Can You Glue Up Decorative Molding Against Grain on Real Wood or MDF Projects
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Q: Can you solve this apparent conflict? I’ve seen projects where decorative moldings (or even shelf supports) are simply glued on, often going across the grain. They aren’t nailed or screwed (with elongated holes or not) at all. But I’ve also read articles that state that the seasonal wood movement will cause the cross-grain glue joint to fail. What gives?

Gluing Decorative Molding When you're gluing against the grain on real wood projects, it will often fail, but it's not a problem on materials like particle board and MDF.

A: When long grain parts are simply glued, or glued and screwed, to the cross grain of solid wood, then the construction is suspect and the chance of glue line failure is high. If the cross grain is only three or four inches and the piece is in a stable interior atmosphere, then maybe you get away with it, but don’t be surprised when you don’t. We know what should happen in theory, but the perverse nature of wood sometimes overcomes the theory.

Do we know that the material was solid wood? If it was veneered plywood or any other veneered man-made bound particleboard or MDF, there is no problem gluing and screwing parts across the grain because these materials are dimensionally stable.

posted on April 1, 2011 by Ian Kirby
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