Warped Fiber Board

[LowNote]

I have some .093" volcanized fiber board that has warped or rather cupped. How can I flatten it back out?

LowNote

[big_teee]

Try getting it wet.
Then apply some heat with the heat gun and flex it until it is flat.
I've done that, then leave some weight and a board on it overnight to help shape it.

[jonson]

Dampen or mist spray the cupped side (concave side) with water and place a piece of paper that side as well and clamp between two flat wooden panels and justy leave it to dry out. You can do the same with cupped timber.

[LowNote]

Thanks for the help!

LowNote

[SonnyW]

Dampen or mist spray the cupped side (concave side) with water and place a piece of paper that side as well and clamp between two flat wooden panels and justy leave it to dry out. You can do the same with cupped timber.

That's pretty much what I did and it seemed to work okay. I wet the whole thing (I soaked it a lot) and put the material between a plastic cutting board which was well supported against a 2 x 12 pine board, and then stacked up about five or six phone books on it on top for weight for a couple of days and it seemed to flatten out okay after a week outside. Maybe not 100% perfect, but okay to use. I did use copier paper between all the outer layers. The phone books were freebies from my front porch, but one was a heavier McMaster Carr catalog.

[jonson]

The reason I said wet the cupped side is to allow that side to stretch a bit and let the dry side pull it round. A lot of stacked timber tends to cup because the moisture has dropped to the bottom of the plank so by allowing moisture the other side you can even it out and push it back. If you get a sheet of cupped mdf or plywood just wet the cupped side and lay it dry side up in the sun for while and it will pull back.

[Randall]

Clothes iron works, too. Works on amp boards as well. Let it cool under weight. Takes just a minute.