More about humidity and gauges!

[mm]

More about humidity!

I'm the one in Baltimore with no humidifier.

I finally got a humidity gauge, digital, and it started out at 66F and

24%

It varied a trifle and then i took it upstairs, where after a few hours it is up to 70F and Lo% Lo means it's lower than 20. But I'll bet not much**. (It reads only from 20 to 90%.)

I had found a really nice gauge/thermometer, with max and min even, on Amazon, Cheney brand, for 13 dollars and eligible for free plus-$25 shipping. But a couple days later it was listed as out of stock. Other places were more expensive. A couple days after that, it wasn't listed as available from Amazon at all, only other places, and a couple days after that they were up to 26 dollars with shipping. Too much for me.

Today I was at Harbor Freight and they had one for 10 dollars, 4x4", bigger than I wanted (The Cheney is 2 1/2 x 3) but with all the same features, including min/max, F/C, a clock and alarm clock, and measures temp in tenths of a degree, although it only claims one degree of accuracy. You should note that when I had done google-shopping, the model didn't show up at all by any vendor, still doesn't, and when I googled, if it was there it was so far down I didn't see it. Searching in Harborfreight.com doesn't' find it under humidity gauge but does under hygrometer!

far, 8 hours, it seems to work.

Went back to google shopping and looked for hygrometer. Found the one I originally wanted cheaper but out of stock at 2 places. :) And some more expensive fancier ones, like

blue inexpensive one still found no place that sold one I just got at HarborFreight.

Even google-shopping on one stop gardens hygrometer didn't find it, and googling on one stop gardens hygrometer got only one hit, the harborfreight page above, quoting the reviews, which you might want to read, especially about the "salt calibration test", and the third review where the person didn't know what a "time stamp" is.

For example

it seems you can tell how humid it is by the way your cigar smokes. Most of the pages on the salt cal. test are from cigar companies. This website is BETTER:

**(BTW I think the mere fact that it's a little hotter here means the % RH would go down a trifle even with the same humidity, since warm air would hold more humidity if it were available.)

[Caesar Romano]

On Sun, 23 Jan 2011 21:03:25 -0500, mm wrote Re More about humidity and gauges!:

Thanks for the update.

[N8N]

Just FYI I got some of the dial type "cigar humidor" hygrometers from Amazon, just stuck them to the wall in various places around the house a few years ago. Did the salt calibration with them and all were pretty close right out of the box, and cheap too.

nate

[Mark]

what is the "salt calibration"?

I have 2 dial hygrometers and 1 digital. It looks like they all have a hard time reading low levels below 30% or so.

The digital one reads in 5% steps below 35% i.e. it can read 35%, 30%,

25% 20%... I have never seen it go below 20%.

Above 35% it reads in 1% steps.

Mark

[N8N]

here's one link

basically, a closed container with some damp salt in it will stabilize at exactly 75% RH at typical room temperatures, so that is typically used as a calibration point. If you need precise measurements at low humidity that won't help you much, but if within a few % is OK, the salt calibration is quick cheap and easy.

nate

[mm]

giyf.

Like I say, the one I bought just says Lo below 20, and won't go above

90 either.

Right. It would be great to be able to also check 20 and 50 percent, but no one has found a similar way to do that.

[Mark]

interesting....

thank you

Mark

[Mark]

and this

[mm]

Hey, this is great. It gives a little more explanation -- I'm still trying to understand why this works -- and it tells how to calibrate

33%. Do you have any manganese chloride I could borrow?

Although it does sound like this guy spends too much of his time calibrating hygrometers! :-)

[mm]

And he says to use pure salt. There isn't much iodine in iodized salt, but what other impurity could he thinking of, garlic salt?

Why does he recommend Morton canning salt? Who cans. I'd rather buy some non-iodized table salt. It takes me a year to use up a 24 oz. of that. Probably take you guys 4 years if you live alone, but if you eat fish, you get iodine there.

He says Magnesium Chloride Hexahydrate is not that expensive on ebay, but the only auction for the flakes that he uses is 60 dollars for 10 pounds. Like I say, he must spend a lot of time of his spare time calibratinng hygrometers. I know, I shouldn't make fun of a guy who gives all this info to needy people. YOu can also buy 100 tablets of Magnesium Chloride, which apparently people take a so-called nutritional supplement! I don't know how much that weighs, not much I guess, but it's only 20 dollars.

Better to buy 500 g of Magnesium Chloride Hexahydrate for 30 dollars.

[J Burns]

Why not go to Ace Hardware and buy 20 pounds for $17?

I prefer using an indoor-outdoor thermometer, a wick of polypropylene cord, and a 2-ounce bottle for wet-bulb/dry-bulb measurements. At room temperature, each degree of depression is about 4% down from 100%. It's most accurate using a fan and an aluminum-foil shield to keep infrared from warming the wet bulb.