Mdf that has warped. How to make it straight?

[Suhagg]

Dry the disc on the convex side, place it facing up or against a heater. If it has been in a stack, the outside will become wetter or drier, and it will inevitably warp.

when it is straight, let it stand upright and paint while it is straight.

Protte

Forgot to ask, do you have any tips on other material for my interior doors? I would prefer a simple flat door that is as solid and heavy as possible yet cost-effective. It should just be painted white and get a recessed lock and pull handle.

HDF? I only found 19mm thickness and haven't seen any prices yet. Was thinking if I should glue a 19mm and a 6mm or 8mm together. Feels like its edges are more durable than MDF as well.

 

[Suhagg]

I've now received a tip about MDF lamell. Solid wood in the middle and MDF clad if I understand it correctly. No guarantee that it won't warp but should be better than MDF.

I will need to edge band the side that will be visible, but paintable ABS edge band should work well.

/edit
Proposal 2 from a kitchen manufacturer with long experience suggests glue-laminated pine. There should be boards that are 1200x2400x29mm.

His experience is that he buys them in good quality and they will definitely hold their shape if I'm careful to paint them equally and in the same session on both sides.

 

[AndersS]

It has now been so long that it is probably difficult to do anything, i.e., it is fully dried and with a curved shape, unfortunately.

 

[Suhagg]

It has now been so long that it's probably difficult to do anything, i.e., it is fully dried and with an arch shape, unfortunately.

I suspect they were a bit damp when I got them and after this time in the heat, they've taken on their new proper shape.