Official Luthiers Forum!

Do you need a description of how to do the test?

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

What I read in some random site last night:

1) Put a small amount of the potassium carbonate in a small container. The site showed a lid to a 20 oz bottle half way full.

2) Put a small amount of water in the cap. Just enough to wet it.

3) Put the cap and the hygrometer in a gallon ziplock overnight.

If the hygrometer shows 45% humidity then it is accurate. If not, calibrate accordingly.

Is that how you test?


Sent from my iPhone using Tapatalk

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

Basically, yes. From what I read from a few different sources though, the RH for equilibration with potassium carbonate is at 43%.

I use a transparent tupperware type container (about 5" w x 9" l x 2" h) with a lid with a gasket and put the salt in a small ceramic dish (appropriated from the kitchen). You also need to use distilled water since salts in tap water could throw off the measurement. I let it sit closed for 24 hours. The amount of potassium carbonate you describe sounds similar to what I use in my tupperware container.

The way I do it is based on this post on the Australian/New Zealand Luthiers Forum (first post): http://www.anzlf.com/viewtopic.php?t=6123

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Perfect. Thanks!


Sent from my iPhone using Tapatalk

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

Mechanical hygrometers can easily be knocked out of calibration — can’t imagine Amazon shipping being delicate. Calibrate ALL hygrometers with K2CO3 on arrival and repeat annually. Photo shows a couple of my digital humidor hygrometers and the sensor for my wood-room humidity control system in a sealed plastic box with a dish of K2CO3, dampened with distilled water. They stay there overnight for adjustment the next day. (Humidity controller manages a humidifier and a dehumidifier on separate channels).


Sent from my iPad using Tapatalk

Testing is underway with the replacement from Amazon. Interestingly the RH spiked right away. I’m guessing it takes a while to stabilize and will come back down to the expected 43%?




Sent from my iPhone using Tapatalk

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

That replacement is looking much better right off the bat. Yes, it takes a while to equilibrate in there. Overnight at least depending on the starting RH value.

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Here it is after about 19 hours. The salt was rock hard when I opened the lid. Is that expected or did I not add enough distilled water to the mix?



Brad


Sent from my iPhone using Tapatalk

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

Probably not enough water. The potassium carbonate should still look wet and not be a hard rock.

I looked it up and found that a "saturated solution" of potassium carbonate can be made with a ratio of 1 ml of water per 2.2 grams of potassium carbonate. That's what you want to aim for. I'm guessing there's leeway around that ratio since none of the methods I've read call for exact measurements. You just don't want to add so much water that there is free standing water in the salts.

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Thanks, Jay. I’ll give it a try again tonight.

Brad


Sent from my iPhone using Tapatalk

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

43, 43, 44, and 44.... Looks like the new digitals are dead on and the old digital and new mechanical are +1.

I think we are good to go! Appreciate the help, Jay!


Sent from my iPhone using Tapatalk

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars