EMC and working time for soundboard panels

[Farrell]

You can measure that fairly easily by weighing a few samples of spruce cut 
to panel thickness. I did that a while back, and although I don't remember 
the numbers exactly, I found that I can keep a 6.0 - 6.5% MC spruce panel 
out in my 35% - 40% RH shop eight hours with no significant changes in MC. 
Obviously a little higher RH is going to affect MC more rapidly.

Either weigh samples of  spruce or measure the panel across the grain. 
Measure the panel width at initial conditions, dry it down and measure when 
it stabilizes, and then test it for a day - take it out of the hot box and 
let it sit in whatever climatic conditions you can reproduce in your shop 
for eight hours (or how ever long you will need to do what you want to do) 
and measure it. The measurement method really does work quite well - pretty 
easy to observe how the panel is changing.

Terry Farrell

----- Original Message ----- 

> Does anyone know from their own experience what the approximate working 
> time
> is for a soundboard panel before it starts to appreciably change its EMC. 
> I
> realize it depends on the RH and temperature, so let me be more specific. 
> I
> know that I can maintain a 6.2% EMC by simply keeping my shop at 30% RH 
> and
> between 60 and 70 degrees F.  While I have no trouble keeping my
> conditioning box at those numbers, getting my shop below 40% and stable is
> difficult--though I can keep it around 45% relatively easily.  If I pull 
> the
> panel out of its 30% RH box into a 45% RH room, approximately how much 
> time
> do I have to work with it before it will move above 6.5%?  At 45% RH and
> those temperatures listed above, the EMC would be more like 8.5%.  I'm 
> just
> trying to get a sense.  Also, approximately how much time is needed back 
> in
> the box to return it to 6.2% (assume 70o).
>
> David Love