Official Luthiers Forum!

For a while now I have been looking for hygrometer solutions for you guys...

It seems that every time I weigh in on just how lousy the hygrometer choices out there especially with the digitals are I always am left disappointed because I didn't have a great suggestion to offer...

As always I still would highly recommend a couple of lab thermometers and learning to do wet-bulb tests as a way to calibrate and/or know the error rate of your hygrometer. The same holds true for the following recommendation.

What I wanted was a solution for the hobby builder that would be accurate, inexpensive, and not require a degree in physics to use...

I think that I found it:

I purchased three of these to test and ran tests for about three weeks as the seasons changed here in Michigan and I had to get out the four humidifiers that I use.... All three of these BestAir hygrometers read the same in ranges from 35% to just short of 60%. All three changed when changes happened and all three landed on the same percentage when ever something changed and I checked them out.

My big-arse Abbeon was also checked a few weeks ago with a Psycho-dyne and was only 1% off so I did not calibrate it. I also used the Psycho-dyne (glorified wet-bulb test...) to write where 48% was on this Best Air hygrometer pictured below.

As you can see in one of the pics the Abbeon and the Best Air read very close to the same percentage. And that boys and girls is the goal.

As such I would recommend these and again also suggest that you obtain a method to do wet-bulb testing so that you eliminate any possibility that the Best Air units that you purchase are not as accurate as the three that I purchased.

Two of the old farts that I jam with just left and so too did two of the Best Air units that I used for my testing. Both of these guys have Heshtone Guitars and it's a constant struggle to get them to understand the ravages of homes drying out on wooden musical instruments. So the two Caliber III digitals that they received with my guitars some years back and currently read all over the place.. have now been replaced with these Best Air units.

Best of all for these Best Air units..............................$8!!!!

http://www.amazon.com/BestAir-HG050-Hygrometer/dp/B007L8VEFY

Thanks!

Mmm, may need to come up with a graduated sticker to fill in the missing part of the scale.

Thanks for the tip Hesh.

Over the last week I have been testing an app that was recommended in your other post called Weather Station Pro for Android. I have all of my hygrometers sitting in my office and thought it would be a good time to check the calibration on them. I am using my Taylor sling psychrometer and have been testing a couple times a day. My 2 digitals are 5% and 9% low and have a fair amount of variation up or down, but my 2 German analog hygrometers are pretty much dead on. One is my Abbeon 167b (like yours without the temp) that I have had for years and the other is a Haar that I got for $5 a couple of years ago in a garage sale. Both of those are pretty much dead on. But surprising thing is that WS pro is pretty accurate and is consistently low by about 2% . I bought the Pro version after trying the free one only because it will track 14 days and you can print the graphs out.

But if anyone has an android phone check out the Weather Station app. It is free and seems to be pretty accurate within a couple of %. If you have the Galaxy 4s like I do it has temp, humidity and barometric pressure sensors built into the phone.


That Best air unit looks like a pretty good deal if it is accurate. I may have spring for one or 2 to hang in my shop. A lot cheaper to replace than my good ones...

Thank,
Bob

Hesh, thanks, got one on it's way now.
Economical to ship to UK/EU as well, which is great.
Will give me 3 hygrometers to check against my potassium carbonate.

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

@ Barry - Yep very true and you can see where I got out my Sharpie and wrote 48% on the face of the hygrometer. If I was justing one of these as my only "at a glance" hygrometer I would likely also annotate the entire 42% - 48% range on the face of the dial too. I should have mentioned that my take on any off the shelf hygrometer is to be ready to totally disregard it's current calibration and instead determine what it should read and mark it as such. That's where the wet-bulb comes into play.

@Bob - Thanks for that Bob and isn't it interesting that what seems to be more accurate for you (and me) are the traditional mechanical hygrometers instead of the plastic fantastic digitals.

I would highly recommend that others do what Bob has done, me too and that is gather up all the hygrometers that you can muster, beg, borrow, steal, or purchase and run some tests against a wet-bulb. It's very eye opening!

@Colin - good going and I hope that it serves you well! Interestingly I have a photo in my pics folder here of the instructions that came with the Caliber III's digitals. It specifically says that if we subject a unit to the salt test.... the warranty is null and void. You know kind of like if Louisville Slugger sold an expensive bat with a disclaimer that if you actually use the thing in a game and make contact with an actual baseball the warranty is null and void.... What's up with that....

