Confusing Results w/ Hygro Calibration - Need Help!

[macster]

Being a noob to the cigar world this is all virgin territory to me, so any help is greatly appreciated.

Several weeks ago I purchased a Hygroset Adjustable Hygrometer and a Humidipak 1-Step Calculation Kit. To calibrate I placed th hygro inside the Humidipak bag, made sure the seal was tight and then placed the bag inside a small Tupperware container with a translucent lid to insure an airtight enviornment. I set it in a dark area of a room with the ambient room temp being 75*F. Let it sit for 36 hrs and the final reading was 73% RH. I adjusted the dial 2 clicks clockwise and pressed the re-set button. I then re-did the test for another 36 hours the same way and the hygro stayed at a steady 75%.

I then purchased a cheaper Springfield temp/hygro unit from Wal-Mart a week ago. I did the test the same way with this unit. Final RH reading was 80% so being that it is not adjustable I know I have to subtract 5 points from its claculation.

Now here's the confusing part. I realize that storing my cigars in my humidors at a room temp of 75*F may be a bit risky (even though I do the 24/72/24 fridge/freezer/fridge routine) I came up with a solution. I am a homebrewer and have a chest freezer in the garage with an external Johnson Thermostat Controller hooked up to control my fermentation temps. Currently I am using it to store my bottled beer. I figured If I set the temp at 65*F it would be a nice cool enviornment for my humidors. I also keep 3 large containers of Damp-Rid in the freezer to keep the condenstion down and prevent any rusting of the seams. I set the controller at 63*F with a 6* differential to keep the compressor form cycling off and on too often. Therefore when the temp reaches 68*F the unit kicks on and brings the temp back down to 63*F.

So I figured perhaps it would be a good idea to calibrate both hygros together in that particular enviornment since that is where they'll be working. I did the same routine with both hygros in the Humidipak bag placed inside the Tupperware container. Set in the chest freezer for 36 hrs. Final check revealed both reading a temp of 66*F. However, now the adjustable Hygroset which I thought had already been calibrated to 75% read 78% RH and the Springfield read exactly the same, 78%!! No more 5 point difference now as previously recorded calibrating it at 75*F in the house.

I'm totatally confused as what to make of this and which readings are accurate.

Any suggestions are welcomed. THANKS!!

[Ozz1113]

Did you try calibrating the adjustable at room temp. for a 2nd time?
I wouldn't worry too much about keeping your cigars at 75 degrees.

About the freezer, I'm guessing b\c it's more of an air tight enviroment, your results may vary =)

[shilala]

Humidpak 1 step calibration kits are the suck.
Do a salt test and you'll get proper results.

To qualify this startement, I currently have 40 of them sitting behind my desk. I've tested them against everything I could think of and tried them in multiple situations and temperatures.
The results of said effort:
They are a cruel, sick joke.

Use a mayo lid full of salt in a gallon ziplock. The cost is roughly 30 cents and you'll gather perfect results.
There's a reason why they give one step calibration kits for free, by the way.

[(909)]

Salt test is on the money every time without fail.

[SeanGAR]

Thing about the Bovedas is they also use saturated salts to control humidity; the salt is stored inside a water permeable membrane/paper and the salt is not NaCl, but something different for the various humidity packs (probably lithium acetate for 69, strontium chloride for 72 and cupric chloride for 65).

The thing about the different salt solutions is that they behave differently with temperature. Specifically, lithium acetate produces a humidity of 71-68% at 15C-25C. Strontium chloride ranges from 75-71% from 15-25C. Sodium chloride maintains constant 75% over this temperature range (15C=59F, 25C = 77F).

The sensors in your hygrometers are not responding in a linear fashion. I would use NaCl rather than one of the Bovedas as it produces a much more linear humidity with different temperatures than most other salts.

Humidity data for salt solutions from Rahman Food Properties Handbook 1995 CRC press Table 1.2 p 5.