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Thread: Measuring Humidity... What's a Guy To Do?

  1. #1

    Default Measuring Humidity... What's a Guy To Do?

    I have 9 hygrometers in my music storage room and they all measure differently. Let's skip the one that says 39% because that one is obviously wrong. Ironically, the highest reading of 57% is on a hygrometer (shown with a red dot) that I recently purchased from a violin shop that calibrates each unit before it is shipped.

    I don't know which one to trust.

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    Registered User sunburst's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    I have three in my shop and all read differently. I just sort of take an average.
    Many of them can be calibrated. There are instructions online.

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    Registered User John Flynn's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    I use an Inkbird humidity controller. It turns my humidifier on at 46% and off at 50%. It will give an alarm at 45%. From what I can tell, it seems pretty accurate. I tried calibrating it with the salt test, but it seemed good out of the box. I figure that even if is not perfectly calibrated, it keeps the instruments consistently humidified, no big swings up or down.

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    Default Re: Measuring Humidity... What's a Guy To Do?

    I use a few of the Oasis Caliber IV hygrometer which looks almost identical to yours with the red dot. I've found them to be accurate and easy to calibrate using the salt method. Once you calibrate that one with the salt test, you will know that it's accurate and you can use it to evaluate the others.

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    coprolite mandroid's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    Relative humidity , even the measurement may be relative ?
    compare it with what the National Weather service gives you on that day where you live?
    of course that is outside RH. but set them all out and see which one agrees most closely?

    water on 3 sides of me, south , west . north here (& not snowing so abundant rain = 4 sides)
    so I don't worry about too dry..
    writing about music
    is like dancing,
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  9. #6

    Default Re: Measuring Humidity... What's a Guy To Do?

    I tripped over these years ago, they come calibrated to within 1-2% from the factory, and the calibration kit can get it to +/- 1%.

    The kit is just a bag with some special salts, you leave them in for an hour, so it takes a while to calibrate properly, I calibrated one in the bag, then matched the others to the calibrated one. You have to be careful not to heat them up with your touch (and let them cool down), as that throws off the calibration.

    I have three, they all read the same, all the time. And the calibration survives a battery replacement.

    Before I discovered those I bought several 'consumer' humidity meters, and they disagreed with each other enough to be useless (more than 10% apart).

    https://www.amazon.com/Quality-Impor.../dp/B0055QM9V2

    There are other accurate ones to be had for sure, but the field is cluttered with junk too.
    Davey Stuart tenor guitar (based on his 18" mandola design).
    Eastman MD-604SB with Grover 309 tuners.
    Eastwood 4 string electric mandostang, 2x Airline e-mandola (4-string) one strung as an e-OM.
    DSP's: Helix HX Stomp, various Zooms.
    Amps: THR-10, Sony XB-20.

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    Default Re: Measuring Humidity... What's a Guy To Do?

    Quote Originally Posted by John Flynn View Post
    I use an Inkbird humidity controller. It turns my humidifier on at 46% and off at 50%. It will give an alarm at 45%. From what I can tell, it seems pretty accurate. I tried calibrating it with the salt test, but it seemed good out of the box. I figure that even if is not perfectly calibrated, it keeps the instruments consistently humidified, no big swings up or down.

    Click image for larger version. 

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    I have been using the Inkbird that I calibrated against my Caliber IV. I use the Caliber next to the instruments and the Inkbird across the room controlling the humidifier. In the same room there is a typically 3-5% range of difference between them. Not a big deal at all. The big thing is to prevent any large swings. That said, what I would do is take out the four outside measurements, then average the inner five. Calibrate them all to that number and give them a few hours. Then give away anything that is a drastic outlier to the new average. With nine of them you should find the trash pretty fast.

    Like "they" say...We ain't building watches.

  11. #8
    Adrian Minarovic
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    Default Re: Measuring Humidity... What's a Guy To Do?

    I've got the Caliber IV as well and also lab hair hygrometer and they agree (and did pass the salt tests). The Caliber is way too much sensitive in some spaces and it willl even sense your breath within few feet away. Tha hair hygrometer does change slowerso it better reflects humidity in the whole room.
    Do the test with ordinary table salt for 75% spot and you can get magnesium chloride hexahydrate (if I recall correctly) to check the 33% spot. You can also close them in a sealed clear plastic container over a sopping wet sponge and they should read close to 100% after some time.
    Adrian

  12. #9
    Likes quaint instruments poul hansen's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    Calibrate with potassium carbonate just made wet with water, without being totally dissolved (a saturated solution)will produce a humidity of 43% in a sealed container or closed plasticbag, in some hours. Just the range where you want to measure.

    For hygrometers , that can't be adjusted, discard if more than 10% rh wrong, if less, just mark the meter with the correction.

