Replies

1. 
   RalphBarker | Jan 01, 2010 04:43pm | #1

   Don, I believe that "accuracy" is usually expressed as a percentage of the indicated reading. So, if it reads 25%, ±5% would mean that reality is somewhere between 26.3% and 23.7%.

   I haven't surveyed what relative humidity gauges are available, but I'd assume "home" (relatively inexpensive) gauges wouldn't be particularly accurate, relatively speaking, but rather intended to indicate broad ranges of "comfort".

   What is your objective in having gauges in both environments? Predict changes in MC once pieces move from one environment to the other?

   Edit: You might need to talk directly to the manufacturer to get two gauges that read the same.

2. 
   Quickstep | Jan 02, 2010 09:23am | #2

   Relative humidity is very important to luthiers, so I suspect that gauges available from luthier supplies might be more accurate. Here are a couple of links:

   http://www.stewmac.com/shop/Tools/Measuring_tools/Digital_Humidity_Gauge.html?tab=Pictures#details

   http://www.lmii.com/CartTwo/thirdproducts.asp?NameProdHeader=Hygrometer

   http://www.bridgebonebeads.com/index_files/Taylor5565Hygrometer.htm

3. 
   northhouguy | Jan 02, 2010 10:26am | #3

   Try this:

   http://www.amazon.com/Caliber-III-Digital-Thermometer-Hygrometer/dp/B0007W1EA6/ref=sr_1_1?ie=UTF8&s=home-garden&qid=1262445776&sr=8-1

   If it's good enough for cigars it's probably good enough for wood.

   Best regards,

   Fred

4. 
   northhouguy | Jan 02, 2010 10:37am | #4

   Oh, drat, I forgot this:

   To check the accuracy of a hygrometer, (a humidity guage), use a salt test.

   Fill a small container, (a shot glass or smaller), with ordinary kosher or table salt, (un-iodized if you've got it). Sprinkle a little water onto the salt. You don't want it mushy, just damp. Seal the dampened salt and the hygrometer in a leakproof zip-lock bag. Don't squeeze the air out of the bag, you need need it to absorb the moisture. Let things set for 8 to 10 hours. The humidity will reach 75%. Compare that with your hygrometer reading and you will know the eror in your guage.

   Look up "salt test' on the internet. There are lots of hits.

   And enjoy a Rocky Patel Robusto while you're at it...

   Fred