# Hygrometer calibration



## oldfogey8 (Jun 21, 2014)

so i have never tried calibrating my hygrometer. it is a caliber 3 and i was under the impression it would be pretty close to in range. so i bought 3 cheapo hygrometers and i figured i'd get an idea of how close they were to my 'good' caliber 3. they were off by 1-4%. compared them to my house hygrometer and they were all off from that. so i looked on the intraweb and found a couple of sites showing how to do it with a capful of salt and a little water in a ziplock bag. well they are all way off after 18 hours, like reading 65-68. i know they say to just use the offset but are these too far out? not sure they respond linearly. do these numbers sound way off? my cures have been less than optimal. i am thinking using the caliber has made it so i have kept the jars above the cure zone for too long. my long term storage i have boveda 62's in and one that i had in the closet for 4 or 5 months. the pack is still nice and soft. i have read that when they have been used up, they get hard. thanks in advance...


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## Hackerman (Jun 21, 2014)

I have about 10 hygrometers of all kinds from the Caliber to the cheapo analog ones. I calibrated using the salt water method and my Calibers were off as much as 4 or 5% before calibrating.

I'm not sure if the hygrometers are just like this or if it's the salt water method but I did mine 3 or 4 times and they came up a little different each time.

I think if they are within a couple percent that is close enough. Still, all my models are anything but 100% consistent.


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## oldfogey8 (Jun 21, 2014)

cool. thanks for the feedback, hack.


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## ArtVandolay (Jun 21, 2014)

Hackerman said:


> I have about 10 hygrometers of all kinds from the Caliber to the cheapo analog ones. I calibrated using the salt water method and my Calibers were off as much as 4 or 5% before calibrating.
> 
> I'm not sure if the hygrometers are just like this or if it's the salt water method but I did mine 3 or 4 times and they came up a little different each time.
> 
> I think if they are within a couple percent that is close enough. Still, all my models are anything but 100% consistent.



Once you know how far off they are you know how to adjust their readings. I stick a piece of tape on the back of each hygrometer: +2, - 3, etc.

nvthis did a great thread on curing that included how to calibrate hygromters. I'll see if I can find it.


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## ArtVandolay (Jun 21, 2014)

Here it is

http://www.marijuanapassion.com/forum/showthread.php?t=54451

Sorry that's an edited version of nv's post, don't bother. I don't know if the original has survived. The main trick is to test them all at the same time (in the same jar, etc.)


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## Hackerman (Jun 21, 2014)

I am going to do a thread on all the different models I have as soon as I get some time. I'll put them all into a large glass cake pan with a sealed lid. If I do it upside down I should be able to get pics of all the units under the same roof.

So far, I did just what Art said. (For the units that don't have calibration adjustments) I just put a piece of tape with + or - adjustments on it.

In the testing I have done so far, after calibration, they all seem to work about the same. Some can be calibrated and some can not but they all seem to hold a consistent reading. Even the little cheapo analog units.


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## oldfogey8 (Jun 22, 2014)

the 'curing by the numbers' thread is what i have been trying to emulate actually, art. i thought it sounded like an easy, fool proof method. if my hygrometers are actually off as much as the calibration using salt shows, then i have had the buds at above 70% since i jarred them up. no mold fortunately but the ash looks pretty black(probably because it is so frickin' wet!). i have a bunch of boveda 62 packs. to see if the hygrometers have a relatively linear response, i think i might stick the hygrometers in a bag with some of those packs for a half a day. oh and i have used a sharpie to mark the individual hygrometers with their current offset relative to the 75% calibration i have done... thanks for the input, art and hack. i appreciate it.


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## oldfogey8 (Jun 23, 2014)

so i stuck the all 4 hygrometers in a sealed baggie with 8 of the boveda 62's. now the calber 3 is reading 63 and the cheapo ones are 64,65 and 69. these values are pretty much what they were reading with the salt and water in a bottle cap method when they should have been reading 75. now i am just confused. seems like the boveda packs should keep the back at 62, right? if so, since 62 is closer to what i want my buds to be, it seems i should be using this offset instead.


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## ArtVandolay (Jun 23, 2014)

In the absence of the boveda pack, I average all the values and use that for the "real" rh (Ima statistics major). I put the boveda pack in when I'm happy with the rh and put them away  for months at a time. I wouldn't lose any sleep over all this.


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## oldfogey8 (Jun 23, 2014)

thanks artie-the-one-man-party. i am a weeeeeeeee bit ocd. i think i am probably over-thinking it but i have close to 8 oz's and i want 8 z's of nice smoke instead of 8 of so-so smoke. don't get me wrong. it is pretty kick *** at the moment (for me) but i want to get it as close to it's potential as i can.


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## ArtVandolay (Jun 23, 2014)

oldfogey8 said:


> thanks artie-the-one-man-party. i am a weeeeeeeee bit ocd. i think i am probably over-thinking it but i have close to 8 oz's and i want 8 z's of nice smoke instead of 8 of so-so smoke. don't get me wrong. it is pretty kick *** at the moment (for me) but i want to get it as close to it's potential as i can.



:rofl: You can always grow more :hubba: We haven't yet discussed your long term storage method and it's highly unlikely it's 100% airtight, anyway


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## oldfogey8 (Jun 23, 2014)

i have a vacuum sealer with the mason jar attachment. seems like it keeps things pretty air tight. using my caliber 3 now in successive jars of the first plant i harvested. one was at 60. the second at 58. letting the third jar reach equillibrium now. i put a boveda 62 pack in each of the other jars and i am planning on sealing them up tomorrow for a while. probably smoke the third jar (i split it up with my sons who smoke a ton more than i do) if is it in the zone. the second plant is still in the 65-ish range(4 jars).


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