    Potassium carbonate is sold as an ingredient for baking cookies.
    Kentucky KM-805..........2 Hora M1086 Portuguese II(1 in car)
    Hora M1088 Mandola.....
    Richmond RMA-110..... .Noname Bearclaw
    Pochette Franz Janisch...5 Pocket............Alfredo Privitera pocket
    Puglisi Pocket 1908........Puglisi 1912.......Puglisi 1917
    3 Mandolinetto ..............C.Garozzo
    1 Mandriola...................Cannelo G. Mandriola...Böhm Waldzither 1921
    Johs Møller 1945............Luigi Embergher Studio 1933
    Marma Seashell back......Luigi Embergher 5bis 1909

  13. #10

    Default Re: Measuring Humidity... What's a Guy To Do?

    I ordered one of those inkbirds, I like the idea, my place drops below 40% RH in the winter, if it can keep it somewhere near 48-50 that would be great.
    Davey Stuart tenor guitar (based on his 18" mandola design).
    Eastman MD-604SB with Grover 309 tuners.
    Eastwood 4 string electric mandostang, 2x Airline e-mandola (4-string) one strung as an e-OM.
    DSP's: Helix HX Stomp, various Zooms.
    Amps: THR-10, Sony XB-20.

  14. #11
    Likes quaint instruments poul hansen's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    I have an Inkbird type as well but my humidifier will not start at power on, I need to push a button for that :-(
    Kentucky KM-805..........2 Hora M1086 Portuguese II(1 in car)
    Hora M1088 Mandola.....
    Richmond RMA-110..... .Noname Bearclaw
    Pochette Franz Janisch...5 Pocket............Alfredo Privitera pocket
    Puglisi Pocket 1908........Puglisi 1912.......Puglisi 1917
    3 Mandolinetto ..............C.Garozzo
    1 Mandriola...................Cannelo G. Mandriola...Böhm Waldzither 1921
    Johs Møller 1945............Luigi Embergher Studio 1933
    Marma Seashell back......Luigi Embergher 5bis 1909

  15. #12

    Default Re: Measuring Humidity... What's a Guy To Do?

    Is my nest thermostat good enough? It always reads around 40-50 no matter the time of year (Utah).

  16. #13
    Likes quaint instruments poul hansen's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    Quote Originally Posted by mandokismet View Post
    Is my nest thermostat good enough? It always reads around 40-50 no matter the time of year (Utah).
    Put it in your bathroom next time you take a shower and see if it moves or breathe into it.

    Or do a calibration check as described above
    Kentucky KM-805..........2 Hora M1086 Portuguese II(1 in car)
    Hora M1088 Mandola.....
    Richmond RMA-110..... .Noname Bearclaw
    Pochette Franz Janisch...5 Pocket............Alfredo Privitera pocket
    Puglisi Pocket 1908........Puglisi 1912.......Puglisi 1917
    3 Mandolinetto ..............C.Garozzo
    1 Mandriola...................Cannelo G. Mandriola...Böhm Waldzither 1921
    Johs Møller 1945............Luigi Embergher Studio 1933
    Marma Seashell back......Luigi Embergher 5bis 1909

  17. #14

    Default Re: Measuring Humidity... What's a Guy To Do?

    You can't vote on the truth, so multiples don't really prove anything. The inexpensive ones that claim 1% accuracy are making claims are simply impossible. I use professional grade versions at work, costing many hundreds of dollars and requiring factory calibration periodically. The spec on most of those is 2% accuracy from 10-90%. And really you don't have to have 1% or even 2% accuracy. More than anything else we use hygrometers as a "switch" to tell us when to start humidifying and when to stop.

    The most reliable "self check" without doing a salt test of some sort is a sling psychrometer. It consists of two thermometers and cotton sock on one of them. The different it wet and dry bulb temperatures tells you the relative humidity. They never need calibrating, you don't have to buy more test supplies, and they will last many lifetimes if you don't break them. You can get one for about $100 or less if you shop around. They are easy to use, but one trick is putting it at the end of a suction hose on a vacuum cleaner. You'll get the room wet bulb temperature in about 10 seconds. No guesswork.

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    Registered User sunburst's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    Wet-dry bulb hygrometers are the gold standard, but Adrian's aforementioned hair hygrometer is extremely accurate (and used to calibrate other hygrometers, so I'm told) and it's easy and inexpensive to make one.
    https://www.wikihow.com/Make-a-Hygrometer

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    Default Re: Measuring Humidity... What's a Guy To Do?

