and go from there.

There are many factors that are at play when looking at the water activity of a specific material. I am not going into this in a lot of detail, you can find some of my many previous posts on the matter. It is important to note however that not all things attract or expel water vapor at the same rate. The correct terms are adsorb and desorb water vapor.

The key is to matching water activity levels. Unless you have the equipment to measure water activity you cannot do this. So most of us work through a starting point of advice and graduate to experience over time.

While I have some data on the adsorption and desorption of water vapor in tobacco, most of it surrounds industry interests in the subject, as in flue drying tobacco were tobacco is processed and not stored for consumption. While this data is interesting, it is not really applicable to us except that you begin to understand that tobacco does not really transfer water very quickly below 70 DF. In my experience however there is a rather steep change in the way tobacco behaves in the 60 to 80 DF range. The rate at which tobacco exchanges water appears to me at least, to be significantly different at 60 DF than at 80 DF.

This brings us to consistency of conditions and why temperature consistency is important. It is not only important because the amount of water (absolute humidity) in the air is different even thought the RH at varying temperatures may be the same, but it also plays a role in the adsorption isotherm of the product that we are concerned about and that is the tobacco.

Your goal then is to first control the conditions, both temperature and humidity of your cigar storage into a range that you can enjoy the cigars that you store and smoke, and that you can afford. This is always why I ask the question, "How do your cigars smoke?" And then I always answer, "Then why do you want to change them?"

Smoking is everything. Unless you have the means to measure water activity and actual water content and then a means to correlate the two to taste preference you are only guessing. Guessing is what most of us have done. We have tried, tasted, adjusted and tasted for decades. We do it again and again. We finally conclude that we have a preference.

The preference is "taste and smokability" to a given storage condition. This means that we have refined our taste to match a certain condition. It is then, the only reason why the condition is important. You see there is a generalized relationship that exists between temperature, RH and pressure of air to an equivalent water content in certain types of tobacco over time. And the fact that there are different types of tobacco in your cigar, such as ligero and seco for example and each one of those types of tobacco likely have varying adsorption isotherms, each cigar is uniquely different! This can be a process of controlled insanity if you let it.

If we consider then that our goal is 10 % water by weight in our cigar and if we had isothermal charts of our tobacco at a given RH of air, we could match our temperature to a given RH of air to find the right water content at a given temperature. You see there is one RH number at each increment of temperature within a physical envelope that defines the water activity of tobacco but I do not have such data. I don't think anyone does! I have researched it for years now and while I have a lot of experimental data of others, I don't have exactly what I want... What I have is my own experience!

We therefore have wisdom, practical experience and mentoring. That is the best that I can do!

First you decide on a starting point. You store and acclimatize your cigars. You smoke them and judge them. You start all over again. If you are happy with how your cigars smoke there is no reason to change. If someone convinces you that you are missing something you sample and try, experiment and explore. The cigar is very forgiving. The more you smoke, the more you experience, the more you conclude for yourself. There are shortcuts... we call them mentors, members here who will share advice with you. The magic of what works for you resides with you. Certainly not with me, certainly not with a guru or a product you buy. You will likely never have the perfect humidor for your perfect cigars. Hopefully, as in all things in life, you have what you like and are satisfied with what you can afford.

Cheers! -the Pig

[CanuckSARTech]

Good gawd, Ray, you are definitely back full throttle.

You gotta PM me your mailing address again buddy, I have some nice treats for you. (Misplaced your address to do a covert bomb, LOL.) I promise I'll send you lots of EL's and donkey dongs.

[jjdolphin]

I think there needs to be a mandatory humidity post every week!

Thanks Ray.

[Len]

Great discussion on the topic, I don't think i've ever seen on other boards this subject at such length and detail ...All I know is I use 65% RH beads and where I live the humidor stays around 70 degrees and my cigars smoke perfectly.