View Full Version : Caliber III, Hygroset III hygrometers and Boveda calibration bag quickly reviewed

Beau Hannam Ukuleles
11-04-2013, 06:05 AM
Thread title should read Caliber IV, NOT Caliber III ;(

In the pics are a Caliber III, the newer Caliber IV and a Hygroset III (with the red button) $19 each and a Boveda 75% calibration bag ($5)

The Caliber IV is the one stew mac sell for $29.40 but get it new on ebay for $18.95 with FREE shipping. The calibration bag cost $5 a lasts 3 months and is worth it.

All were bought from http://stores.ebay.com/HumidorPros

Both the Caliber IV and hygroset can be (re) calibrated by the user- The older Caliber III cant.

The procedure for calibration is to put your hygrometer(s) in the zip locked calibration bag for 24-36 hours until the bag reaches its (in this case) 75% humidity environment- note some bags had a different % level- it doesn't matter what number you buy though.

Both are suppose to be calibrated and working accurately out of the box. Neither read 75% after 36 hours in the calibration bag but that was no surprise.

Simply put, I found that the new Caliber IV is the best because (in order of seriousness):
1- It can be calibrated while still in the zip lock bag as it has push buttons and a simple interface (for lack of a better word),
2- it seems to react quicker to humidity change.
3- It has only 2 buttons, which do more then the hygrosets 3 buttons!
4- the instructions are better.
5- it comes with a 2 magnets to attach to where thou desires.
6- it is a better size- the Hygroset is a little to small.
7- "Caliber IV" sounds cooler then "Hygroset III"

The Hygroset III uses a small turn knob to calibrate. One click left or right Calibrates +1 or -1 % however it is done by feeling the clicks- there is no visual representation of a digital number going up or down. I found this a flawed idea.
Also, this knob cant be rotated in the calibration bag- by the time you get the thing out and turn it, it is already reading the outside environment and your chasing your RH tail. Of course, this isn't a problem if you can read off something another known working hygrometer but if you had only bought the hygrosett III, it would be a problem.

A side note- my Caliber III is about 2 years old and was only about 3% off 75% :)


11-04-2013, 06:53 AM
Beau, how will you humidify your shop in the Winter if you decide it is necessary?

Beau Hannam Ukuleles
11-04-2013, 07:01 AM
I have 2 x humidifiers- I got one last year then I found another HUGE one at a yard sale on the weekend!
I also got a de humidifier from goodwill for $10 a week ago, so that will come in handy for about 2 days a year in Colorado- actually, it does get high enough to use it.

i got a 24" twin drum sander on the weekend too for $350 :)

11-04-2013, 12:40 PM
Thanks. In the upper US we are starting to break all that stuff back out. I never could get my Hygroset dialed in and like the Calibers. Being able to calibrate one at that price is wonderful!

11-04-2013, 12:50 PM
Thank you for posting this. I need to order a hygrometer, but have been a bit overwhelmed by the options.

11-04-2013, 02:54 PM
not sure how that calibration works, but if you can 'manually' calibrate it to a known reference, a sling psychrometer (measures wet bulb, dry bulb temps, and reads the RH ) is very accurate, fast, and not too expensive. Can these units be set to a known humidity level? Or is there some voodoo with the bags?

Beau Hannam Ukuleles
11-04-2013, 03:44 PM
The $5 calibration zip lock bags come with a satchel which is the catalyst for administering the humidity environment according to the big number printed on it- I got the bag with a 75% satchel but there are 60% satchels, etcetcetce- it dosen't matter which you get. These are made for cigars BTW so apparently cigars are more delicate then ukes!

if you put 1/2 a cup of salt in a zip lock bag and leave it for a day, it creates an environment with a RH of 75%. The manufacturers say not to do this as they want to sell calibration bags and that it corrodes the electronics. Maybe. I haven't tried the salt test but im told it works.

11-04-2013, 03:53 PM
so theoretically, you could know the RH of your room, and set the unit to the known level? instead of using the bag?

if so. a sling psychrometer might be the 'bees knees'. It could be used to check accuracy as often as you are comfortable, as well as calibration when needed. It is used as a laboratory standard for checking RH. IIRC, they used to cost about $40 for a nice Taylor SP. At $5 / bag, it would pay for itself pretty quickly.

Beau Hannam Ukuleles
11-05-2013, 03:31 AM
You may go through a bit of salt though-

$5 a year aint much
it may be more accurate the the + or - 5% they cite in the link below. i should do a test for the sake of science and the betterment of UU knoweldge.


another link


I hadnt thought of just putting it is a really wet place (such as a bath room during a shower) and setting it to maximum- it would be interesting to see which is more accurate.