Official Luthiers Forum!

I just received my Abbeon hygrometer back from Abbeon where I had sent it to be calibrated.

Since my move I noticed that my two Caliber II hygrometers were no longer reading the same.

Anyway from the picture below you can see that none of the hygrometers agree with each other now...... I think that I will take the word of the Abbeon for now........

You mean--- ---analog is more accurate than digital?!? But, but, the numbers are displayed exactly, in glorious LCD!

Congrats on getting the real deal.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Hesh, what did they charge to calibrate it, how long had you had it, and how far was it off?

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http://www.chassonguitars.com

Kent my friend it was about $30ish if I recall. They have two levels of calibration available. The $35 special..... is calibrated against a known in house standard and guaranteed to be with in 2.5%. The $75 deal is calibrated to be NIST certified. I sent mine away Priority mail and it took them less then 2 weeks to have it back to me.

Howard I completely agree and still have and use a turntable to listen to records!

David Collins told me that he used to calibrate the Abbeons at Elderly and he would do this about 4 times a year. He said that they could be way off in only 3 months time....... So I decided that I should send mine off at least a couple times a year or buy David lunch more often....

That's a beautiful hygrometer. Gonna have to keep that brass all polished up!

Who wants stinkin' digital displays?

Hesh, would you say they are off "over" or "under" more often?

Aren't there ways to do this yourself, with water and a plastic bag or something. Had a link on this, but on the old computer.

I have 2 low end analog hyrgrometers, they were off when I first got the 'new' one (made in Germany, 1960's) but soon, the new one calibrated itself to the Woodcraft one about exact.

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

As I understand it, temp can do that! Sudden changes, like door being opened, temperature... drafts, can affect different hygrometers at different rates but settle down over time.

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

Sam right-you-are it is a very pretty instrument. I wanted to post a request for a chunk of nice rosewood to mount this on. That's the plan anyway.

Frie buddy I don't know if they are high or low, this is the first time I sent one to Abbeon and I have no way to tell. I have a Woodcraft one too, not shown in the picture, and it always says the same thing.......

There is a lot in the archives about how to test the actual RH with either a sling psycrometer or a wet bulb. My understanding is that not only do these things need frequent calibration but the range that you calibrate it for also makes a difference. For example you can calibrate them to be most accurate between 40 and 60% and they will do fine in that range but be inaccurate outside of that range.

If nothing else I will be able to tell to some level of accuracy what my RH is and even more importantly tell when it changes.

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Hesh,
The best way to test Humidity is with a sling psychrometer. "old school" for sure but a great way to ensure accuracy of your meters.
http://scientificsonline.com/product.asp?pn=3115800&sid=2008FS&eid=2008FS&mr:trackingCode=AD05F79B-1C80-DD11-AFF6-000423C27502&mr:referralID=NA&bhcd2=1221262857

Testing hygrometer accuracy.

You can test an hygrometer's accuracy in two common ways:

1. Wrap a damp cloth on the back of the hygrometer for 6 hours. The indicator should then read approx. 95%. If it reads lower or is off scale completely, merely adjust the indicator to read 95% using one of the methods described above.

2. Another way to check calibration uses table salt, a see-through container such as a Ziplock baggie, and a small shallow open container, like a bottle cap.
Place a teaspoon or so of salt in the shallow container and add a few drops of water - just enough to get it wet. Remember, you don't want a salt water solution, just damp salt. Place the shallow container in the baggie along with the hygrometer. (Make sure the salt does not get on the hygrometer, this may damage it).
Seal the baggie with some air trapped inside and let it sit for 6 to 8 hours. Check the hygrometer reading without opening up the baggie. It should read 75%. If not, remove the instrument from the baggie and adjust the reading to 75% with a small screwdriver.
To maintain accuracy of the instrument, it is advisable to recalibrate every six months.

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

Hey, rjeffery, that little psychrometer looks mighty handy and convenient. Do you have personal experience with that particular product? Would you recommend it (quality of construction, accuracy, etc)? Thanks.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

I have used this manufacturer and others to test the relative humidity (RH) in moist rooms that are used to cure concrete (for lab testing) and the RH during concrete placement for bridge decks. In the case of the moist rooms the RH reading of the psychrometer was used to "validate" the installed Hygrometer. It takes a minute or so to run the test and the unit is small enough to fit in an apron pocket. Because it must be swung, and there is the possibility of breaking the thermometers, I recommend the spirit filled rather then the Hg filled thermometers. The BACHARACH model is the one I am most familiar with.

