New humidity gauge, how to calibrate it?

[secuono]

Ok, so I put it in a metal valentine candy container, all I had. I put in half a cup of salt, again, all I had. And I placed it and the salt in there about a day and a half ago, last night it read about 40%. Today, it was at 60% humidity. Checked an hour ago, still at 60, so does that mean it is 15% off than what it is supposed to say? Since someone told me it should be 75, so any more or less you need to add or subtract when I use it. Should I use more salt? It's one of those that looks like a clock, so it has an arm, can I move it now when it's at 60, up to 75 and then I don't have to do math later?
Please help, thanks!!

 

[A.T. Hagan]

Here's the best article I've found on calibration yet: http://ezinearticles.com/?Prevent-Mold!-Hygrometer-Calibration&id=602308

I haven't use all the methods it lists, just the table salt (sodium chloride) one and it works well.

 

[secuono]

So I forgot the water! Lol.
thanks

 

[A.T. Hagan]

Use a heavy Ziploc bag for this. That much concentrated brine will eat up your Valentine tin pretty quick and they often don't really seal air tight.

 

[secuono]

I cut off the thermometer, I have so many already, and put the humidity gauge in two little baggies with the damp salt.

 

[secuono]

It's now around 60...no idea what is going on or if I'm doing it right...

 

[debilorrah]

If you have the damp salt and the hygrometer sealed in the baggie, you have done it right. However, it takes 12 hours.

 

[secuono]

it's at 70% now....what the heck...
How much air should be in the bag?
The salt is wet enough it wiggles, then added a bit more til it was more stiff, but wet. Is that good..?

 

[debilorrah]

I believe the recipe is 1/2 cup of salt and 1/4 cup of water in a coffee mug, put that and the hygrometer in the baggie and seal it and leave it for 12 hours. At the end of 12 hours, that is your result.

Start over, leave it closed and don't mess with it this time!

 

[secuono]

I didn't mess with it. It's been in the baggie all day, got as much air out as I could though, guess that was bad..?