Cigar Geeks

Looking for thoughts and suggestions regarding hygro calibration. My story to date...

I've been doing calibration using the salt method ever since I started the hobby. When I got my new tower though, I grabbed a Boveda calibration kit. Seemed pretty easy, so I thought I'd give it a shot. If nothing else, it seemed like a pretty thick bag I could reuse as opposed to Ziplocs. I went ahead and used it to calibrate my three wireless tags and two CI blue digital hygros (same hardware as the Xikar rounds, but blue cases instead of black).

Unfortunately, I've been getting some weird behavior from my wireless tags. A couple days ago I decided I'd recalibrate the 3 tags and a CI hygro. I spent almost 3 days using salt in the calibration kit bag, adjusting the different hygros.

After they were all looking good and stable, I pulled the salt and inserted a 60g 65% Boveda (the kit only comes with a small 8g 75% which I used originally). It was a tight fit in the calibration bag, and the hygros immediately jumped to 67-68%. The blue hygro read 68%. Averaging 2-3% above the rated Boveda pack.

I thought maybe there was an issue with using such a large Boveda pack, so decided to quickly change out to two 8g 69% packs. The hygros very quickly stabilized at 70.5-71%. The blue hygro read 72%. About 2% above the rated Boveda pack.

This morning I removed one of the 8g 69% Boveda packs to see what effect that may have. Seems to have had a small effect, but no idea why or how. Going to leave it this way until tomorrow morning to make sure I get a 24 hour stable reading. Next step after that I will try the single 8g 75% Boveda pack again.

(https://lh3.googleusercontent.com/-KVJUJxCFdIE/VrpD83YSQTI/AAAAAAAAUDo/JKiBG_w-YwE/s800-Ic42/Hygro-Test.png)

 

 

tl;dr

It seems to me, that either Boveda packs are consistently ~2% over actual RH, or the salt test is actually ~2% under actual RH. Will update with final results for this in the next few days, but wondering what people trust more, salt or Boveda?

I have always had difficulty making a proper supersaturated salt solution for calibration (and I mix chemicals for a living), so I just don't trust the method.

The other issue that I have with the salt solution is that you are probably nearing the upper end of the capability of the hygrometer.  It may not read well at that extreme, so that could have a negative effect on your calibration curve.  For any measurement instrumentation (without going into a full gauge R&R), it is good practice to calibrate on the upper and lower limits of your expected measurement range plus a known point in the middle to check for any accuracy offset.

We would like to believe that the range of the hygrometer that we are working in is small enough that we can reasonably expect linearity of measurement, but that is wishful thinking.

I have always had an issue with most hygrometers using a single point calibration.  Your multi-point check is a good one.  Unfortunately, you have no way to know if your standards (the Boveda packs) are precise and or accurate for your conditions (temperature and pressure).

I like the Boveda Calibration, I have a tough time trusting the saturated salt method.
Never had trouble with calibrating with the Boveda kit
Just my 2 cents

My cigar is smoking fine so my RH is ok. :biggrin:

Just changed the battery in one of my smaller hygrometers this morning and put it in a box with an analog meter that always holds at 70% and in just a few hours it read 70% so that's good enough for me~! :shades:

 Although, I will let it remain until tomorrow to confirm it stays at 70% .......

  I check my two towers from time to time with a electronic Medical Thermometer/Hygrometer I received from a friend a long time ago to check them and they always read the same as the digital displays after a few hours.........

QuoteJackal - 2/9/2016  3:04 PM  I have always had difficulty making a proper supersaturated salt solution for calibration (and I mix chemicals for a living), so I just don't trust the method.

The other issue that I have with the salt solution is that you are probably nearing the upper end of the capability of the hygrometer.  It may not read well at that extreme, so that could have a negative effect on your calibration curve.  For any measurement instrumentation (without going into a full gauge R&R), it is good practice to calibrate on the upper and lower limits of your expected measurement range plus a known point in the middle to check for any accuracy offset.

We would like to believe that the range of the hygrometer that we are working in is small enough that we can reasonably expect linearity of measurement, but that is wishful thinking.

