A lesson in humidor science.

[PigFish]

With all the questions that I get about humidors and humidity I thought I would share an interesting example that shows how humidity relates to temperature.

What you are looking at:

This is a non temperature controlled box that has about a dozen boxes of cigars in it. It is in equilibrium at about 65 RH. I put the box so the sun hits it in the morning and heats the box. Lets see what happens!

As the box warms, the red line increases, what happens to the blue line? Ignore the green line! The blue line drops. Why? The blue line represents RH. The water content in the humidor does not change, but the RH does drop in relationship with the rise in temperature.

As the box cools, the RH returns to where it was before. I thought it was a good pictorial of the process so I thought I would share. -

[fred170]

Nice. So in essence, we should not fear sun rays hitting the humidor for fear of drying out the smokes because the rH will return to equilibrium once the sun exposure is void.

I always thought of keeping my smokes in an area where there is hardly any light.

Great Info now if I can only move my humidor to the window without knocking down the wife's plants lol

[El Presidente]

Professor Piggy

[OZCUBAN]

Great post Ray

As always

Cheers OZ

[BradNC]

Thanks Piggy. I always enjoy reading your posts on this.

[aes8]

Would it be fair to say that a tight temperature controller is over rated as long as you kept your cigars in a cool, (implying small temperature swings 4-5 deg F) place and tightly control the humidity?

I think you know where I'm going.

Nice trend analysis btw.

[benjaminbbush]

Great Post Piggy. Now that I have learned my one new thing today, I am done. Peace out homeys!

[str8dog]

Not that you'd want to keep cigars at 80F, but would a cigar at 80F and 54% smoke the same as one at 69F/65%

[fred170]

Your making me think too much...lol. I feel like I'm back in college taking a dreaded Math course, or was it Physics...either way it is all relevant........

[aes8]

Your making me think too much...lol. I feel like I'm back in college taking a dreaded Math course, or was it Physics...either way it is all relevant........

Open loop Control Theory, I'm just saying....

[Orion21]

It wouldn't smoke the same because the beetle holes wouldn't facilitate an enjoyable smoke...lol

Not that you'd want to keep cigars at 80F, but would a cigar at 80F and 54% smoke the same as one at 69F/65%

[str8dog]

It wouldn't smoke the same because the beetle holes wouldn't facilitate an enjoyable smoke...lol

True that! LOL, hence the disclaimer, but is the moisture content of both cigars the same?

[PigFish]

True that! LOL, hence the disclaimer, but is the moisture content of both cigars the same?

I have been meaning to get back to this, just a little busy.

Each hygroscopic entity has, can have, a different absorption isotherm. The way I see it these absorption isothermal graphs are not straight lines and do have some dependence on temperature.

So while the air in the chamber is the same, and it contains the same amount of water g/m3 by weight, the ability and for lack of a better term "magnetism for water" of the warmer air, now at a lower RH will look to rob your cigars of their water if left unchecked.

While you are concerned with the "absolute water content" of your cigars, you have no convenient way to gauge it, other than by smoking it. Knowing tobacco is hydroscopic allows you to control the water content by controlling the environment. This is why you own a humidor!!!

So to answer your question, no! If your cigars are left at 80 deg. F at 50 RH they will lose water to the air and dry out.

If one ever wondered why I have a fascination and fanaticism with climate controlled humidors; this is why. It is a good thing that cigar are not really delicate. If they were we would have all ruined them by now!!!

-Prof. Piggy

[Guest 321contact]

With all the questions that I get about humidors and humidity I thought I would share an interesting example that shows how humidity relates to temperature.

What you are looking at:

This is a non temperature controlled box that has about a dozen boxes of cigars in it. It is in equilibrium at about 65 RH. I put the box so the sun hits it in the morning and heats the box. Lets see what happens!

As the box warms, the red line increases, what happens to the blue line? Ignore the green line! The blue line drops. Why? The blue line represents RH. The water content in the humidor does not change, but the RH does drop in relationship with the rise in temperature.

As the box cools, the RH returns to where it was before. I thought it was a good pictorial of the process so I thought I would share. -

aww i see the graph is from a lascar usb temp. I have one of those as well.

