Guide: How to salt test / calibrate your hygrometer

[broblues]

Don't know if its just me but Rod may want to add a note to the directions on the How To List. For if your battery is more than 1 year old start by changing the battery then continue with the Salt Test!

While not directly related to the problem you were having here's an issue I was having until recently.

I use Xikar hygrometers and calibrated them as soon as I got them. Before I started using beads for humidification I was struggling with the damn floral foam system. Needless to say, I started to doubt the accuracy of my already calibrated hygrometer and decided to re-test them. The problem is, if you've already calibrated a Xikar and then re-calibrate it you'll really throw things out of whack and really not be able to get a good measurement. As it turns out, and I only found this out after re-reading the directions that came with the Xikar, if you are going to re-calibrate you should pull the battery to allow the unit to reset itself and then re-calibrate.

Absolutely the truth!!! Otherwise, lots of deviation.

I probably could have saved myself and Xikar a lot of heartburn by just re-reading the instructions before sending them back under their lifetime warranty. I will say that they took good care of me and exchanged them with no questions asked even though it ended up being user error.

I'll tell you.....both Xikar and Boveda have amazing reps. I have dealt with both extensively, and can only hope I rep my company as well as they do theirs.

 

[Cigar FF]

I just purchased 3 new Caliber III hygrometer's for a new coolidor and humidor. Can I calibrate all 3 in one shot? Will the results vary if done this way or should I just do them all separately?

 

[Rod]

Paul - I'm just now seeing your post. Did you have to adjust your Avallo at all? If so, how many degrees difference is it from 0?

 

[Tall Paul]

Paul - I'm just now seeing your post. Did you have to adjust your Avallo at all? If so, how many degrees difference is it from 0?

Rod it ended up being the hygrometer the whole time since the battery was low. Once I replaced the battery and re caled the hygromiters it fell in line with the avallo perfectly. I never had to adjust the Avallo which was great. This was back in January and we are still holding strong with them reading a point or so form each other.

 

[Techdawg2012]

I salt tested my new hygrometer last night. I did the appropiate steps (even put in a new battery to make sure). I let it sit overnight and got a 73 percent reading this morning. Should I just add 2 percent to whatever reading I get when I put it in the humidor or try something else?? Thanks

 

[broblues]

I salt tested my new hygrometer last night. I did the appropiate steps (even put in a new battery to make sure). I let it sit overnight and got a 73 percent reading this morning. Should I just add 2 percent to whatever reading I get when I put it in the humidor or try something else?? Thanks

Most are adjustable. I would adjust it up to 75% (up 2 percentage points), if it is the type that adjusts, or you will have to do the math every time you check on it.


Edit for information

 

[Techdawg2012]

I salt tested my new hygrometer last night. I did the appropiate steps (even put in a new battery to make sure). I let it sit overnight and got a 73 percent reading this morning. Should I just add 2 percent to whatever reading I get when I put it in the humidor or try something else?? Thanks

Most are adjustable. I would adjust it up to 75% (up 2 percentage points), if it is the type that adjusts, or you will have to do the math every time you check on it.


Edit for information

I would, but it doesn't have a button to adjust it.

 

[Tall Paul]

Google the hygro and see how it adjust. I should. That is the point to the salt test because the salt brings it to 75% and when you hit your re-cal button you are re-calibrating to 75%. If you can't find it post a pic of your hygro here and we will try to help you from here.

 

[Cigar FF]

Since it's not adjustable, you can either re-test and make sure you have a solid seal as any leakage could let RH escape or just note on the hygro that it is X points off from 75%. In your case, I would write -2% somewhere (maybe in pencil so it's not so perminant) so you know when you look at it or if you get another one.

I have the same issue. Mine is off by -2%. It's not a big deal so no need to go crazy. You'll be hard pressed to get perfect RH in your storage anyway.

 

[Matt Rushmore]

Are the Humidipak calibration bags ALWAYS correct when first opened? Is it normal for a digital hygro to be 7% off right out of the box? Here is why I ask....

