I am working on a coach and the interior ceiling panels are made out of a hardboard, about 3/8 inch thick and a lot like drywall. The paint is cracking, crazing, and peeling away. I'm trying to knock off all the loose stuff and feather the edges back a little, so I can Prime and paint.

I've been using a wire brush cup on a 5-inch angle grinder for all the steel work, but I am concerned that will badly gouge the hard board.

Any suggestions?

Iif you search the forum, I think someone used carbon dioxide blasting to remove paint from Masonite in the past.

It's bad enough that we make the dreaded CO2 with our locomotives, now you want to use it for restorations!

Actually, I thought it sounded like a good idea. We were looking at getting paint off a pressed metal carriage ceiling when I first read it here. But too expensive. We ended up going with wire brushes, scrapers and old screwdrivers ground to shape. Tedious but you get there in the end.

You could try various grades of "no-fill" sandpaper. Might it be easier to just replace the masonite with new stuff?

And OP, please let us know how you get on. We have a plywood ceiling to deal with soon that has the same problem.

Carbon Monoxide is the dreaded stuff. Trees and plants breathe in CO2.