Salt Test - 83%

[NapaNolan]

My hygrometer went wonky all of the sudden so I wanted to salt test it...just a few hours after starting the test it's at 83%.

It's a cheap hygro that came with the humidor and I cannot calibrate it.

I'll be getting a new hygro soon, but in the mean time, if the RH does not change, does this mean I should just subtract 8% from the displayed RH to know what it truly is or is the hygro completely unreliable?

[wolfain]

Yes that's correct but I'd suggest you get a better hygrometer asap , an adjustable one, and btw the salt test isn't entirely very accurate.

I would suggest the boveda calibration unit, (it's really just a 75RH boveda and a ziplock) but it's accurate.

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[Scrubber]

The analogue one that come with my humidor was about 10% off following the boveda calibration kit. It then just got stuck on 50% and I can't adjust it anyway. It looks good though.

Caliber IV digital is spot on since I've had it.

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[Fugu]

We just had the discussion in this thread the other day.

..., and btw the salt test isn't entirely very accurate.

This statement just isn’t correct. The salt test still is as accurate or even better to Boveda use – same physicochemical principle.

However, one needs to observe that the test is done correctly:

First, really make sure that you get a (over-) saturated solution. For this you will need about 36 g NaCl per 100 ml water. Use at least 45 g and you’ll be fine. But make sure that everything is properly dissolved before starting the test. Stir it long enough, and perhaps even use warm water for preparation, let cool down to room temperature afterwards. There must be a large enough undissolved bottom sediment remaining.

Then, second most important point to make sure is that you keep the temperature absolutely stable during testing. A one-degree change around 20 °C will bring the test atmosphere out of equilibrium (a ca 0.7 g / m3 absolute change in max. atmospheric water capacity at 75 % rH), and can cause a corresponding 3-4 (!) percentage point instantaneous reading error in your hygrometer. The temperature effect very often is underestimated.

I regularly use a larger Tupper bowl with the bottom completely covered with the prepared salt solution, and put my hygros on top of a flipped cup inside that bowl. Close the top with saran wrap and seal with a rubber band. Using that setup, I usually attain stability within less than 4 hours.

The deviation of up to 8%, you are reporting, may be a real instrument error. But if this was the first time you doing it, I’d suggest properly re-checking your setup.

Another hint – I have learned that in America, there are some dietetic table salts in use, where a larger proportion of potassium replaces sodium. Using such a salt would result in wrong readings! Preferably, a pure NaCl-salt should be used, which would give 75.5% rH @ 20°C.

Good luck!

Paul

[CUBANO]

Good info , Paul. thanks!

[Fugu]

The analogue one that come with my humidor was about 10% off following the boveda calibration kit. It then just got stuck on 50% and I can't adjust it anyway. It looks good though.

Caliber IV digital is spot on since I've had it.

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"It then just got stuck on 50%"

Analogue ones (fibre-tension type) need being regenerated from time to time. The fibres need being "reloaded" with water to maintain their tension properties. However, if you can't set it, it isn't worth the effort anyway.

[NapaNolan]

This morning it's reading at 77%, guess it's closer than I originally feared.

[Fugu]

This morning it's reading at 77%, guess it's closer than I originally feared.

Sounds good, can't get much better.

I bet, was either an issue with lacking temp stability or the salt had't yet been fully dissolved.

[mcease022]

Sounds good, can't get much better.

I bet, was either an issue with lacking temp stability or the salt had't yet been fully dissolved.

yup sounds like the case. I'd use a boveda to be sure. Also, some cheap hygros dont respond fast enough. I have 2 Caliber IV and they are miles ahead of the 2 cheapies I have. The other two are ok for humidity, but dont respond fast.

[fookite]

We just had the discussion in this thread the other day.

This statement just isn’t correct. The salt test still is as accurate or even better to Boveda use – same physicochemical principle.

Sure, the salt test is accurate. The problem is, the further away from 75% rh you store your cigars, the less meaningful it is to know when your hygrometer is reading 75% rh.

[NapaNolan]

Broke down and ordered some 62% Boveda. I don't trust this hygrometer at all. Will test it with a pack before I toss it.

I found some mold recently but ambient rh has been in the mid-upper 60s lately so I haven't been able to lower the humidity in the humidor at all.

Any other ideas for lowering humidity if I don't like the Boveda?