Even if your panel is flat, that doesn't mean it will stay that way. Follow these fool-proof steps to prevent your wood from warping.
Fasteners that help keep panels flat

Just because you've created an absolutely flat panel doesn't mean it will stay that way if it's not incorporated into your project correctly.

To keep panels stable and warp-free for the long haul, try these solutions:

  • When attaching cleats to wood panels that will be in motion--the lid of a blanket chest, for example--use a simple trick for an assembly that looks solid but allows wood to move. Screws should be just tight enough to hold the cleat against the panel. Don't glue cleats directly to the panel.
  • Fasten wide panels in place using hardware that allows the panel to move, as shown at right. Figure-8 connectors rotate slightly within their recess as the wood moves, while expansion washers create a smooth surface on which the mounting screw can slide. You can find both at Lee Valley Tools (800/871-8158 or leevalley.com).
  • Consider where your project will be used. A cabinet in a steamy bathroom must endure greater humidity extremes than a blanket chest in an adjoining bedroom. Doubling the thickness of your film finish won't totally block this moisture, but it will help moderate the humidity's impact on wood.
  • Finish both faces of a panel plus the ends and edges. This is especially important with film-forming finishes, such as polyurethane, which do a better job of repelling moisture than oil finishes. Otherwise, a panel gains moisture more quickly from one side than the other, causing it to warp. Only extremely thick finishes, such as two-part, poured-on bartop or countertop finishes, completely block moisture.