Pile of Boxes and Warping Lid
I went to an event that had a marvelous door prize: 18 boxes made by my friend Sean. These were intended as prizes for a tournament, but there were only 23 entrants total, so almost everyone went home with a box. These boxes were made from some of the ash purchased at the same time as my stock pile.
As a member of one of the tournament teams, I came home with one of these boxes. It sat in my front hallway for the last four days, looking pretty. But now that the heat and humidity have returned to normal levels, the lid and front side are starting to cup away from the box. In part, I think this is a case of grain orientation; in part, a case of excessive moisture. I've taken the box into the basement and lightly misted it with water on the cupped sides. I've also cracked the lid to get the inside drying faster. I don't know if either of these actions will help, but it's worth a try.Now I'm worrying about the benches I'm making, and hoping that the better treatment of my lumber (painted ends and tarp over top) will mean less moisture content. I did some research to see if you can figure moisture content without a meter, and found a method for calculating moisture content with an oven and a scale.
Perhaps I'll try it before building my benches.
posted by rookster at
9:58 PM
5 Comments:
Rookster,
How are the battens attached to the top of the box lid? The problem might be partially cased by the method of attachment. Let me know and I'll do my best to explain what happened.
Chuck Bender
Hi Chuck,
The battens were attached with glue. It looks to me like they are no longer attached accross the entire length (the boards were glued heart side out, and cupped away from the battens, pulling the board away from the batten). I was thinking about driving a cut nail through and clinching it over.
Also, as an update to the post, I've left the lid to the box open for the past weeks, and the wood has mostly returned to the original position. I'm thinking this is a case of uneven moisture content that might be fixed by applying more or different sealant -- I'm told the current finish is a single coat of BLO.
Thanks.
P.S. I would love if you would comment on what happened and how you would fix it.
Karl,
Applying more sealant might slow things up a little but it won't resolve the problem. Short of encasing the wood in epoxy, it will always try to absorb and release moisture.
The biggest problem you have is with the battens. Since they were glued across the grain, they were restricting the natural movement of the lid. Ash is a pretty tough wood and when it "wants" to move, it will. That's why the battens are no longer completely attached across the top. The lid has broken the glue joint. You're lucky the lid didn't crack, actually. If it had been made from some other wood, you may very well have seen some serious cracking.
There are several ways to address the problem. The first way would mean a fair amount of work to the top. You'd need to remove it from the box and then remove the battens. Cut the top in half along the grain. At this point you can make up new battens with sliding dovetails on them. Cut matching sockets in the two halves of the top and reglue with the battens in place. You'd need to make sure the dovetails on the battens are haunched so that there is room inside the sockets in the lid for expansion and contraction. Also, you want to make sure there is no glue that actually makes contact with the dovetails.
The second method is a lot less work. Remove the battens and clean up the old glue. Drill through the battens creating slots that run with the grain of the batten (and across the grain of the lid once the battens are in place). Re-attach the battens to the lid with screws. The slots will allow the lid to expand and contract naturally while the batten holds it straight. Three screws in each batten should be sufficient. You should not glue the battens. Only attach them with the screws.
Leaving the lid open for a while once the piece is in your home is also a good idea. From the picture, the box was outside. With the lid closed, there's less moisure exchange. Remember, wood is always trying to reach equalibrium with it's surroundings. If the box is closed, the inside surfaces of the box will absorb and release moisture based on that closed environment. The outside will keep trying to level off with what's happening in the room. Letting it acclimate to the room where it will "live" is always a good idea. Once the battens are re-attached as I laid out above, and the piece has acclimated to your room, you shouldn't have too much trouble with it in the future.
Good luck and keep us posted on what happens.
Chuck Bender
Thanks for the thorough and excellent answer, Chuck. I certainly will post what happens. I'm leaning toward the tougher of the two solutions, and it is low on the project list right now, so it might take a while...
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