Absolute Humidity

Lasabar:
So do I take any solice in the "Relative Humidity"? or is that if it's 60Degrees or 80Degrees it should always be at 67%Rh???

we always talk about RH.
"whats your RH?"
"i keep my humi at 65% RH"

Wikipedia states:
The relative humidity of an air-water mixture is defined as the ratio of the partial pressure of water vapor in the mixture to the saturated vapor pressure of water at a prescribed temperature.

uhh... what? Pressure? do i now need a barometer in my humidor?
no. no you dont. vapor pressure is basicly the the pressure that water feels to vaporise.

damn science getting in the way of a good time...instead of dealing with the vapor pressure and all that we can estimate RH if we know temp and the dew point temp. ...long story very short when the temp changes the dewpoint does as well. the lower the temp the lower the dew point the less water in the air. bla bla bla science bla bla bla...

when we say "RH" we actually mean "RH at 70* fahrenheit" since 70/70 is accepted for some reason in the cigar world we all say RH on the assumption that the humi is at 70*f.

the reality is we are all talking about "AH"
if im not mistaken our hygrometers are reading Abolute Humidity. thats easy to understand. Absolute humidity is the mass of water vapor per cubic meter of air.
so as long as you keep your humidor at bout 70*f you can speak in RH if not....
personally i plan in staying with RH. its what im used to.

one more fear. If you have your humidor at 70% AH and the temp sudenly drops outside your humidor to about 35* would that cause some of the water to condense on the inside walls of the humidor?

ok... i hope i didnt botch that up too bad. Im not a meterologest, im a cook.
...who smokes cigars.

Find more posts tagged with

Comments

Lasabar

dutyje:
Lasabar:
madurofan:
Well unless its passive. What is your humidification lassy?
Got me two large discs of "Heartfelt Humidity Beads" at 70% but they are a little under-filled for i want to gain 67%
when you say "under-filled" -- you mean some of the beads are white? or do you mean it's not filled all the way up to the top with distilled water? The latter will keep you running high for qutie a while.

I mean one disc is 80-90% clear and one disc is 70% clear

dutyje

then what you're seeing doesn't make sense unless your hygrometer measures absolute humidity (I thought this was rare in a non-commercial hygrometer) or maddy's air conditioner theory applies.

kuzi16

i find that if the air is more humid in general (summer months) the beads do better way under charged. about 10% (if that) of my beads are clear at the moment. im at exactly 65% ... and they are 65% beads.

madurofan

How the hell did you get your beads to dry out? I've taken the hair dryer to them for so long they were scolding hot but still not dry. I let them sit out for a few days no more dry than when they started.

kuzi16

i crank up the AC and set them in front of a vent for a few hours. worked for me.

madurofan

hmmm ... might give that a shot. or maybe use the cool option on the hair dryer as well.

kuzi16

if you can spread them thin when you do this. more surface area.
...maybe in a glass baking dish.

urbino

Hair dryer on low worked for me, maddy.

Vidarien

It seems like some are really interested about this topic, im a chemical engineer and this is my bread and butter, so ill recap and explain in detail most of what was mentioned for the reallllllllly curious (and because i clearly have nothing better to do!).

- The difference between absolute humidty and relative humidity is based on temperature. The reason its a relative humidity is because its relative to that temperature. Humidity, as a measurement of the partial pressure of water per volume of space (or, a percentage, as you always see it), is completely dependent on the temperature of the volume that it is in. As the temperature goes up, the pressure of that water must rise as well, given the volume itself hasnt changed, via the ideal gas law. (Theres exceptions to that rule, but thats far beyond the scope of the discussion here). So, as a result, the maxium pressure of water in air increases, and water is absorbed into the gas phase via evaporation to meet that equilibrium.

I know thats kind of confusing, but i'll leave it at, absolute humidity can not be measured with a percentage, it can only tell you how much water vapor is in a certain volume of space. That in itself tends to be meaningless for common everyday uses, (aside of scientific/engineering calculations), which is why people make it relative to the dew point at a specific temperature, hence relative humidity. At 0% relative humidty, there is absolutely no water vapor in the air, at 100% relative humidity, the air is completely saturated, and should any water vapor at all be introduced into the volume, it would immediately condense. (Its why the outside of your beer gets wet!) Actually, theres a little more to that, and it leads to exactly what some of you are wondering about, temperature changes in a closed humidor.

So, like i explained above, the temperature of the volume (air) directly influences the relative humidity. To answer someones question earlier, the changes in your relative humidity make perfect sense when temperature changes. In a closed box, if the temperature rises 10 degrees, the relative humidity must go DOWN. Heres why. You have a pretty constant amount of water vapor in the humidor, and then suddenly..within a few hours your box is warmer. Well, the capacity for water to remain in the vapor phase goes up! As a result, the total humidity relative to the dew point (100% RH) must go down!. Its like taking a glass of water and pouring it into a bucket, and then taking that same glass of water and pouring it into a tub. The water in the tub is far less a % of the whole than with the bucket.

