Monday, March 26, 2007

Gluing Up Seats

I have always avoided gluing up seat blanks for my chairs. I figure that the time saved using a single blank and the security of not having a joint in the seat easily made up for the extra expense. But recently I have been using butternut, and the availability of wide pieces is slim. For seats where the grain runs side to side, I have found that I can match the grain so that the joint is virtually invisible and actually gives the seat a more striking appearance.
Anyone who's glued a tabletop has come across the technique of alternating the growth ring direction on the boards. It helps to keep the final piece flat. If you think about the growth rings as seen in cross section (or end grain), they will move towards straightening out. By alternating them, you minimize this tendency versus compounding it. Imagine a panel that curls like a potato chip versus one that has some waves. Well I've found that by using this technique on my chair seats and carefully matching the angle of the grain where the joint is, that the carving "erases the joint"
If you look at the photo of the end grain above, you'll see that I've accentuated the growth rings with a pencil to show their orientation. To make this joint disappear, I try bring the boards together where each of their growth rings is at a similar angle. When this is done correctly, the image that the grain reveals when carved will be seamless. It's as if you've created a new way for the tree to grow! I always arrange the board that will be carved for the deepest part of the seat so that it has the outer part of the tree facing up (growth rings down). This gives a lovely "topographic" look to the rings as they descend into the deepest point. Also, by using a narrower board at the back of the seat, I ensure that the joint is located in a heavily carved area (avoid passing the joint through any future spindle locations) and therefore helping to obscure it. Taking the boards from the same plank to match the color helps in unpainted work You can see the finished results in the bottom photo. Rarely does anyone know that the seat is a glue up and often, once told, they cannot find the joint.

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