Stabilising fibreboard

[Dave Plowman (News)]

I'm replacing the headlining on the old car - it's a foam backed nylon glued to a fibreboard former and the foam has disintegrated. I've sourced the correct fabric, but on removing the liner it was slightly distorted. I've wetted it and dried it out under weights and it appears to be back to the right profile again. But what would be best thing to 'seal' it with or whatever to stop this happening again?

[Tom Woods]

I've used PVA glue on my car headlining boards to fix them and strengthen them. remove all the loose foam dregs first with a stiff brush and then give it a couple of coats of slightly watered down pva. It may take a couple of days to dry.