Now, the reverse to answer another question i saw. Say you had your humidor in the basement in a really hot house with all the windows open, and it was about 75 F down there, and you had a good 70% RH in your humidor. Then you close all the windows, turn on the AC reaaallly low and forget about your humidor. Well, the relative humidity is going to spike, because the capacity of water in the gas phase will go down quite a bit as your basement really cools down, and...if it hits the dew point (about 62 degrees assuming you were running at 70% RH)...everything from then on is condensed water in your humidor.

Disclaimer: What I said above is in theoretical conditions. It would happen eventually but not immediately because the temperature of the air inside the humidor wouldn't cool as fast as the basement air due to the wood seal. How long it would take would involve me and a whiteboard with lots of numbers and symbols, and im not that crazy.

I hope this serves the interest of those that really wanted to know the deal behind RH and humidors.

Edit: I guess i misread. I didnt see that someone said their RH went down along with temp. If you meant in your house itself, then the AC explanation given was completely valid; if you meant inside your humidor, i would wonder if your humidor had a secure seal? You probably wouldnt notice significant humidity changes in your humidor if it was hot and humid in the area surrounding it assuming a bad seal, given diffusion would be much slower. But once AC was on, the difference would be much more pronounced. This is just my opinion though.

pilot711

Great post! Very informative. Thanks.

kuzi16

Vidarien... that was great

post more often.

madurofan

kuzi16:
Vidarien... that was great

post more often.

WHAT HE SAID!!! Thanks!

I have a question for you, and I hope you come back and read this. I'm using the 70% beads, and I'm storing my humidor inside a wine fridge kept at 65 degrees. Being that the cooler 65* air has the capability to store less humidity would that cause the beads to saturate the air more than 70%? I guess I'm asking if you think that the beads are designed to maintain the 70% RH at 70* and if you change the 70* then it messes with the beads ability to accurately maintain a RH of 70%?

dutyje

Thanks, vidarien... that was very well written. Please stick around and give us information like this more often!

Vidarien

madurofan:
kuzi16:
Vidarien... that was great

post more often.

WHAT HE SAID!!! Thanks!

I have a question for you, and I hope you come back and read this. I'm using the 70% beads, and I'm storing my humidor inside a wine fridge kept at 65 degrees. Being that the cooler 65* air has the capability to store less humidity would that cause the beads to saturate the air more than 70%? I guess I'm asking if you think that the beads are designed to maintain the 70% RH at 70* and if you change the 70* then it messes with the beads ability to accurately maintain a RH of 70%?

You know, thats an interesting question. Humidity beads are essentially a certain level of silica gel or similar desiccant packed into a semi-permeable barrier. And, all desiccants are affected by temperature and humidity. The humidity is taken into consideration by the designer (its why they can make 65/70/75% equilibrium packets). But, as to temperature...science would suggest bead absorption would decrease at a lower temperature, leading to a higher RH...however, on the flipside, the equilibrium point between the gel/water shifts slightly in favor or more absorption overall. So really the two factors work to cancel each other out to a degree. This is all highly theoretical, but, it does show a bit of the science behind why they really are "self-regulating". Its dependent on a lot of things, but, absent of any manufacturer specification, i realllly doubt a 5 degree difference in temperature would change the performance of the bead significantly. Certainly though, if 70% is critical to you, i would advise you to test it in 65/70 F atmospheres to find out for yourself. These comments are just what I would suspect.

madurofan

Thanks for that insight.

Vidarien

Sure. Unfortunately, all of the things i'm saying are just theory. The problem between science and the real world is, we dont keep our humidors in laboratory conditions. Theres pretty much a countless number of other factors that can come into play, so its always possible the exact opposite of what I may suggest can happen. To be tried and sure, if its important to me, i always test it out myself and dont leave anything to chance.

madurofan

Well theory is all we can ask for at this point and we appreciate your insight. Do you use beads?

Vidarien

Well, actually, im in the process of seasoning a new humidor with a seasoning packet (i've decided I do smoke enough to actually buy online/store them instead of driving to the B&M when im in the mood). I was using the onboard device but I may switch to beads. I overfilled the device last nice and the backing was weak anyway so it fell to the bottom and left a nice moisture stain. I'm hoping that will dry out soon without any damage. I'm starting to get myself paranoid about humidor warping, one of the lips on the side of the lid has a slight bit of empty space between it and the lid itself, and it keeps agitating me every time i see it.

madurofan

Stick a dollar bill in there and try to pull it through ... if its difficult its got a good enough seal, hows that science for ya? Despite what you may believe a perfect seal is not necessary nor desirable you want some air exchange just not enough to affect the RH.

