Warped board problem

Hello, dear fellow artists!

I have a little problem with my MDF boards recently. When I purchased them(they were cut to measure for me), they were absolutely fine and straight. Still are. But when I mounted an oil painting on paper on it, it looks like it warped, slightly. Not too much, but it is not laying absolutely flat on a table. I use an acrylic medium to mount the painting.

Is there any way to fix that? I tried to put it under weight, its a bit better, but still not straight. Is it ok to sell it like this or would it pose a framing problem later?
Thank you!

I have read about birch boards and MDF boards warping and the usual suggestion is to paint both sides of the panel before using. Not having actually tried this myself, you might paint a blank MDF panel on both sides with acrylic paint and see if that helps to straighten it out. Best wishes with this.

Thank you, Patricia! Will try it and report back :slight_smile:

What thickness mdf board are you using? I’ve never tried mounting an oil painting on paper onto one of these, but imagine that it might benefit from being 4mm thick. Or 3mm if, as Patricia says, you paint the reverse. I’d paint the reverse anyway, irrespective of thickness (and the edges).

I use 3mm board, will try to paint on both sides, if that didn’t solve the problem, next time I will buy a thicker ones.

Hi Lena,
Painting a coat of acrylic Matt medium on the reverse side of the panel might cure the problem of warp, as it may balance out the stresses. If not, 6mm board would be better.

Hi Joseph, thank you for your answer! Yes, I did paint acrylic medium on the reverse and put the board under the weight, that seems like solved the problem. I now preparing my new boards like this, before mounting. But next time will choose 6mm boards to avoid all this …

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Yes as others have said here:
Use thicker boards
Paint/prime both sides from the start, don’t wait for them to warp.
Try to store them in a dry place, warping is usually caused by humidity. Maybe a closet with a de-humidifier.
Some will warp any ways, the larger they are the more prone they are to warping.
Some aritist’s have gone to aluminum panels for this reason but the cost is higher.

Thanks for the tips, David!

As mentioned here, it’s always important to add size to both sides of the board. For larger panels, I place two (or four) supporting strips of wood to the back, almost in a cradled way, this ensures the panels stay completely flat. It’s an old method.