Hi,

I'm doing the salt test on my digital hygro and its quite slow. My cap of humid salt has been in the ziplock for more than 12 hours and my hygro reads 65. He is getting about 1% per hour.

Is it normal that its slow like that ? or it is my hygro that is not working properly ?

I've used about 1 teaspoon of salt, added a bit of water. Putted these in a small sandwiched sized ziplock and doubled the ziplock with another of the same size.

Any thoughts ?

Thanks
Fred

Yes, it's working properly.

Just as Boveda recommends with their cal kit, let the test run for 24-36 hours.

Yeah, thats what I was planning on doing. I was just afraid my hygro was too slow.

Thanks
Fred

Does seam to be taking a long time.

Give it the 24 hours and then tell us what it reads. It is possible that the hygro is that much off also.

Yeah, it's still at 65. It's been there the last 6 hours. It is possible the hygro is off that amount. I will give it the rest of the day and we'll see. I may try to get another hygro and do the test. I'll keep the best of the two and return the other !

Thanks
Fred

Let us consider the hygrometer salt test.

A modern electronic thermo-hygrometer of good quality is expected to have a temperature compensation circuit.
Thus if its humidity sensors respond differently to humidity at different temperatures it is expected that its electronic circuitry would compensate for this, knowing the temperature from its temperature sensor and knowing the response of its humidity sensor at different temperatures.


As for that famous salt test. This salt test will have a different relative humidity depending upon temperature. The salt-humidity-air equilibrium changes with temperature.
So...the salt test must be done at a specific temperature to give that famous 75% RH...right?

Between 0 C (32F) freezing and 80 C (176 F) the %RH it varies from 74.4% to 76.3%.
At 20 c (68 F) it is 75.5%
At 25 C (77) it is 75.3%

It is very stable for table salt (sodium chloride, NaCl).

U can assume 75% RH at any temperature that you are wallowing in.

Have u had enuff? I have.



salt air humidity equilibrium http://www.omega.com/temperature/Z/pdf/z103.pdf
NaCl is 75 +/-1% rh for a wide temertaure range

Yeah QM, I have already read that stuff on another of your post. Quite interesting.

Thanks
Fred

I bought my thermo-hygrometers at La Source formally Radio Shack. I have four or five of them. Had two of them at work professionally tested and approved.

nexxtech

I've seen hygros read as-much-as 10% low doing a cal test. And one that was 10% low, the manufacturer said it's accuracy was +/-1%.

lol QM I just got back from the shopping mall and bought one at Canadian Tire. I passed by The Source and didn't enter !

I'll check the one I have and maybe go check the one you are talking about. It seems great and cheap.

Fred

btw what happens if I'm not using distilled water to do the salt test ? I didn't had any when doing the first test.

The test I'm starting now on the other hygro will be with the distilled water.

Thanks
Fred

Using the salt test or using the calibration kit, you should let it sit for at least 3 days. I did my calibration over the course of 2 weeks. I'm pretty confident about my readings now....

By the way. The salt test exposes the sensitive electronics and sensors to corrosive salt. Careful.

Do you already have a humidor set up with cigars in it?

No I don't have any humidor. I'm getting a small coolerdor ready cause I want to bring back some cigars from Cuba (I leave May 4th).

As for my salt tests. The one started yesterday at 5pm is now at 67% RH. It got 1% during the day...

The other one that I started at 5pm today is now at 54% RH. I will wait until tomorrow to compare them.

I don't plan on leaving them a whole week. By the way the RH readings evolves, I don't think it would make big difference.

Fred

24 hours should give you a good reading. I have one that is 7% off. You just have to remember what number it is off by and then add that to the number that it is reading in the humidor.

After 12 hours, the second hygo as stabalize at 61% RH. Its 6% lower than the other one. It may get 1 or 2% but no more than that.

I wonder if there is something I'm not doing ok since both of the hygro tested are greatly under what they should be.

Fred

I tried to move them a bit and RH reading went up in both cases. Maybe I was obstructing the RH sensor by the way they were lying in the ziplock.

I will let them stabalize a bit longer.

Fred

Just buy the calibration kit.Using salt is like still reading by candle light.