Recently I undertook to build a dining bar for a client that will separate the kitchen from the dining room. I made it from random lengths and widths of 1-1/4 cherry. The pieces are jointed and planed, biscuited and glued. I used pipe clamps and cauls to keep it rigid and flat. After the glue dried I hand-planed the surface till it was flat, then applied one coat of varnish to the top (but not the bottom, which need additional planing). Since then it has developed a distinct warp along its longitudinal centerline that is evident top and bottom.
What should I have done differently? Just as important, once I replane the top surface of the bar, what should I do to prevent a second warping?
Thanks for any help
Replies
The primary cause of the warping is that the panel is only finished on one side.
While no commonly used wood finish completely stops the wood from gaining or losing moisture, most finishes slow the movement of moisture considerably. On your top the wood on the back of the piece has gained or lost more moisture than the finished side leading to uneven dimension changes between the two faces which caused the top to cup.
Either stripping the finished face or applying the same finish to the back of the top will allow the two sides to reach the same moisture levels after a week or two of sitting and the top will flatten out by itself. It is also possible however that the warpage has been extreme enough that some of the fibers in the top have crushed and will not fully return to their former size which means that some of the warpage is permanent and the top will have to be replaned.
The best approach would be to remove the finish from the front of the top, I would use a cabinet scraper rather than a chemical stripper, and then sticker the top, so air can get at both sides, in an environment similar to that in a ordinary house. The top will, after a few days to a week or two, flatten out at least partially and with luck fully. After it has stopped moving you should then replane as needed and then finish both sides equally in one session.
John White
John, thanks for the great information and the recommendation. I had guessed it was something along those lines. I'll implement the remedy right away.Paul
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