Anyway the entire purpose for the post is that upon review of how our RH threads go it seems to me that some of us, especially me... are making this too complicated to follow and the recommendations are too expensive for some to follow. I'm just looking for a decent solution at a fair price that folks might embrace and hopefully produce instruments that last better.

I won't tell if you don't Hesh!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Good tip. I'll add a couple of these to my ever-growing hygrometer collection.

To me, the most critical element to the issue is the sling psychrometer.

FWIW, my Caliber IV has been performing well, although I've not had it all that long. Time will tell.

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George :-)

That's right and even though slinging is not all that convenient it does give us a "standard" to calibrate accordingly.

I used to recommend the Caliber hygrometers and have had them for years now. In the beginning they were pretty accurate and one time when I purchased three at once all read the same as the others. That was promising.

But what I found out over time was that the Caliber's can be pretty accurate in a small, defined range that in my experience just happened to be the range that we are most concerned with, 40 - 50%. I also found though that 55% on a Caliber might actually be 68% which was not a good thing.

Mine started to drift too and became more inaccurate when they were two years old. New batteries did not help.

A couple weeks ago David Collins took one apart and we learned that they rely on an electro chemical reaction as a sensor. You could see deterioration in the chemical.... "blob" and this likely is the cause of why they drift in time.

I still use my Caliber III's but with a piece of tape on them indicating the error. The one on my home thermostat has a piece of tape that says "reads 8% low..."

Let's remember too that hygrometers are typically not designed or manufactured for folks who require the accuracy that Luthiers do. Nonetheless once one understands and has wet-bulb testing stuff we can still use the commercial digitals with some tape and the ability to do simple math in one's head as a guide.

Interesting. Perhaps this explains why Caliber warns against testing their units using the "salt method."

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George :-)

Cool, thanks for experimenting and letting us know. I've been using the same hydrometer for 20 years and it was probably 20 years old when I started using it. I have no idea what kind it is and it was part of a set of hydrometer, thermometer, and barometer. The ladder two have since broken but the hydrometer always measures close enough. But these are so cheap I might get one for the second floor of the new shop.

Science Class!
Potassium Carbonate powder (~$12/lb at Amazon) + enough water to allow liquid and solid to exist in a slurry + a watertight container that fits your hygrometer or Hygrometer sensor + something to elevate your meter/sensor above the slush
This will create an RH in the container of 43.16% at 25C. You may also want to do the same with table salt for an RH of 73.5% at 25C. You may also want to do the same thing with Potassium Acetate ($13 at Amazon) for an RH of 22.5.

Temperature is critical in this exercise. RH is relative to the temperature. As temp drops and the amount of water vapor (absolute humidity) stays the same, the RH goes up. The RH drops in the same situation as the temperature goes up. Think table sugar in iced tea. Cold tea is almost impossible to get sugar into solution...Hot tea no problem. Don't make a knee jerk reaction to a high or low RH in a cold or hot shop. Wait for the temperature to stabilize.

Mark
(A slide rule guy in a Matlab world.)

I thought I would post some screenshots of the Android App Weather Station Pro that I have been testing for the last week.

It can be calibrated but I have not done that yet since I didn't know how good or useful it would be. For the most part it seems like a pretty good app and it seems to track the humidity and temp pretty well. I have tried to keep it in one location since when I first installed it the humidity readings were all over the place but I was taking my phone with me when I went downstairs or outside. Without being calibrated the humidity reads within a % or so from my Abbeon and my Haar but the temp reads about 10 degrees higher which is from the heat of the phone. I will probably calibrate it at some point to see if it corrects that but the humidity is what I was really looking to check.

All and all it is a pretty slick little app it has a widget as well as a monitor up in the left corner in the notification screen. The Pro version will track 14 days and you can save the raw data to a txt file. It has some neat other features such as moon phases and sunrise and sunset times. On the Galaxy 4s it will also track GPS altitude, Illuminance, Magnetic Filed. Not a bad little app and it seems to work great. The only real drawback is if you hold your phone for any length of time it reads the heat and humidity from your hand.

Here are a couple of screenshots of it.

Cheers,
Bob

The app is great, but leaving the phone in the wood stash / work area isn't all that practical.
Any chance there is a stand alone unit that works with the app?