[traded]

you know, I can understand the most nuanced complexities of the human brain and human psychology, however this stuff is very difficult for me to get my head around. I guess Im missing one important piece: Why do we need more water in the air as the air gets hotter to maintain a consistent RH?

Here is my good old college try:

Im imagining that as air gets hotter it becomes less dense. I guess as the air gets less dense there are less gas molecules in the air per volume, so the water vapor per volume also goes down????

so you need more water vapor per volume unit when the air gets hotter to keep the same absolute level of water in the volume unit of air?

so if I have 10 water vapors per cubic meter at 60 degrees F lets say giving us a 65 RH...

if the temp goes to 80F the number of water molecules per cubic meter goes down to, lets say 6 water molecules and the RH is now only 45. so you need to pump more water molecules into your air space to raise the RH?

Basically is it all about air density and the diffusibility of water in air (i.e. as the air/gas molecules become farther apart in hotter air, so do the water molecules?)

Bare with me Piggy, I'm out of my element here.

david

[ChanceSchmerr]

Love the posts, Ray - great thread!

It's great to have to dust off the old engineering knowledge deep somewhere in my brain and actually relate it to cigars!

[bob25]

Why in the wine coolers when the temp drops the RH drops too and not as your graph shows?

Is it because of the cooled air?

[PigFish]

Why in the wine coolers when the temp drops the RH drops too and not as your graph shows?

Is it because of the cooled air?

I will try to get to some of the other questions a little later. This one is easy. The RH drops because you are confusing the system by adding a variable beyond temperature. You are actually condensing water on your cooler and removing water from the system because cooler air holds less water per g/M3. You are not only cooling air in your humidor, you are conditioning the air by rapidly cooling it below its dew point and removing water as a condensed liquid.

I was doing a little farting around with the calculator this morning and ran some numbers. I have always told people to be very careful how much water they put in their humidor. Here is an example of what I mean!

You have a 2 ft3 space you call your humidor. At 68 deg. F, the difference in actual water in the air at 60 RH verses 65 RH is....

You know, I am gonna' have a little fun. How much do you guys think it is? Volume, weight, you name it!!! Post your guess, I'll post my answer a little later. -Piggy

[rsd]

I've built my own humidor monitor, using an arduino microcontroller board, a cheap resistive humidity sensor and a LM35 temp monitor:

Controller image

I've only had it running for a short time, but here is a graph of about a weeks worth of data for anyone interested. It is just a simple desktop humidor, sitting on the desk behind me in my study.

The data (might take a while for the graph to load, be patient):

https://spreadsheets.google.com/spreadsheet...uthkey=CJybpb8P

This controller is going to have a relay added and control a wine cooler + active humidifier at some point in future, this is just the first step so I can learn how to do everything needed It should also be noted that I am not 100% certain my method of working with the humidity sensor is ideal, so don't read too much into the data.

If anyone wants to know more about this, I don't want to derail this thread so please post here. I just wanted to contribute some data.

[fred170]

I've built my own humidor monitor, using an arduino microcontroller board, a cheap resistive humidity sensor and a LM35 temp monitor:

I've only had it running for a short time, but here is a graph of about a weeks worth of data for anyone interested. It is just a simple desktop humidor, sitting on the desk behind me in my study.

The data (might take a while for the graph to load, be patient):

https://spreadsheets.google.com/spreadsheet...uthkey=CJybpb8P

This controller is going to have a relay added and control a wine cooler + active humidifier at some point in future, this is just the first step so I can learn how to do everything needed It should also be noted that I am not 100% certain my method of working with the humidity sensor is ideal, so don't read too much into the data.

If anyone wants to know more about this, I don't want to derail this thread so please post here. I just wanted to contribute some data.

Now that is straight out of the Jetsons....

[Professor Twain]

I'll guess half a fluid ounce... not much

[semery74]

Here is a great online humidity calculator. If you switch to the advanced tab, I think the thing to pay attention to the most is PPM, which is the actual volume of water in contact with your cigars. I would think that vapor per volume would remain reasonably static during a daily fluctuation of probably an average of 2 degrees between day and night, if your home has air conditioning.

http://www.vaisala.com/humiditycalculator/...calculator.html