Reliable Hygrometer Calibration for the Luthier

[Mike Thomas]

I don't know whether the potassium carbonate I bought from BioMed Cafe is different from the stuff they are selling now, it was quite a few years back. I suspect that the difference between food grade and lab. grade is not likely to be sufficient to create significant errors for our purposes. Food grade is defined as not having contaminants that are dangerous to health, but may have food safe contaminants e.g. fillers. Potassium carbonate is a cheap product and unlikely to warrant the use of fillers. I was, and still am, happy that it gave an accurate result. Bob Connor also bought some from the same source, but I don't know what his experience was.

[Luke72]

I wasn't able to find potassium carbonate on the biomed web site, only the BI-carbonate. I have seen carbonate on the electronic bay shop cheap enough....
https://www.ebay.com.au/itm/Potassium-C ... bHpHlBOM-g

[simonm]

A few years ago there were two threads on mimf about calibration. This is the second one started by, and illustrated by Mario Proulx http://www.mimf.com/phpbb/viewtopic.php ... 01&p=15571

It demonstrates a very simple dew point method to calculate the relative humidity. All you need is a container, water, ice and a good thermometer and a means to do the relevant calculation. A five minute job once you get yourself organized.