Vidarien

Yeah, i couldnt just take it out, it required a little bit to pull the dollar through. Sitting at about 69%/71 F in there, but, thats with the 84% seasoning packet still in it, i guess it still has some seasoning to go.

madurofan

Did you calibrate the hygro? Wait your a scientist, sorry

Vidarien

Calibrated and with a digital in there for backup after my analog calibration went sour. The deviation of error on the analog naturally is quite high.

madurofan

Yea for the most part they're just really for decoration. Most of us on here just use digis for everything.

waterman3923

Ok I am new to this so bear with me please. I have a new humidor which holds 150 cigars. I wiped down all the sides and the three shelves which are cedar with distilled water. I have maybe 50 cigars in it now and my temp is 75.9 and humity is 75%. So is this telling me that I need to remoisten the cedar again that its not seasoned? I have some more cigars to add to it but will that make everything worse? I have a Large Rectangle Humidifier with distilled water and check it regularly.

Ok I read the posts here and cracked the door of my humidor oh may 2 inches and in about 20 minutes my temp is 75.2 and humidity is 66 %. I have a weather station and the temp in the room is 77.0 and humidity is 47 %. So I would like some feed back on what I need to do.

Thanks,

Charles

kuzi16

seasoning takes longer than just wiping down the inside with distilled h20. Infact, i think the slower the better. I dont wipe down the humidor ever. (i did on my first one but thats not the point) id just leave a shallow bowl of distilled water in there for a while. once the RH is above 75% for a day or two i would take it out and put in your humidification device and cigars. the bowl method is used so that you dont run the risk of warping any wood by moistening it unevenly when you wipe down the inside.

if your temp and RH is 75 and 75 then you are a bit high on both. much higher and youll have to start to worry about mold or beetles. Usually the seasoning proscess is done without cigars in the humi. i doubt any real damage has been done to them so id take em out and put em in a tupperware or some zip locs.

Vidarien

waterman3923:

Ok I am new to this so bear with me please. I have a new humidor which holds 150 cigars. I wiped down all the sides and the three shelves which are cedar with distilled water. I have maybe 50 cigars in it now and my temp is 75.9 and humity is 75%. So is this telling me that I need to remoisten the cedar again that its not seasoned? I have some more cigars to add to it but will that make everything worse? I have a Large Rectangle Humidifier with distilled water and check it regularly.

Ok I read the posts here and cracked the door of my humidor oh may 2 inches and in about 20 minutes my temp is 75.2 and humidity is 66 %. I have a weather station and the temp in the room is 77.0 and humidity is 47 %. So I would like some feed back on what I need to do.

Thanks,

Charles

Everything you said made perfect sense. I'm not one of the pros, but i assume you're trying to lower the temp and humidity to around 70/70? You wont be able to cool it down in a room at 77 degrees. Humidity you can fix easy enough by letting some out and trying to restabilize. If you use beads then it should hit the mark naturally; if you're using the onboard humidifer and you keep overshooting, id drain the device and use less water until you have a good fit.

waterman3923

Thanks I will take out my cigars and put in the bowl of distilled water for a few days and follow your advice. I have no cigars over a few weeks old so I dont think anything will be hurt. Where can I get these crystals ( a link would be great) and would I use them in addition to or in place of my current humidification device?

I got these instructions from where I bought my humidor: "Setup is very simple and you do NOT have to be as careful as you may think. Cigars are very forgiving. Simply wipe the inside down with Distilled Water - you can use a sponge or paper towel. Then pour Distilled Water into the humidifier sponge until it is full (you can also soak it in small container.) That's really it."

I already know I need to get a larger humidor one that holds 300 to 500 cigars but I can't find one that I like and can afford lol. One of you mentioned having an aging humidor so a dumb newbie question. If I get in some cigars today how long should I have them in the humidor before they are at their best to smoke? Thanks for all the great advice.

Charles

kuzi16

all of these are very good questions. However, we should try and keep the topic on track. many of the questions that you have can be answered if you just flip through the 101 section and start reading. Feel Free to PM me with more specific questions if you cant find it here or post your own thread. all the guys here love cigars and love discussing all kinds of aspects of cigars. this thread for instance was about the difference between relative humidity and absolute humidity, and how those differences may or may not impact a cigar at a fundimental level in a lab setting. ... pretty hard core.
if you are just getting your toes wet in the ocean of cigars a great place to start is right here in the cigar 101 section. we arent that old of a forum and you should be able to flip back a few pages and find what you are looking for. If not, or if you have a sepecial situation, start your own thread and we will discuss at great length what to do and why.
a good time will be had by all.

waterman3923

Thanks kuzi its like another hobby I have in the beginning I had to read, read, read but I have one more question related to this topic. I found a "Le Veil Digital Humidification System" for a really good price. Would something like this be a good investment? According to the ad description its totally automatic and I can set the humity to whatever I want to maintain my humidor at. Thanks again and I will go to Cigar 101 and do some reading.

Charles