You need to re-energize the hygroscopic thread that shrinks and swells and gives you your reading about every 6-9 months. Here's how you do it: fully soak a terry hand towel and wring it out. Place it around the hygrometer. In 1-2 hours, the gauge should read 95%. You can adjust the screw on the bottom to get to 95%. I then use a sling psychrometer to double check the hygrometer after I have re-energized the unit. In some cases, it takes a day to get both in synch. Once you have it calibrated, it should last for at least 6 months.

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Stay with the happy people.
--Reynolds Large

Thanks, rjeffery.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

It is interesting that you brought this up. I now have 3 hygrometers in my shop. One is a Taylor Digital, the other two are analog (manual ?) meters that use a hair to determine humidity.

I was paying more attention to the Taylor digital, assuming it was more accurate since it matched outdoor temp and humidity readings that were displayed by the National Weather Station which is less than 5 miles from my house. About a week ago, I went into the shop and the reading was at 20% on this display and I totally freaked out. I thought the air conditioner had depleted all of the humidity in the shop and began running 2 humidifiers to make up for the lack of moisture. After 3 days of this, it still read 20%.

Woodcraft has their clock/temperature/humidity meters on sale right now, so I bought one of them Sunday. It matches the other manual (?) meter on both temerature and moisture, so from now on I will pay attention to these instead. I am at a comfortable 55% humidity in the shop now. (and was before too if I had only paid attention) It is obvious that the digital Taylor hygrometer is malfunctioning. The clock still works on the Taylor, but is an hour off because I never did reset it for daylight savings time. The temperature still seems to be working ok on it too, but that doesnt do me a lot of good.

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Reguards,

Ken H

My own experience with digital hygrometers (and the cheap analog ones) has led me to the conclusion that they are virtually useless. Well, except for the income they provide to their manufacturers and sellers. The way to go is with a high quality analog hygrometer, calibrated (and checked on any time I am in doubt) with a psychrometer. Along with those it's cool to have a couple shop-made wooden hygrometers like I described in this thread - http://luthiersforum.com/forum/viewtopi ... 01&t=18756

If we want to avoid all the and and and , we gotta cough up the dough for the right tools. Then we can go !

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

The sling psychrometer from Edmunds linked above is the Taylor I believe. I have been using one of these for several years and highly recommend it.

There has been so much discussion about this issue for years that i am surprised that any regular reader of this forum still does not consider hygrometer calibration as essential. Here is my story: a few years ago I bought 2 digital hygrometers from Stew-Mac and was impressed how they agreed to the tenth of a percent. They also indicated that the humidity was about 15 points lower than my uncalibrated analog. So, impressed with such digital accuracy, I ignored the old analog and humidified the shop enough to get the readings up to the normal range. After a couple of weeks of this, I became suspicious of the Stew-Mac instruments and bought the Taylor sling psychrometer. It turned out they were nearly 20 points off when they read in the mid-40s, but man, they sure agreed with each other nicely! From what has been said on this forum the digital hygrometers that they sell now are better, but I personally will never use a digital again.

I complained to Stew-Mac and they replied that hygrometers were only to give a relative indicator of rise and fall of humidity, No offer of my money back, even though I told them of a top that pulled itself apart after the levels were brought back to normal. I used one of them for target practice and the other for temperature alone.

Several points:
- If you do not have a calibration method in place, regard your hygrometer(s) as useless, NO MATTER HOW MANY YOU HAVE THAT AGREE WITH EACH OTHER.
- The outside RH has no useful relationship to the inside RH. Forget the weather reports! I have measured the RH outside my shop as swinging from 25 to 60 percent in 24 hours, while the inside stayed at 43 to 44 with no climate controls.
- If your hygrometer does not have a calibration screw, then toss it - you will be happier in the long run .
- Used Abbeons (like Hesh's) are frequently available on ebay for very reasonable prices. There is very little that can go wrong with these things. I have 2 that each cost less than $50 each.
- An alternative that I have been testing is the $26 Conant: http://www.amazon.com/Conant-Custom-Bra ... 601&sr=8-5 I have found this one to stay within 2 points of accuracy in the normal shop range. It does vary more than the Abbeons as the RH gets outside of the normal range. Its big advantage is that it is easy to read and easy to calibrate.

Brook

I've had more problems with mechanical than digital.

One question I've always had about sling psychrometers...why doesn't the centrifugal force of slinging them effect the mercury reading?

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http://www.chassonguitars.com

I have wondered that also and have not found a real explanation. My assumption is that since both thermometers are being twirled, the centrifugal force affects both the same and thus is not a factor, at least for non-laboratory uses. The dry bulb temperature does change during the twirling. I am curious to know if it changes in the stationary type psychrometers also.

Brook