    Quote Originally Posted by poul hansen View Post
    I have an Inkbird type as well but my humidifier will not start at power on, I need to push a button for that :-(
    Yep, found that out the hard way. I had an older version humidifier that had a manual rotary switch that worked fine (you could just leave it on whatever fan speed setting you wanted) until one of the motors seized. I got a newer (used) one that has has the push button controls and needed to be pushed each time so the Inkbird would not work. I disconnected the whole humidifier board and direct wired the motors to an off/on switch and plugged that into the Inkbird. There are four wires on each motor but only two would make the motors spin when checked. The problem now is that the humidifier only works at top speed.....and sounds like a jet taking off whenever it is working. I have been watching the local craigslist and FB want ads for another older version with the rotary switch. The humidifier I have rewired is an Essick AirCare HD3120DCN.

    Again....all that is needed with the hygrometers is consistency. Not minute accuracy.

  20. #17

    Default Re: Measuring Humidity... What's a Guy To Do?

    Quote Originally Posted by sunburst View Post
    Wet-dry bulb hygrometers are the gold standard, but Adrian's aforementioned hair hygrometer is extremely accurate (and used to calibrate other hygrometers, so I'm told) and it's easy and inexpensive to make one.
    https://www.wikihow.com/Make-a-Hygrometer
    Mario Proulx used to make "indicators" from a piece of hardwood and spruce. If I recall correctly the hardwood was something about the size of a long paint stirrer, maple, cherry, something like that. Maybe a bit thinner than a paint stick, but about that wide with the grain running lengthwise. Spruce cuttoffs from tops were glued to one side when the shop humidity was known to be about 45%. (Of course you need a good way to measure that first.) Because the spruce changes more than hardwood dimensionally, and much more due to the crossgrain construction, the whole thing would bend one way if humidity fell and the other if it rose. If the stick was straight, then it was close to 45% in the room. It was a fun project, easy for most amateurs to do, and served as a quick visual even if it didn't really tell you the actual humidity.

  21. #18
    Registered User Sue Rieter's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    Quote Originally Posted by Buck View Post
    Mario Proulx used to make "indicators" from a piece of hardwood and spruce. If I recall correctly the hardwood was something about the size of a long paint stirrer, maple, cherry, something like that. Maybe a bit thinner than a paint stick, but about that wide with the grain running lengthwise. Spruce cuttoffs from tops were glued to one side when the shop humidity was known to be about 45%. (Of course you need a good way to measure that first.) Because the spruce changes more than hardwood dimensionally, and much more due to the crossgrain construction, the whole thing would bend one way if humidity fell and the other if it rose. If the stick was straight, then it was close to 45% in the room. It was a fun project, easy for most amateurs to do, and served as a quick visual even if it didn't really tell you the actual humidity.
    AKA "Yankee Weather Stick"

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    Registered User Mandobart's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    Oh jeez this is beginning to look like a well-known guitar forum where there are 2 - 3 humidity posts per day......

    A hygrometer is like a watch - when you have more than one you never really know the true value of the parameter you're monitoring.

    You CAN'T CALIBRATE consumer grade hygrometers. All the salt checks etc. are nothing more than a single point calibration check. That way you know that at one point it reads accurately (like a broken watch).

    A true calibration consists of setting the zero, span, and linearity as well as response at 5 or more cardinal points using test equipment traceable to NIST. I'm confident none of us are doing that.

    One thing I do is find out what my local weather station reports for relative humidty, then place my hygrometers outside and see what they stabilize at. Another rough ball park cal check at least as valid as a salt check.

    After owning, playing, storing and transporting stringed instruments from high altitude in NM to San Diego to Chicago to Orlando to Idaho, back to San Diego, coastal Washington to inland WA desert, I've learned not to get too puckered up about relative humidity ranging from 25 - 85%. Just avoid RAPID changes in temperature and humidity.

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    Default Re: Measuring Humidity... What's a Guy To Do?

    Quote Originally Posted by Mandobart View Post
    After owning, playing, storing and transporting stringed instruments from high altitude in NM to San Diego to Chicago to Orlando to Idaho, back to San Diego, coastal Washington to inland WA desert, I've learned not to get too puckered up about relative humidity ranging from 25 - 85%. Just avoid RAPID changes in temperature and humidity.
    What do you do if you're flying from the desert west to the humid southeast in summer? I'd like to take my nicer mandolin but not if it creates a problem.

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    Registered User Mandobart's Avatar
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    Default Re: Measuring Humidity... What's a Guy To Do?

    Quote Originally Posted by mandokismet View Post
    What do you do if you're flying from the desert west to the humid southeast in summer? I'd like to take my nicer mandolin but not if it creates a problem.
    Going from low humidity to high is not likely to cause damage. A neat thing about mandolins is they can be carried on the plane. If you check it as baggage it will spend several hours in the VERY LOW humidity in the baggage compartment.

    Treat it like you would a winter shipment - leave it in the case to slow down the transition.

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