[Woodcarver] Laminates

[Ivan Whillock]

Bonnie,

Yes, when two pieces of wood are glued together it is called a lamination. The joints formed by gluing straight edges of wood together are called butt joints.  

 A board cups to the sapwood. The wood also has a tendency to cup into the carved part.   There are several ways to deal with the cupping that takes place.  One is to flip-flop the individual boards so that they alternate, heartwood up on one board, sapwood up on the other.  (I've had great success with this method even on extremely wide panels, and is the one I normally use.)  Another is to carve from the heartwood to the sapwood. Thus the tendency of the wood to cup in the direction of the sapwood is counteracted by the opposite tendency of the wood to cup to the carved side.  (This method works best with single boards that are not laminated.)  The third method was developed by Bill Judt, I believe, because he prefers to carve with the sapwood up.  Therefore he cups the initial plaque which will then straighten itself by cupping into the carved section.  (Bill explains this method in his books.)  

Wood expands and contracts with changes in humidity.  A thick part of the wood will expand and contract slower than a very thin part.  Therefore, if you have an extremely thick portion adjacent to a very thin portion, the thin portion may shrink faster, creating tension between the two, and crack.  Therefore, a rule of thumb is to leave more wood than you take away.   So, if you are carving a two-inch thick panel, the deepest part of the carving should be slightly less than halfway down--just less than an inch. 

That said, the environment can make a difference in what depth you can carve and still avoid cracking. Wood that is outdoors is more susceptible than wood in a temperature/humidity controlled environment.  If the panel floats in the door frame, the changes in humidity are not extreme, and the finish is maintained, cracking can be controlled even when you slightly break the "rule of thumb." If the panel is to be outdoors, however, you may want to follow it.

In any case, wood "moves" as it gains and loses water, and carvers use these  methods and more to allow that movement to take place without damaging the carving. 

  ----- Original Message ----- 
  From: Bonnie Schroeder 
  To: woodcarver 
  Sent: Sunday, November 20, 2005 10:36 PM
  Subject: [Woodcarver] Laminates


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  Wonder if anyone has information on Alder or Cherry laminates.
  I'm doing a deep relief carving on a 3' x 6'10" door.  The top half of the door is to be carved as an insert.  The depth will be 1 1/2".  I  will carve four levels at 1/4" each, leaving a 1/2" uncarved.  Is this  sufficient to prevent warping/cracking?    When they join two 12" wide boards together, is the process called lamination, or should I be asking  for something else at my local woodworking shop?

  Bonnie Schroeder
  Victoria, BC
  Canada



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