Salt Test

Noah0504

As part of a late Christmas gift to myself, I picked up a Xikar PuroTemp digital hygrometer.  This one happens to be the wireless system with the base and remote sensor.

It seems that Xikar stopped selling digital hygrometers that could be calibrated sometime ago, claiming that every hygrometer they sell is calibrated at the factory.  Of course, anyone can claim anything, so I thought I would run this particular hygrometer through the salt test to see how accurate it actually was, and that's when I discovered that the salt test shouldn't ever be the final answer.

I initially used a quart size resealable bag and a shot glass filled with the salt and water solution.  After leaving it overnight, the rH reading was only 59%.  My first reaction was that I just wasted precious cigar money on a piece of junk, but then figured there was no way it could be that off.  So, I went at it again.

For my second test, I used a bottle cap to hold the solution and the same resealable bag.  Immediately, the reading began to rise and then settled to 68% after several hours.  Now I was getting closer and decided to try again using a GladWare container and went back to the shot glass.

Once again, the reading began to climb and settled to about 71%.  I kept retrying the test with different containers,different salt and water amounts and finally got my highest reading of 73%.

I'm currently doing the test one last time with a container the seals much better than what I previously used.  It's currently at %71 after about 30 minutes, so we'll see what happens after several more hours.

I write all of this to point out that the salt test can give very different results, and should probably be attempted several times before deciding how accurate your hygrometer is.  I'm considering ordering one of the hygrometer calibration kits from Boveda to see what kind of result I get there, but right now I'm fairly certain my hygrometer is at least accurate to within 2% -- which I cannot say about my analog one.

I'd also like to reference this video from Xikar where they mention the exact problems I mention above: https://www.youtube.com/watch?v=zkw4fTNoL90

avengethis

Well it should be mostly salt with just enough water to moisten the salt. You should not have standing water. I'm guessing you might have to much water.

Noah0504

I think the first time I had too much water without realizing it, but after that, I think it was bag and then maybe even the container I chose.

If you watch the video, one of the reasons Xikar gives for not offering hygrometers that can be calibrated is because of variables that can occur when calibrating with methods such as the salt test.  If it is not done properly and someone incorrectly assumes that it's just not calibrated and then does so, they'll have a false reading moving forward.  So, it's to protect the end user, however, we have to take their word that they're really calibrated.

jlmarta

There should be just enough water to make a paste of the salt. The second thing is the test should run 24 to 36 hours. It's not a 10 minute deal... Done correctly, the salt/water mixture should produce 75.5% RH. Ask any science teacher.... 

peter4jc

I've done the salt test, and agree with what was said regarding the amount of water.  But for the cost of the Boveda kit, I'd rather go that route and take the guesswork out of it.

Noah0504

peter4jc said:

But for the cost of the Boveda kit, I'd rather go that route and take the guesswork out of it.

That's exactly why I think I'll end up picking one up.  It's funny to think you could Google for hours and hours and find all of the information you could ever hope to find on calibrating with the salt test and the science behind it, but no real suggested ratio for salt and water.