I have a HygroSet II Digital Hygrometer in a 75.5% Humidipak calibration bag. The bag was first opened three days ago to calibrate two analog hygrometers. After the 24hrs staying at between 65 and 75 degrees the analog hygros read 66% and 69% so I calibrated them and left one in the bag for a while longer where it appeared to stay around 75%.

Yesterday I put my brand new digital hygro in the bag and it reads 68% after 24hrs of between 65 and 75 degrees (more like 65-69 degrees to be technical). I messed with taking it outside a bit ago (after the 24 hrs) and when the temp increased the RH would fluctuate about 2% but when its back in its 65 to 75 degree average temp it goes back to 68 - 69% RH.

I am kind of confused as to why the digital hygro would be that far off initially but don't know whether to question the science of the calibration bag (especially considering the analog hygros were both in the high 60% range also in the same calibration bag) or just trust the science of it, set the hygro and call it a day.

Any info from experience would be greatly appreciated.

 

[Cigar FF]

I would recommend you try either getting new batteries to rule that out or get use a jar instead of a bag. If you think it's the Humidipak, try using the table salt with distilled water in a soda cap.

 

[N8NOE]

Works Great...

 

[SkyKing]

I just purchased 3 new Caliber III hygrometer's for a new coolidor and humidor. Can I calibrate all 3 in one shot? Will the results vary if done this way or should I just do them all separately?

Bump:
 
The Caliber's should not not need calibrating. However, the quick test is to put all three together in a closed humidor or a baggy and check that the readings match each other. Even better is to compare them against a calibrated hydrometer. If they are simply a point or so off, you needn't worry.

 

[personal User]

 
Another thing you can try, is a Boveda pack. They are various combinations of various salts and their rated humidity is very accurate. For just a few bucks, you could get one and test your hygros.

Just say'n
 

I went from 70/70 to 65/65. I am using a wineador. 
 
I calibrated 3 digital hyrgometers. 
 
After changing battery in the older ones, and fooling with the salt test - which works well, I believe that while these little devices are well worth what we are paying for them, they are not linear. Meaning that if calibrated at 70 %, they are not necessarily accurate at 65 %. Also, these little guys can be difficult to set precisely.
 
FWIW, my final solution was to buy a 65% boveda pack,  put the three hygrometers in a good moisture proof transparent bag, or double bag in ziplocks, put it in the wineador for 24 hours in such a position that I could read them through the door of the cooler, with the wineador at 65 degrees.
 
The three I had calibrated at 70 degrees were off by 2 to 3 % at 65% (compared to the boveda) Also, at that setting it was difficult to adjust them precisely. Once I got them all reading the same, I quit and just noted the difference.
 
Checking the temp against a recently calibrated thermometer, they seemed quite accurate temperature wise.
 
I will note that if you look at standards for instruments that determine R/H, you will have to spend about 2,500 or more to get resolution closer than +/- 2%.
 
Boveda packs are supposed to be +/- 1%, so for several bucks you should be getting an excellent reference point.
 
I will also note that if you are storing at 70 %, the salt method is simple and extremely accurate.

 

[WindingDown]

So I bought a Xicar Purotemp (Round Digital hygrometer) and brought it home. I read the guide and various other guides on how to do the salt test. I did the test and it only got to 65% after 18-24 hours. Thinking, well, that's exactly 10% off of where its suppose to be, guess the salt test is right but this hygrometer is off. I brought it back to the B&M I bought it at and switched it out with another one because Xicar claims accuracy right out of the box within 2% +/-. Obviously doing the test and having it 10% off I wasn't going to trust the 2nd one. I put it in a ziploc with the salt/distilled water and left it for another 24 hours. Much to my dismay it again wasn't anywhere near 70% let alone 75%.
 
I've now come to 3 options for this differential.
 
1. The salt test is B.S.
2. Two hygrometers in a row are faulty.
3. The guy new to the world of cigars doing the salt test is messing up somewhere.
 
The salt test has chemistry and years of time tested practice on its side. Xicar (at least to my knowledge) is a great company with a trusted name. That leaves one option and the most likely cause of the problem.
 
I've combed through many topics/posts on here and read other sites' guides. At this point I'm considering buying a boveda calibration kit but I'd really like to refrain from spend more money than I already have just getting off the ground. 
 
