How long to salt test??

Troop_lee

SilverBack
Ok, I am salt testing my three hygrometers (again). They have been in for 9 hours now. I am just wondering how long I should do this for. I have read on here one user says 36 hrs, one said 24 is fine. Two web sites say 8 is long enough. I recorded there readings today and here go's

2hrs 4 hrs 8 hrs 9hrs
Digital #1 72% 75% 78% 78%
Digital #2 66% 70% 72% 73%
Analog 70% 71% 71% 72%

The digitals, are both "Cheap" ones from giant corporate devils ;)

Same brand, different cases. Both have been modified (by me) to allow for more airflow to the metering probe.

So how long should I continue this for?

Thanks
 
My experience was that 24hrs seemed to be the maximum time needed for the RH readings to stabilize. IMO, it depends on your mixture ratio (salt/water) and volume of space (size of bag) you are using plus the ambient air temp. Your mileage may vary.
 
My experience was that 24hrs seemed to be the maximum time needed for the RH readings to stabilize. IMO, it depends on your mixture ratio (salt/water) and volume of space (size of bag) you are using plus the ambient air temp. Your mileage may vary.

volume of salt, water, and airtight container determines how long the test should last. I use a 1 quart container with a Boveda, and I give it 3 days. Smaller the container, and faster that it will stabilize. be patient. when the humidity reading has not moved for a couple of days, then you are done.
 
Thanks, I'll give till till I get home tomorrow. But then I need to get them in to my new coolidor to make sure it is stabilizing.
 
Yeah I am just doing the salt test myself at the moment. Alot of websites out there say do it for 4, 8 or 12 hours.

At 4 hours my reading was at 74%, 8-12 hours it was at 75% and at 24 hours it was 78%. It has now been 33 hours and is at 76%.

Do I just keep waiting untill it doesnt change anymore?
 
It depends on a lot of things. First of all make sure the bag or container you are using is sealed well. If you are using a bag, double bag it. A plastic container works well.

The humidity inside the container at the start will influence how long it takes to stabilize.

I wait until the reading is stable for 24 hours. Usually 24-48 hours and then wait until the next day.
 
It has now been 42 hours and is sitting on 75%. Common Credo hygrometer - you can be perfect - just hold it for a few more hours!!!!!!
 
I use a mayo jar lid heaped full of salt and a gallon ziplock baggie and do about a half dozen hygros at a time.
For my own interest I've watched (albeit loosely) to see how long it takes for the bag to reach 75 and stabilize. It takes about 15 minutes.
I leave my hygros in for at least an hour, calibrate them through the bag (without opening the bag), then leave them in there at least three or four hours. Sometimes I forget them and leave them there for days. :)
 
I found the best way to do a salt test was to use my herfador 15 ct. That has a darn near air tight seal on it. I don't think ziplocks are as effective for the salt test. The herfador does great.
 
My hygrometer has been in there for over two days now and it is still changing. In the morning and day it seems to be 75% and in late afternoon to night it rises to 79%.

Whats going on???
 
My hygrometer has been in there for over two days now and it is still changing. In the morning and day it seems to be 75% and in late afternoon to night it rises to 79%.

Whats going on???

Is the temperature fluctuating noticeably from morning to afternoon? Since we are measuring RELATIVE humidity, and the holding capacity of air changes with temperature... this could explain the variation you are seeing...
 
Hmmm I think so. When the tempreture is about 15 degrees C (59 F) I get 75% and when the tempreture rises to 20 degrees celcious (68 F) the humidity is about 78-79%. So with this constant flucuation how do I know if my Credo hygrometer is accurate or not? It is a Credo hygrometer and they are ment to be extreamly accurate.
 
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