Replies

1. 
   HowardAcheson | Sep 04, 2011 06:53pm | #1

   Short of encapsulating the wood in epoxy, any finish will allow water vapor (humidity) to pass through.  At best, a finish will somewhat slow up the water vapor transfer.  Application of a coat of dewaxed shellac will further slow up water vapor transmission.  This means that the wood will expand/contract whenever the relative humidity of the item's location changes whether you use oil based or waterborne finishes.

   The mere finishing of the wood using a waterborne finish will not materially affect the EMC of the wood.

2. 
   joinerswork | Sep 05, 2011 08:33am | #2

   Rich,

   That's a tough problem, for sure.  If you can just wait til humidity goes down again to assemble the doors, that will be your best option.  Trying to suddenly and quickly change the moisture levels in the stock is fraught with bad possibilities, warping and cupping amongst them.  The difficulty is in attaining a uniform level of "dryness" throughout the material. If you must press forward right now, I'd resize the stock before trying to shrink it in a few days.

   (On a side note, we went without doors on our cabinets for months after we moved into the house.  Somewhere, we have a picture of our oldest child sitting in the middle of the kitchen, surrounded by the pots and pans he'd pulled out of the cabinets.  The wife laughs about it now.  It only took her about ten years to get to that point.)

   Once the door frames are assembled, if the mortise and tenon joints are well fitted, you ought not to have much of a problem. The glued joint will hold things in place at the corners, and the end grain of the rails (where the most rapid moisture transfer takes place) will be buried,and sealed with glue.  If the living space is conditioned (a/c in summer, humidified in winter) the avg humidity will not fluctuate so much.  And a finish will retard moisture loss/gain somewhat, so that by the time shrinkage is really occurring, swelling is just around the corner, so to speak. 

   In future, you might want to minimise the problem, esp if you know the wood is one that moves a lot, by using quartersawn (edge grain) or riftsawn stock for these members rather than flat sawn or slab sawn (face grain) stuff.Qtr sawn stuff is a lot more stable.

   Ray

1. 
   draco_myst | Sep 05, 2011 11:42am | #3

   Thanks Ray, I must admit that I also worried about trying to force the moisture level down quickly. I also regret that when I bought the stock many years ago, I had no knowledge as to the excessive movement of Lyptus. If I had known I would have never used it for this project. I did cherry pick from the stack when I made the door frames choosing the straightest grain that was as close to quartersawn as I could find for those parts. The panels got the less desireable flatsawn material, and for those I alternated the end grain (up-down-up-down) during glue-up

   When I made the joints, I used the Leigh FMT Pro jig, so the joints are not only well fitted on thickness, but on tenon width as well. In fact, they got tighter on width during the summer (the jig makes the mortise slightly larger than the tenon, and the expansion filled that gap). This means that the rails moved out from the center in BOTH directions, and I cannot align either edge.

   Re-cutting the inner edge of the rails is a nightmare since the front face to edge corner is rounded over, and this was done prior to slotting for the panel, so re-rounding after re-cutting the edge is impractical. The slotting removed the bulk of the locating surface for the roundover bit bearing.

   The living space is NOT air conditioned, and if what I have been told by others is true, the parts will still move even after finish is applied. If this were any other species of wood, I would rely on the axial grain of the stile to hold the glued rail against expansion, but I am frankly worried that 3/64" expansion over 5-1/2" is simply too much, and either the stile will crack, or the joint will fail. (Opinion?)

   I think that what I may end up doing is extending the width of the mortices (if necessary) so that I can align the outer edge after first removing 50% of the total amount of rail expansion from the outer edge. This re-cut isn't exactly easy either as there is a relief cut in the face on the outer edge that makes the frame look thinner than it is which I would have to redo. But it is still easier than re-cutting the inner edge. My thinking is that right now, the parts are sized to be correct when dry, and have the maximum mismatch when it's humid. Removing 50% of the expansion would make them correct at some point in between with only half the mismatch when dry or humid. When I do the glue-up, I will not glue the inner tennon (I have double tenons on the wide rails), or the inboard half of the mating faces. Once glued, I think that this will mean that the outer edge will remain flush year round, and the inner edge will be flush in the spring and the fall with slight mismatches when it is very dry, or very humid. This should also prevent any type of stile, or joint failure since the rail can still move. I don't see any other way around this problem.

   It has been ten years for this project already. Waiting 5 months for the frames to dry again won't sit well with the wife ;)

1. 
   joinerswork | Sep 05, 2011 05:47pm | #4

   Sounds like you have a workable plan for moving ahead.  Are the inside corners of your frames coped together? that will help hide the movement you are experiencing.

   Ray

1. 
   draco_myst | Sep 05, 2011 06:42pm | #5

   No, the frame design was "borrowed" from a Scandinavian design china cabinet that we have. The rail has a flat end face with an integral tenon, and the entire interior perimeter of the frame was router cut with the stiles & rails clamped together to leave a transition radius at each of the corners where the stiles & rails meet with most of the curve cut into the stiles. The difference is that they used narrow rails, and Teak (really GOOD Teak), whereas I used wider rails, and Lyptus. The wider rails resulted from a desire to have upper doors with an arched top rail (The left hand door of each pair of doors has a top rail that starts out wide on the left, and gets narrower at the right, and the right hand door is the mirror image). The movement will show, I'll just have to live with it. But what was your opinion on the cross-grain glue-up? If I let it all dry, and glued it as-is, wouldn't it be risky?

1. 
   joinerswork | Sep 06, 2011 09:34am | #6

   Risky...Depends on the fit ofthe mortise and tenon joints, length of tenons.  Gluing up dry, the next swelling cycle the joints will hold the wood from expanding (at least at the end) if the joint doesn't break loose, the wood fibers may get squashed together (compression set).  Then next shrink cycle, there might be a slight chance of a split developing.  On a 5" wide (on one end) rail, I don't think there's a problem.  If, as you are planning, you do not glue one of the tenons, any movement will take place there, but only over half (the unglued half) of the width.  It'll be pretty minimal-  1) end grain of rail enclosed, and coated with glue, 2) wood surface coated with finish, 3) half the width restrained from moving at all.

   Ray