I used a 2 liter cap before and this time I'm using a larger cap from a plastic Almond Milk container (about twice the size of the 2 liter). Each time I've used the same amount of salt and added distilled water to create a thick slurry/pasty consistency. Is that too much water? Should it be more solid? I'm at a loss. Any advice would be great and much appreciated even if that advice is suck it up and drop the money on the calibration kit and deal.
 
Thanks folks!

 

[personal User]

$4 solution that is easy and works.
 
Buy a boveda pack at the same RH you want to run your humidor.
 
Double bag (ziplock) the boveda pac and the hygrometer.
 
let sit 36 hours, no kidding - 36 hours or more.
 
If the xikar doesn't read what the boveda pac is -
 
say it's a 65% boveda pac and the xikar says 67.
 
Put a piece of tape on the xikar that says -2%
 
Subtract 2% from the reading.
 
Problem solved, for four bucks
 
ETA - if calibrated at 70/70 and you run at 65/65, it may be off anyhow.
 
Buy a full large $4 boveda pack, not the small calibration one. The calibration one is simply smaller and has a better bag/envelope.
 
ETA -BWahhha
 
didn't even check the post above Winding Down and notice my own post.
 
What the hell, I said it shorter and sweeter the 2nd time :laugh:

 

[cigars&coffee]

$4 solution that is easy and works.
 
Buy a boveda pack at the same RH you want to run your humidor.
 
Double bag (ziplock) the boveda pac and the hygrometer.
 
let sit 36 hours, no kidding - 36 hours or more.
 
If the xikar doesn't read what the boveda pac is -
 
say it's a 65% boveda pac and the xikar says 67.
 
Put a piece of tape on the xikar that says -2%
 
Subtract 2% from the reading.
 
Problem solved, for four bucks
 
ETA - if calibrated at 70/70 and you run at 65/65, it may be off anyhow.
 
Buy a full large $4 boveda pack, not the small calibration one. The calibration one is simply smaller and has a better bag/envelope.
 
ETA -BWahhha
 
didn't even check the post above Winding Down and notice my own post.
 
What the hell, I said it shorter and sweeter the 2nd time :laugh:

I just calibrated my hygrometers exactly as described here using a double ziplock bag for 36 hours, but I used a large 69% boveda pack (I thought I ordered a 65% pack until I opened the box) . The results were different compared to the calibration done at 75%. I'm glad to learn the hygrometers are not linear, because my RH was actually lower than what I thought based on the calibration done at 75%.  Thanks for the tip Personal User!  I will calibrate the hygrometers again once I get a 65% pack and compare the difference.  

 

[cigars&coffee]

Both xikar and acurite were 69% RH after calibration.  Now there is a 4% difference between the two after being in the coolidor.  The are side by side and the coolidor is full, and I don't know which one is accurate.  Anyone have suggestions or ideas? 

 

[personal User]

Both xikar and acurite were 69% RH after calibration.

Temperature is relative here, also. To be as close of possible, they need to be calibrated at the temperature they are going to be used at.
 
If they were calibrated at a different temperature than the coolidor, I suggest recalibrating in the coolidor.
 
If the temperature is the same as when the units were calibrated, I would make a reasonable assumption that the average % of the two is a reasonable approximation of the RH.
 
Given that the accuracy within that price range of instrument is  +/-  2% as a standard spec, and probably more like 3% - half the difference is a reasonable assumption - and 4% total variation between 2 units would not be uncommon and would not be out of specification.
 
I'm guessing that if you recalibrate them with them in the coolidor you will get readings that are more similar, or who knows, you may not.
 
ETA - or a battery on one may be starting go.
ETAA - don't forget, these are essentially $20 units that probably have $2 worth of parts in them. They are nowhere near lab quality instruments even though they work great for our uses within the price range that is acceptable for this purpose.

 

[cigars&coffee]

They were calibrated at the same time along with a few others and each had new batteries.  They have adjusted against since being in the coolidor and now only have 1% difference.  Thanks again for the advice and next time I will calibrate in the coolidor and note any differences. I feel much better knowing the RH is closer to being accurate than not.