Warping MDF boards!

[JanneSjo]

Yesterday, I painted a raw MD door against the underfloor heating panel (approximately 70X80 cm). The MDF was 19mm thick, and I had read this thread before painting. I painted the back once and painted the front 2-3 times. Now I immediately see that the door warps after a day. During drying, I had it standing upright. I'll see if it straightens out when the paint has fully dried. The warping occurs towards the side I painted the most.

Very interesting to hear if the board straightens out when it has dried.

Did you paint with a brush - how smooth does it get?
(I'm considering whether to paint myself or send for powder coating)

 

[pbengtsson]

Painted with a roller to achieve the same texture as the walls (it's a hatch that should be as invisible as possible). Had painters for all the window sills and moldings made of MDF and you can see the brush marks if you're really picky.
Submitting it for lacquering is probably the most convenient option, it results in a simple and very good outcome. Not too expensive either. I've cut apart quite a few IKEA cover panels and doors and these are MDF (similar MDF I've purchased myself) and these are lacquered and do not warp, but the same painting result cannot be achieved on your own.

 

[h-man]

Lifting this up

Just to be on the safe side: is it enough to paint the back of an MDF board if you're going to wallpaper the front? Why would it be convenient to have it lacquered (assuming the entire board should be lacquered) compared to painting it yourself? No one sees the back, so it can look however, right?

 

[raveper]

Should also be possible to solve with some primer before wallpapering.

 

[Suhagg]

Anyone else with tips on how to keep MDF straight?

I have 30mm MDF to be used as interior doors.