What Warped My Lattices?
Issue: Issue 294
Posted Date: 2/7/2012
I have built a series of two sizes (approx. 16-1/2" x 12" and 12-1/4" x 9-1/2") of lattices using half-lap joinery. The lattice pieces are all 1/2" square and oriented so that the side grain forms the surface. This is because the lattices are used as a bread cutting board atop a 1-3/4" high box with a rabbet along the inside top edge to accommodate the entire lattice. The idea, that really works, is that bakers of their own bread (or buyers of artisan breads) keep their kitchen countertops free from breadcrumbs using this cutting board. The lattice spacings form 1" squares.
My problem: Some of the lattices have bent/warped towards the notched side. This means that the long side can be warped in one direction, while the short side is bent a little bit in the other. I built three of each lattice size this past summer out of well-cured maple and beech. I used normal white wood glue and treated the finished product with food-safe mineral oil. While they sat in my shop for a couple of months through somewhat different weather conditions the lattices were all fine. After that, they were part of a display at a local store; I do not know under which temperature and humidity circumstances. Nevertheless, upon their return to me, they are all more or less in the above-described condition. Is this purely a combination of temperature and humidity? Might they slowly return to their original flat state? Are there assembly or preparation tips and tricks I might use in the future to build these lattices for a wider range of environmental conditions? -- Michael Popp
Tim Inman: What a neat project! My wife is an award-winning baker -- and has the ribbons to prove it. She would love to have one of these cutting boards. As the resident test pilot/guinea pig for her creations, it would help me to avoid issues which occur in the line of fulfilling my duties, too. I'm guessing your troubles track from environmental sources. I'm suspecting your projects were proudly displayed in either brightly lit sunny store windows, or brightly lit enclosed glass showcases inside the store. In either case, your project got cooked. Going from humid summer to "proofing ovens" for display is probably what caused the damage. You did finish all sides, top and bottom of the wood, right!? There is a chance your wood will relax and normalize back to its original shape. There is a better chance it will go back by halves -- never quite getting it perfect. We'd love to see pictures!
Chris Marshall: If I'm understanding your design correctly, the warped lattices were sitting inside their rabbeted boxes but were not otherwise fastened in place. I wonder if pinning their corners or edges down would improve their chances for stability over time and a wider range of environmental conditions. But, given how thin the cross-sections of the slats are, and the swings in humidity and temperature they experienced, possibly not. If your design could allow for a "fixed" lattice, it might be worth a try. I'd also be curious to learn what the outcome would have been if those lattices were made from riftsawn or quartersawn material instead. There is an enigmatic quality to wood, isn't there?