I have always had an issue with most hygrometers using a single point calibration.  Your multi-point check is a good one.  Unfortunately, you have no way to know if your standards (the Boveda packs) are precise and or accurate for your conditions (temperature and pressure).

I see the salt test being touted as the best method all over the place, interesting to see a contradictory perspective.

My temps are pretty stable, and when stable, I can see the humidity fluctuations are in sync with my temp fluctuations. Here are my temps the last 30 days as recorded by the tags...

(https://lh3.googleusercontent.com/-E3UcvUntgTc/VrplV5SL9XI/AAAAAAAAUD4/X9OFLvFCTkw/s800-Ic42/Temp-Test.png)

That funny spike was when I moved the tags to the calibration bag and tried to blow into it to give it more air.

I also found it interesting that in the RH chart, tag 0 (upper shelves), was placed upside down, the sensor holes in direct contact with the Boveda. I actually find it rather amazing how much these readings fluctuate at a tenth of a %.

I have 62%, 65%, 69%, and 75% 8g Boveda packs. Maybe when I'm done I'll  calibrate at 65% and then check the differential for the other 3. After that, I'll just keep tabs on how well things are smoking and adjust the humidifier to taste, regardless of RH readings.

It's not my fault some nerd here posted about these wireless tags and made me by some. Graphs are like blinky lights. I can't top looking and tweaking.
 :biggrin:

Ted, I went through through this a few months back with 3 different hygrometers.  Here is the thread to it:

http://www.cigargeeks.com/index.php?topic=35153.0

I found that there are alot of variables as Jason explained with the salt test, mixture, type of baggy you use (some are thin and porous) all can affect the salt test.  Xikar claimed that their hygrometer was @ 75% when they tested it in their lab.  I call BS and won't buy another Xikar because you cant calibrate them.  I think the closest test would be the Boveda but Xikar disagreed in talking to them.  

IMO, if you feel you get a good reading with the Boveda pack you are going to be with in 1 or 2 percent, I would call it all good.  If you use a good humidifier, IE Beads, Boveda, yes even kitty litter or a Electronic humidifier, and use the hygrometer as a guide as to when to re-hydrate you should be fine.  I gave up on being OCD about the hydrometer calibration and spend more time enjoying my cigars.

That Xikar hygrometer sits on my smoking porch because well, I thought is was a POS.  It gives me false readings there too

 :biggrin:

I'm not a nerd by any means. My tags work good for me though. Stop mind fukking it and have a smoke. It's not like you're splitting atoms here.

QuoteTed - 2/9/2016  5:25 PM  It's not my fault some nerd here posted about these wireless tags and made me by some. Graphs are like blinky lights. I can't top looking and tweaking.  :biggrin:

:lmao:  :lmao:  :lmao:  

 

QuoteTed - 2/9/2016  6:25 PM

It's not my fault some nerd here posted about these wireless tags and made me by some. Graphs are like blinky lights. I can't top looking and tweaking.
 :biggrin:

 :lmao:  :lmao:  :lmao:

At the end of the day, my cigars smoke fine, even using those cheap hygrometers :biggrin:

QuoteTed - 2/9/2016  3:23 PM

I see the salt test being touted as the best method all over the place, interesting to see a contradictory perspective.

I think that it comes down to the old methodology of  "That's how we always did it"

I think the salt method is a PITA, so I'll just stick with the easy method!

E

I've only used Boveda calibration and that has worked for me.  But I can't say anything about the salt test, given that I haven't tried it myself.

QuoteThinBlueLine - 2/9/2016  4:53 PM  I'm not a nerd by any means. My tags work good for me though. Stop mind fukking it and have a smoke. It's not like you're splitting atoms here.

:lmao:  

Pshaw! Splitting atoms is child play! I'd like to see Oppenheimer get three levels of his tower humidor within 1.0% RH!

 

QuoteThinBlueLine - 2/9/2016  5:53 PM

Stop mind fukking it and have a smoke. It's not like you're splitting atoms here.

No shyt!  :thumbsup:

I've been using the salt method, but I think I'll give the Boveda a try.  Although, my cigars are smoke fine so the humidly must be close.

Don't trust the salt method myself. I prefer the Boveda packs. But to each their own in this hobby.