Replies

1. 
   SteveSchoene | Jan 05, 2007 08:54am | #1

   It should be at the same moisture content that it will be when it moves to its permanent home.  That implies shops should be heated and cooled similarly to houses. 

   HOWEVER:  Properly designed furniture will accommodate changes is moisture content.  Going from say 12% (air dried--ie. poorly conditioned shop) to 7% will cause fairly significant changes in the width of boards.  But those changes shouldn't ever cause any wood to split.  That's what frame and panel construction, table top mounting clips and other methods to allow for wood movement are for. 

1. 
   Rich14 | Jan 05, 2007 04:54pm | #2

   dispeak, To add to what Steve said, the "ideal" moisture content for wood to be used for furniture is about 7-11%. But as he said, that alone is no assurance that furniture will not self destruct as it is exposed to the possible extremes of relative humidity that a normal living environment experiences. All construction must use techniques that accomodate wood movement or eliminate it. Frame and panel construction accomodates movement in solid wood. Applying a thin veneer to MDF or plywood (as for a tabletop, for instance) eliminates it (the top will not move relative to other parts of the table construction). Rich

2. 
   frenchy | Jan 05, 2007 05:00pm | #3

   dlspeak,

     No one single item will promise perfection.. Wood at 7% moisture is not a warrantee nor does wood at 12% moisture promise failure..

    It's a matter of the design and application allowing for changes that occur normally.  Right now the moisture level in my house is around 4% in the summer the moisture level might appraoch 80%

    It's  a matter of accomidating that change which is what determines if wood will split.

3. 
   JohnWW | Jan 05, 2007 06:53pm | #4

   The ideal moisture content for wood when you are building the furniture is a MC that is in equilibrium with the humidity in your shop.  This is generally achieved by bringing the wood into the shop weeks in advance of starting the job.  If the wood is not acclimated and thus gaining or losing moisture, it will be changing in dimension as you are working with it, which makes it very difficult to do good work.

   Once the piece is finished, it is at the mercy of whatever environment it is placed in and must, as others have already explained, be designed to expand and contract with sesonal changes in humidity. 

   Plan on a minimum of a 1/4" in movement for each 12" of width in panels and table tops.  If the wood is especially dry when you build the piece, typical of winter shop conditions in New England, you will need to leave room for the panels to expand.  If your shop is humid, the allowance will be for the panels or tops to shrink.  If the humidity is mid range when you build, leave room for both expansion and contraction.

   John White, Shop Manager, Fine Woodworking Magazine 

1. 
   jeanlou | Jan 07, 2007 09:38pm | #5

   ''Once the piece is finished, it is at the mercy of whatever environment it is placed in and must, as others have already explained, be designed to expand and contract with seasonal changes in humidity.''

   Johnww

   To illustrate what you said, we produced a shipment of millwork in our shop and shipped it from eastern Canada to British Columbia via truck in the wintertime, driving through Canada. The majority of the millwork experienced serious expansion/contraction problems because the truck was not climate controlled and the trip took almost 7 days. We solved the problem by driving south into the US, crossing the country and then driving north to BC, limiting the time that the millwork was exposed to extreme conditions. This approach solved the problem in the subsequent shipments.  JL