<html> Ron, <x-tab>        </x-tab>If I correctly understand what you are doing with your sophisticated :-) setup, you are looking for a change not necessarily a specific number from your meter. Correct? Do you feel that you can adequately state the moisture content of the wood from an instrument designed to measure the air simply because it is against the wood and trapped under a blanket? What would happen to the measurements if you introduced , say, a 6" air pocket around the hygrometer instead of having the blanket on top of the meter? Do you think that the readings would be different? the environment you create with the space heater under the piano is not necessarily the same environment above the board . Would you agree? If you measured the MC under and over the board they would surely be different, right? Could it be possible that some degree of instability is possible because of this? I know the board is relatively thin but without air circulating around the top could there be potential problems with uneven rates of contraction of wood fibers? Would this cause future problems with cracks or is this all semantics and nothing to worry about. Thanks for your indulgence of my random thoughts! Greg At 04:52 PM 8/30/2002, you wrote: <blockquote type=cite class=cite cite><blockquote type=cite class=ci= te cite>Ron,         If one were to strive for and "for the sake of discussion" achieve that absolute accuracy how long could the board be expected to stay that way after it is removed from the "hot box" for working? If I took the board out and got a little side tracked and didn't get to gluing my perfectly formed ribs on until say an hour or two later ... am I too late? do i need to start the process of drying it down all over again? Greg Newell</blockquote> Greg, I'd say, presuming the need for absolute humidity control, that you would be assembling the soundboard in a rigidly humidity controlled room, and you could take as long as you wanted - if you didn't breathe too much. In the real world, it depends on a couple of things. How much string load are you counting on the panel supporting, and how much the ribs? What's the difference between your target temp & RH% (indicating MC in the panel) and your work area temp & RH%? If you've dried your board to say, 6% MC, and your shop is 70° at 30%RH,  then you have lots of time. Eat lunch. Take a nap. If the shop is 80° at 75%RH, then you'd probably better consider drying it down again. As an experiment some years back, I made a little MC gage out of a cross grain strip of new soundboard spruce, with a thin strip glued cross grain to one surface after I'd cooked it dry in the oven. Then I mounted it on a base so it cantelevered out over the base on edge. I marked on the base, where the end of the strip was while it was still dry. It bowed nicely when it re-hydrated. I started drying it down with my panel when I did soundboard replacements or repairs to see if it would make a dependable MC gage. It doesn't seem to be bad at all once you get it reasonably calibrated. I still use it as an indicator of whether or not I've dried the panel long enough after I reached my target temp & RH, for the wood to have caught up. I found that what we've been told is true. Wood does seem to absorb humidity faster than it releases it, but it's tough to tell how quickly it's doing either in the shop. So the best way I know of to tell if your board has been out of the box too long is to check your home made MC gage and see what it says. Ron N </blockquote> <x-sigsep></x-sigsep> Greg Newell <a href="mailto:gnewell@ameritech.net" eudora="autourl">mailto:gnewell@a= meritech.net</a></html>