Accurate Hygrometer

[Mike Guilbault]

Does anyone have a recommendation for an accurate Hygrometer?  With the cold we've been experiencing here in Ontario lately, my humidity is way too low for printing - between 16 & 23%.  I have two hygrometers - just the cheap digital kind - and they're about 8-10 percentage points off from each other so I don't know which one is more accurate.  I suspect neither of them are.  Seems the more accurate ones I'm finding online are designed for humidors, so not sure if they'd be suitable for a print-shop situation.  The room I print in is about 650 sq ft and the printers are close to some large windows which I'm sure are contributing to the low humidity.  But I need to start with a more accurate reading. So I'm looking for a decent hygrometer. 

[Landscapes]

Does anyone have a recommendation for an accurate Hygrometer?  With the cold we've been experiencing here in Ontario lately, my humidity is way too low for printing - between 16 & 23%.  I have two hygrometers - just the cheap digital kind - and they're about 8-10 percentage points off from each other so I don't know which one is more accurate.  I suspect neither of them are.  Seems the more accurate ones I'm finding online are designed for humidors, so not sure if they'd be suitable for a print-shop situation.  The room I print in is about 650 sq ft and the printers are close to some large windows which I'm sure are contributing to the low humidity.  But I need to start with a more accurate reading. So I'm looking for a decent hygrometer. 

I bought this one here Mike.

http://www.amazon.ca/CiGuru-CH003-Adjustable-Analog-Hygrometer/dp/B00GEKWP0S/ref=sr_1_6?ie=UTF8&qid=1424237399&sr=8-6&keywords=hygrometer+analog

Mine came with a crack in the plastic cover, but just off to the side.  Its really not all that adjustable I would say given that you can't really get a screwdriver into the little slot that you are supposed to turn to adjust it.  But the reason why I went with analog is because I think it gives a more pure reading than digital.  I can always mentally adjust the number.  I did the test with putting it in a bag with some wet salt, saw how close I got to 75% which is what the number should be, and then just make a mental note.  My iPF printer also tells me what it thinks the humidity is when I make a print, so I keep all of these values in my head and just subtract.

From what I read, this one here should be fairly accurate, but i think its too expensive

http://www.amazon.ca/Quality-Importers-HygroSet-Hygrometer-Humidors/dp/B000H6CZQE

I have my printer in a small den, so when I turn on the humidifier and run it all night, I can easily get it to 60% from a starting of 20-30%.  This tells me that at least my hygrometer is working (and so is my humidifier! LOL).  In fact, what I need to do now is buy one of those outlet timers that will let me turn the humidifier on and off every 15 mins to keep it at 40-50%.

So in conclusion, the hygrometer is off by about 10%, but since I know this, I can always just add.  It seems to move nicely with the weather, so at least I know its giving me good data in terms of the difference in humidity, even if the number isn't accurate.

[Bart_van_der_Wolf]

So I'm looking for a decent hygrometer.  

Hi Mike,

Most hygrometers drift over time, and need recalibration. So whatever you wind up with, make sure it's user adjustable if you want it to be accurate. I suppose availability of such equipment and the materials for calibration, varies locally, unless there is a reputable global seller available on-line (e.g. serious equipment like from Greisinger may be available here, or this one). I don't know if they ship to Canada.

Alternatively, you know that the relative humidity drops if you heat up the air. So anytime heating is in play, you need a source for natural evaporation which will to find its equilibrium more or less automatically (assuming outside humidity is not too low either). I use such natural evaporation devices myself and they work great, if their capacity is providing enough surface area to give off water to whatever the air requires. Other devices that actively evaporate need controls like hygrometers, these natural evaporator devices cannot over humidify (the higher the humidity, the lower the evaporation, it's an equilibrium in a stable temperature environment).

Cheers,
Bart

[Jager]

Between his Cone Editions Press and Inkjetmall/Piezography businesses, Jon Cone manages a pretty extensive suite of printing equipment.  He recommended this relatively inexpensive hygrometer http://www.amazon.com/gp/product/B00JXOKQVW/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Seems accurate, from everything I can tell.