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Wake up and smell the rosewood!

Yea... buy another phone...

Actually I don't see it as a replacement for a stationary hygrometer but seeing it is fairly accurate it is great for spot checking areas and as a reference against your other ones.

If someone gets anything out of these posts about humidity they should at least get the idea that you should never rely just on one or two hygrometers. The more references you have the more you will see which ones are accurate and which are not and be able to tell when one of them needs to be re-calibrated or replaced.

I actually have 8 of them. 4 upstairs 2 downstairs and one on my weather machine up on the roof. I keep 2 here in my office upstairs but that is where I keep all of my guitars. Plus I now have the one on my phone...

That may be a bit obsessive but I am confident that I know what the actual humidity is in my house and shop.

Bob

Funny, you could possibly do just that.
Finding out what OS and phones the app is compatible with may lead you in the direction of a cheap /used android phone to use solely for that purpose.

I have suspicion that it would however require a newer phone; doesn't hurt to investigate though.

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Wake up and smell the rosewood!

Thanks for posting this Hesh! Now I need you to find a way to make my humidifier/dehumidifier work with an accurate hygrometer so I can have a shop utopia environment....

_________________
ELEVATE || Next Level Lutherie
http://elevatelutherie.com
&
http://ensorguitars.com

The one thing I've taken away from the many discussions related to this topic is that I can have all the hygrometers in the world and still not know what the RH really is in my space. I can kind of, sort of, maybe, feel somewhat confident that I have a general idea that's probably fairly close, give or take a little bit here and there, but...

Buy or make a sling psychrometer, whirl it around for a couple of minutes and all the guesswork has been taken out of the equation. That was the real lesson, at least for me.

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George :-)

You only really need the one, for your workshop. The rest might be seen as OCD. . . and the vast majority of Guitar makers suffer OCD. Providing you can test that one Hygrometer, the one should be enough. Even though I have a sling Psychrometer my test relies on the Pot.Carbonate salt. I don't really care if my hygrometer is innaccurate at 55% or 35%. I just need to know if it's reasonably accurate in the 40 to 50% range and my (cheap) digital unit is out by 3%. It's been the same for the last 8 years, so I guess it's serving me extremely well.

Actually that is correct. I have a sling psychrometer that I use but it isn't very convenient to use to check the humidity every time you want to know. I use mine maybe once or twice a year but I do rely on my others most of the time. I can tell when one is off by referencing the others. So that was my point about having more than one.



I suppose that is true if you also store your guitars in your shop. I currently have 10 guitars and usually keep the ones I currently play upstairs in my office and the others in my music room which is on the other side of the house from my shop. So I guess you could call me OCD for having so many hygrometers.

Bob

I bought a couple of those and they are running high out of the box.
Could someone recommend a low cost sling please? Im tired of guessing if standard meters are correct.

Hi ya Wednesday - I'm wondering how you can know that the hygrometers are running high if you don't yet have a sling psychrometer or wet-bulb testing stuff?

To be more clear here I'm not saying that these hygrometers are uber accurate. Instead what I am saying is that they are "consistent in their inaccuracy" and as such with a Sharpie and wet-bulb testing stuff one can annotate on the face of the hygrometer the inconsistencies resulting in a budget solution that will be pretty close to accurate. Certainly better than nothing or an inaccurate digital or other mechanical unit.

Bob R. interesting app. I'm wondering if Android phones have humidity sensors that are being harnessed by the app or if the app uses the Internet connection to obtain Noah or other publicly available weather information and then display it?

UPDATE: Yesterday I put over 8 gallons into the air in my home via three humidifiers.... Feel like a water boy here.....

Hesh,

The Galaxy S4 has the sensors built in to it. Seven of them... it has Barrometric Pressure, Temperature, Humidity, Geomagnetic, RGB/Light, Infrared, Gyroscope and Accelerometer. Depending on the phone you have and how new it is some of these features are not all available.

But yea, the app is reading the phones sensors real time and not downloading them.

Bob

Sheesh Bob these smart phones are getting more and more amazing every day! Very cool!

Hesh,

I have to admit that $8 is a very reasonable cost for discovering RH. But there's an even less expensive way shown here by Robbie O'Brien:

https://www.youtube.com/watch?v=XhlyzoeA_7E

Steve