Salt testing a digital hygrometer

[wilmotrogers]

I have heard analog hygros being off a large amount, but after I salt tested my digital hygrometer, it only reached 58% RH. I even replaced the battery and did it again (ziploc bag, wet sand in a teaspoon measuring cup). Can the hyrgrometer possibly be off 17 points?

I am giving serious thought to scrapping it and buying another one.

Just wanted to get your thoughts.

 

[mr.mac]

I would try double bagging the "experiment". For me, one ziplock bag didn't hold as air tight as two. In fact, I would consider moving the experiment to one of those lock and seal tupperware containers. Once I did that, I started getting much more accurate readings on my hygros. By the way, how long did you give the hygos in the salt test? I had some hygros that took over 24 hours to fully reach their final reading. Consider keeping them there for a couple of days...

My .02 cents...

mac

 

[viper139]

....ziploc bag, wet sand in a teaspoon measuring cup....

I am hoping that the "wet sand" in your post is a typo and you meant to say salt.

No matter what method you use to check the accuracy of your hygrometer, either the salt test or the Boveda Calibration Kit, give the test at least 36 hours. It takes longethan you thionk for the atmosphere inside the bag to stabilize.

 

[beatnik]

I am hoping that the "wet sand" in your post is a typo and you meant to say salt.

No matter what method you use to check the accuracy of your hygrometer, either the salt test or the Boveda Calibration Kit, give the test at least 36 hours. It takes longethan you thionk for the atmosphere inside the bag to stabilize.

I agree and i have one that is off terribly I rarely use it but it is only off by 6% actually thats not terrible as it is common to be 3%-5% off but actually 58 might be right for water and sand........ if you are not sure how to do this the boveda kit will help a lot I got a couple digitals that are adjustable and i will never buy another that s not nor will i buy another spring analogue hair is better than digital sometimes.

 

[wilmotrogers]

It is water and salt. Not sure where my head was at.

 

[chainer]

Oh snap, your using an electric with 17% off? Nevermind. Ya, I'll echo everyone else. Try to re-do it with a Boveda Calibration Kit. Mine was only off 3%.

 

[BlindedByScience]

In order for the wet salt to drive the RH of the environment, it has to be really sealed off. I've found that one ziploc bag won't do it. Double bag the test environment, or better yet, use a mayonnaise or mason jar with a screw on lid and a good seal. Weather it's salt or a Bovida cal kit, this is what has always worked best for me, and is very repeatable. As I said, one bag usually won't work adequately.

Then, wait 24 hours which I've found is the best elapsed time to wait. If you use a jar and wait 24 hrs, you'll get repeatable, solid results.

Good luck - B.B.S.

 

[wilmotrogers]

Been about 4 hours, and I am up to 63%. I double bagged it, and put it in a tupperware container. I will see where I stand in another 24 hours. Thanks for the suggestions guys.