Soundboard Panel Drying Schedule

[Farrell]

Having played a little bit with some spruce and my hot box, and made a few observations, I can see that it is not going to be a straight-forward process of drying a spruce panel down to a targeted equilibrium moisture content (EMC). I have observed that when there is very little contrast between EMC environmental (atmospheric) conditions and the MC of the wood, it will take a long time (weeks?) for a spruce panel to come into equilibrium with its surroundings.

So, no sweat, just stress the system. Increase the contrast between environmental conditions in the hot box and the MC of the wood, i.e. raise the temp and lower the RH beyond those required for target EMC conditions. The question is how much? If my target is 6% EMC, where should I set the atmosphere in my hot box? That of 5% EMC? Lower?

How do you'all  monitor MC of your panel?  I plan on using a sample piece of spruce placed into the hot box along with my panel that I can weigh and get a direct MC of it. If you raise the temp and lower the RH in the box beyond that required for your target, you will end up with the outside portion of the panel with a MC below target, and the center of the panel above target. 

Seems to me that the best schedule would be to cook it in conditions that exceed those required for targeted EMC for some optimal period of time, and then let the panel sit in atmospheric conditions targeting desired EMC for another period of time (a week?).

How do you soundboard folks juggle this hard-to-put-your-thumb-on process?

Terry Farrell