[Bart_van_der_Wolf]

Between his Cone Editions Press and Inkjetmall/Piezography businesses, Jon Cone manages a pretty extensive suite of printing equipment.  He recommended this relatively inexpensive hygrometer http://www.amazon.com/gp/product/B00JXOKQVW/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Seems accurate, from everything I can tell.

Yes, looks affordable enough to try, and it can be user calibrated. Don't know how accurate its temperature reading is, which is part of the info required to do an accurate calibration, and if that can also be calibrated.

Cheers,
Bart

[Mike Guilbault]

I saw the Caliber IV, but it designed for humidors so wasn't sure if it would be suitable for a 650 sq ft. room.  Of course I can place it by the printers which should get me a reading for that immediate area. And if Jon cone recommends this, I'm sure it should do the job.

 I also found this one, which is more expensive, but also should be more accurate.  http://www.ambientweather.com/fikf122pmh.html or this one which is considered 'Laboratory Grade': http://www.ambientweather.com/fi12501.html

[howardm]

Mike,  take a look at these........

http://thermoworks.com/products/humidity/

(and if you like cooking/BBQ, the Thermapen is simply the BEST!!!!!!!!!!!)

[Bart_van_der_Wolf]

I saw the Caliber IV, but it designed for humidors so wasn't sure if it would be suitable for a 650 sq ft. room.  Of course I can place it by the printers which should get me a reading for that immediate area. And if Jon cone recommends this, I'm sure it should do the job.

 I also found this one, which is more expensive, but also should be more accurate.  http://www.ambientweather.com/fikf122pmh.html or this one which is considered 'Laboratory Grade': http://www.ambientweather.com/fi12501.html

Hi Mike,

I'm not sure about the inner workings of the 'Fisher's, but hair hygrometers are harder to calibrate for differing temperatures. An electronic hygrometer can automatically adjust its RH values for the current ambient temperature (within the accuracy of its thermometer function), and sometimes for barometric pressure.

Of course, if you keep the room temperature constant, then there is no real measurement preference for either solution. If their synthetic hair is really maintenance free, not having to use a battery is a benefit.

Cheers,
Bart

[MHMG]

Here's a nice low cost one I have used with very good results:

http://www.amazon.com/Quality-Importers-HygroSet-Hygrometer-Humidors/dp/B000H6CZQE/ref=sr_1_2?ie=UTF8&qid=1424273020&sr=8-2&keywords=digital+hygrometer

Don't let the fact that many like this one are designed for humidors. It's not relevant. All the low cost digital hygrometers like this rely on capacitive polymer type sensors, so there are limits to accuracy and reading stabilization time on the low and high ends, but this one appears to work well enough down to about 20%. Below 20% precise readings tend to stall, but nonetheless it will alert you to the fact that your print studio is indeed mighty dry!

Sling psychrometers can be used to provide more accurate readings in dry conditions and to serve as a reasonable (and low-cost) way to calibrate your low cost digital hygrometer for those very dry conditions: They work by comparing the difference in readings between two thermometers, one dry and one with a wet sock covering the bulb. Easy and reasonably accurate but slow to use.
http://www.amazon.com/Bacharach-0012-7012-Spirit-Filled-Psychrometer/dp/B000LDNH8I/ref=sr_1_1?ie=UTF8&qid=1424275793&sr=8-1&keywords=sling+psychrometer



I actually prefer to use dataloggers like this one to keep track of various locations in my historic home on an ongoing basis, including my print studio.

http://www.onsetcomp.com/products/data-loggers/MX1101

Not super cheap, but reasonably priced for what they can do and factory calibrated to within + or - 2%RH over a 10-90% RH range. This one uploads the data via blue tooth to a smartphone or tablet. It is programmable, and I set it to continuously record about three months worth of temp and RH readings in five minute intervals. Later, I upload those records to Excel where I can generate annual records and evaluate ongoing conditions for both storage and display areas here at the Aardenburg Archives. While my environmental monitoring requirements undoubtedly go beyond that of a typical printmaking studio, the price of this instrumentation and its ease of use makes it worthwhile for anyone wishing to track seasonal indoor variations in temperature and humidity which over time can effect the quality of artwork, antiques, musical instruments, humidity sensitive equipment like wide format printers, and even one's expensive stash of cigars


