Dampp Chaser or not, that is that question!

[Ron Nossaman]

>Because of the known relationship between spruce and atmospheric RH, RH in
>the soundboard environment will provide an accurate (although indirect)
>indicator of soundboard moisture content.
>
>Terry Farrell
>Piano Tuning & Service


"The Encyclopedia of Wood" (Sterling Publishing) lists a chart of EMC
related to temperature and humidity. It shows at 70 degrees F:
        
RH%    EMC 
 5         1.3   
10        2.5
15        3.5 
20        4.5    
25        5.4
30        6.2
35        6.9
40        7.7
45        8.5
50        9.2
55       10.1
60       11.0  
65       12.0
70       13.1

These numbers aren't specifically for spruce, but they're pretty close, and
good enough for general use.  At 60 degrees F, 50%RH = 9.4%EMC and at 80
degrees F, 50%RH = 8.9%EMC. 

For what it's worth.

Ron N