Harvest & Curing At LEAST one of these hygrometers is wrong.

[NoviceProfessor]

I've had the bigger square one for a while. But I just got the 4 pack of little round ones in the mail this morning. I've had them all in the same space for 12 hours. Obvious inconsistencies. Already emailed the seller. Waiting for response.
Frustrated.

 

[NoviceProfessor]

Let me see if this pic works better...

 

[bushmasterar15]

Some hygrometers can be calibrated or adjusted. But you can do the salt test and then put what the + or - is so you will know what the actual reading is.
Salt test 'em bud!!

With Winter here, the cool, crisp conditions have likely altered the environment inside your humidor. So, you'll want to keep a close eye on your humidor. But how do you know that your hygrometer is reading the humidity accurately? A simple calibration will do the trick. Here are a couple of ways to calibrate your hygrometer:

1. The Towel Test:
   Dampen a towel (not dripping wet, but good and damp), then wrap the hygrometer in the towel for 30 to 45 minutes. Then unwrap it and read the humidity (quickly). If your hygrometer is perfectly calibrated (few are) it will be reading exactly 100% humidity. Most likely, it will be reading somewhere between 80 and 90%. At this point, whatever the hygrometer reads, you can either set the needle to exactly 100% immediately after the test, or if you're a little lazier, make a mental note of how far over or under the actual humidity is from the reading from your hygrometer.
2. Wanna get a little more technical? Try the Salt Test:
   Luckily, as nature would have it, when salt and water (NaCl and H2O for you studious types), are in a saturated solution at equilibrium, the resultant humidity is 75%. This gives a fantastic reference point to calibrate our hygrometer. There is an easy way to determine if your hygrometer is accurate. Here's the procedure you should use: you need a ziploc bag, a screw-on beer bottle cap (or other small container) a small amount of salt (regular 'ole table salt), and water.
   1. Place the salt in the bottle cap (or other small container).
   2. Dampen the salt with water. Do not put so much in that the salt gets "sloppy". You want a damp pile of salt in the bottle cap.
   3. Place both the hygrometer and the bottle cap full of damp salt in the ziploc bag and seal it well. (It is important not to let air on or out while the test is going on.)
   4. Keep it like this for over 8 hours.
   After 8 hours in the damp salt environment, the actual humidity inside the bag will be 75%. Compare it to your hygrometer, your hygrometer should also read 75%. If not, you will then know exactly how far off your hygrometer is. If it's off, note the amount and direction that it actually reads and be sure to add or subtract that amount when reading the hygrometer. If the hygrometer has a control to adjust it (either the needle or the display), you can set the hygrometer to 75% immediately after the test.
   
   You should salt test your hygrometer every 6 months or so to be sure of the accuracy.

 

[Mañ'O'Green]

@NoviceProfessor I have 15 or so little cheap (EBay $1.50) hygrometers; only about half of them are in agreement. So here is what I did. Boveda makes a hygrometer calibration kit. I got one and calibrated 2 more expensive instruments. Then I put them all in a jar overnight. I marked a piece of paper with a number line from -5 to +5. The two calibrated tools were placed at zero. working quickly I sorted the cheapos where they fit. If they were more than 5% off I threw them away. Then using marking paint green for plus orange for minus I put a dot on each one for how many % they were off so if one read 3% higher than the 0 mark group I put 3 green dots on it. If it was 1% lower 1 orange dot. Now when they are in the curing jars it is easy to just add or subtract to get to the actual humidity. It sounds more complicated than it is.

 

[NoviceProfessor]

Thanks guys. I don't think these have a needle or anywhere to change settings for calibration. I can definitely use the methods you've described to figure out how far off they are. I really want to be precise. The one that has consistently been 13-16% below the others might just get thrown out.
Thanks again!

 

[Banjacked]

@bushmasterar15

Great advice, never heard of that test before

 

[Banjacked]

Thanks guys. I don't think these have a needle or anywhere to change settings for calibration. I can definitely use the methods you've described to figure out how far off they are. I really want to be precise. The one that has consistently been 13-16% below the others might just get thrown out.
Thanks again!

I have two of these things, they eat batteries like crazy, but I'll pull one apart to see if they can be adjusted.

Give me a few minutes, will let you know and take piccies IF they can


Edit: No adjustment possible

 

[bushmasterar15]

@bushmasterar15

Great advice, never heard of that test before

It was posted my @912GreenSkell that I seen so copied that post to here and how I checked the ones I have.

 

[Banjacked]

Don't matter where the original came from, I, for one, can't read every single post on the forum so I'll always give credit for passing on info irrespective of the source.

 

[bushmasterar15]

@NoviceProfessor I removed the other duplicate thread and added the picture to your first post.