3mm basswood question

[Craig Keller]

I noticed a lot of the 3mm basswood tends to warp or bow some. What causes it? How can prevent it? Attached is the main one that does it's our arch way for our Christmas market then to the right you can view it's edge and see the bow.

 

[kcollinsdesign]

Raw wood absorbs moisture and the tension in the grain causes warping. Mounting (hide glue would be best) the panels to a same size piece of hardboard and placed in a clamp of some sort might help (normally done before cutting out the panel shape to get a smooth cut edge). A frame (more of a stretcher) could also be made and the panels glued to that and clamped. Sometime priming and painting the back side can apply a reverse tension and keep moisture out (why we paint both sides of plywood panel signs).

 

[Ron at Forest Litho]

Kcollins is right. Humidity and temperature makes the internal components of a wood board expand or contract unevenly Sealing it and letting it dry clamped flat is the only way you have a chance, but moisture can get in even thru sealant. And temperature changes cannot be sealed out. So mounting it on something unmovable is best . BUT if what you mount it on can also absorb moisture, then you can get curling from the 2 layers expanding differently to humidity and temperature. It is a tough problem that only actual trying and testing over time can solve.

 

[John_Smith]

That is the sign maker's nightmare. Spend all that time and effort on painting the perfect sign. Then after installation, it warps because he/she didn't put the same amount of paint on the back side as the front and edges.
Smaller signs are no different.
And - rattle can, and hobby paints offer no barrier to moisture. You need a good, solid paint, like house paint and primers, to have the best results. (BT-DT).