Hygrometer Calibration FAIL.

[TonK]

I've calibrated my hygrometer before, like a month ago using the salt test.

Now I want to re-calibrate the one and calibrate my new unit.

Did the salt test last night using a slush mix of salt in medicine dispenser caps.

The readings were waaaay off on both.

Like 14 points.

When I calibrated the one a month ago, it ended up at 71% - so that's what I went off of.

It's now sitting at 62% after 5 hours.

I don't get it.

I used table salt, distilled water and a ziplock bag.

Am I missing a step?

Is this normal?

The other one reads 65%

I just filled a water bottle cap to near the top with salt, put a few drops of distilled water on it to dampen it.

Is that the right way?

I don't see how these can be so far off.

 

[B.HOBS]

A few things....

Freezer bags. Doubled up. No zipper, only press close. Not sure which you're using, but this is important. It will give you a better vapor barrier.

Second, give it some time. I recommend you leave it overnight, or 24 hrs, with the above setup. If its still off at that point, then your units are genuinely off.

Good luck!

ETA: Temp will also affect your readings, so keep the temp consistent.

 

[TonK]

Thanks bud.

I think I got em set right.

 

[TonK]

No, I didn't get them right last night. So I used a Tupperware container, and recalibrated. Got my 71% reading back.

Thanks again man!

 

[BlindedByScience]

Next time, try a mason jar or an old mayo jar....someting like that. I always get better results using a jar than any bag....

 

[TonK]

Next time, try a mason jar or an old mayo jar....someting like that. I always get better results using a jar than any bag....

I'll try that, thanks for the tip.

 

[broblues]

When ever you recalibrate, its a good idea to remove the battery (if digital) and reinsert. I've had problems when I didn't. (and it's recommended by the manufacturer (Xikar))

 

[TonK]

When ever you recalibrate, its a good idea to remove the battery (if digital) and reinsert. I've had problems when I didn't. (and it's recommended by the manufacturer (Xikar))

I actually did that on both.

Excellent tip though, thanks for sharing.

 

[Chemyst]

A slush is too wet.
More like moistened grains of salt is right.

Add grains of dry salt, until they soak up
the excess water of the slurry, but all grains
are moist. It should look like wet sand at
the beach, with no extra water.

I did one of mine yesterday, and the other is in
a zip lock now. The HygroSet was very accurate
at 74% (supposed to be 75%), but the Don Salvatore,
that I'm doing now, always reads 7-8% too high.
I also let them sit for 24 hrs., so they stabilize in the
zip lock.

Never any real problems.

Chemyst

 

[Acclaym]

This is probably a stupid question fellas, I apologize, but what is your method for calibration using a jar/tupperware?
I always used a bag so I could push the calibrate button while it was still in the humid environment. I felt like the reading would change before I could calibrate when I used tupperware...
Do you take your hygrometer out, calibrate, and repeat to make sure its on?

 

[Chemyst]

The HygroSet has an adjustment wheel on it, but for 1% (1 click)
I won't bother.

I just keep a mental note of how far off the other hygro is. Right
now it reads 8% high, compared to the 75% standard. I may write
"reads 8% high" on a small paper and tape it to the hygrometer.

Chemyst

 

[vortex]

The HygroSet has an adjustment wheel on it, but for 1% (1 click)
I won't bother.

I just keep a mental note of how far off the other hygro is. Right
now it reads 8% high, compared to the 75% standard. I may write
"reads 8% high" on a small paper and tape it to the hygrometer.

Chemyst

I do something similar. I write the salt test number on the hygro. You want the test temp near the operating temp of your humi, too.