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You could try ironing it mate... works a treat with the plastics
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That is a possibility, but only as a last resort. Ironing with a wet
towel followed by clamping has been suggested. The construction/
fastening of the squares makes me lean toward trying that last. I have
it clamped now near the furnace. Hopefully, the heat will take any
moisture out while clamped.
Thanks!
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Too much heat will damage the fibres, plastic is best.
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Remove the warp, AND THEN dry it out. IE, put moisture INTO the board.
Clamp and force to shape. Let it take the shape, then DRY the board.