Lastly, chilled mirror Hygrometers are the ultimate choice in accuracy and reliability. Typically traceable to NIST standards, but definitely expensive, so I won't recommend a particular model. Total overkill for what printmakers need to monitor their environment, but a must-have device for anyone working to exacting standards in a testing lab, museum, or manufacturing environment.

best,
Mark
http://www.aardenburg-imaging.com

[Mike Guilbault]

Thanks guys... that's a lot of good information.  I think I'll take a look to see if I can get the HygroSet here in Canada - or possibly the Caliber IV.  I found out today that the problem was my humidifier. Although the fan was churning, no moisture was coming out.  I changed the filter and cleaned it up a bit (it really wasn't that dirty though) and the humidity started to rise. It went from 16% to 37% before I left for the day and was steadily climbing. I expect, and hope, it'll be above 40% when I go back in the morning.  The two hygrometers I have were actually reading within a couple degrees of each other when I left. I suspect that at the lower humidity (-20%) that the one wasn't reading accurately which can be a problem for some hygrometers at low humidity levels.  I'd still like to get one that is more reliable so will definitely look into those suggestions.

[dwswager]

With forced air heat, especially a gas furnace, cold temps and the furnace running alot, 23-26% sounds about right.

Now that you know the humidity is low, what are you doing about it?    I just put a small baby cold humidifier in my office.  It would be hard pressed to get over 60% with the heat running.

[MHMG]

I expect, and hope, it'll be above 40% when I go back in the morning.

One needs to be aware of the danger of elevated indoor humidity levels in extremely cold northern winter climates like Ontario or for that matter many regions in the United States. Indeed, during the last few decades many museums around the world which attempted to maintain a "flatlined" 50%RH + or - 5% RH year round (widely advocated by "experts" with the not entirely accurate belief that it was essential to the well being of cultural artifacts within the building) found out the hard way that unwanted consequences could occur.  In some cases, entire plastered cathedral ceilings came tumbling down due to unseen condensation effects behind the walls. Major structural damage to window casings and interior framing components of the buildings occurred.  If you aren't in an isolated interior room in the building (i.e, no walls in the room serving as an outer wall to the building) you may not be able to sustain moderate humidity levels (35-50%RH) at normal "human comfort zone" temperatures inside the building without risking physical dry rot or worse to the structural framing components of the building. You will need to accept lower RH values like 25-30% at best and perhaps set thermostat to lower temperatures (45-60 degrees F).  Please be careful! This is a serious issue that should not be ignored for folks living in regions where very cold seasons occur.

During these very cold spells in my studio in western Massachusetts, I have to accept about 25% RH maximum. Higher than that and I begin to see condensation on the inside surface of my windows in my studio! What I can't see is the potentially extremely high moisture content building up within the wood framing timbers of the outer walls as the warm interior moisture migrates through the paint and plaster towards the colder gradient temperature zones within the walls. Ultimately, holding the desired higher humidity levels in a room may lead to dry rot or worse within the room's outer walls over a period of years due to the wall's temperature gradient from inside to outside surface. Hence, due to building's design and construction, I can only safely add a modest amount of humidity into my print studio room during the coldest periods of the winter months. Sometimes, on the coldest days, I simply don't try to hold humidity high enough to print. I don't print on those days.


cheers,
Mark
http://www.aardenburg-imaging.com

[datro]

I use the Lufft hygrometer/thermometer which is distributed by Abbeon in the U.S.  Amazon has it here.  I have it mounted on the wall behind my printer.  It is German-made and is certified.  If you want accuracy, you will be happy with this.

Dave

[Randy Carone]

I also use the Lufft Hygrometer/Thermometer (in my guitar room) with a Venta Airwasher humidifier.