help a beginner measure mc in wood with confidence

[Gene Nelson]

At one time in my past the work I did required me to measure dew point 
accurately. Had a clear glass device where a calibrated thermometer was 
inserted and tubes where air was run countercurrent with CO2 gas from a 
cylinder filled with liquid CO2.
Increase gas flow, monitor temp as it falls and record when water drops 
appear on the air side. This was checking dessicant status and the dew 
points were usually -10c or lower.
I am certain that there is a way to get rh from dew point??
Gene

----- Original Message ----- 
From: "Jude Reveley/Absolute Piano" <juderev at verizon.net>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Saturday, August 16, 2008 6:45 PM
Subject: Re: help a beginner measure mc in wood with confidence


> Moisture meters like any other device we use are only as handy as they 
> work. There are some good ones on the market but are calibrated to measure 
> boards of a specific species. Usually the sampling takes place at about 
> 3/4" within the board, which as I figure puts us at about 3/8" past the 
> other side of a typical soundboard panel. You can spend some dough to have 
> Wagner custom calibrate one of their pinless jobbies and they'll work 
> about as good as any of the other methods that have been posted. Choose 
> your poison.
>
> My beef is more with the hygrometers. I bought one of those fancy Luffe 
> instruments along with the certificate. By the time I figured out the darn 
> thing didn't move out of a range of 35-40%RH, it was too late to return. 
> At least I can use the certificate for shop toilet paper.
>
> Jude Reveley, RPT
> Absolute Piano Restoration, LLC
> Lowell, Massachusetts
> (978) 323-4545