How to keep poster board from warping?

Sharon Henry
by Sharon Henry

I want to make a sample board to see what my wall could look like with a unique stamping technique. After painting the board it dried warped, bad. What do I do now?



  10 answers
  • Kathy Gunter Law Kathy Gunter Law on Feb 26, 2021

    You can affix it to another thin board. I used to temporarily do this on my kid's school projects before painting, then remove when dry. The water in the paint causes the paper to warp.

  • Maura White Maura White on Feb 26, 2021

    I would add some some 1x1 inch wood pieces to all of the edges so that it can be fully spread out with some weight. Leave it like that for awhile. Putting out in the sun and heating it just a bit can also help flatten it out (ironing by sun).

  • Cynthia H Cynthia H on Feb 27, 2021

    Hi! Posterboard does that. I usually tack it down or weigh it down until it's dry. Keeping it flat helps also. Then I frame it or mount it to hold it smooth. Poster frames are fairly inexpensive in stores, if you don't want to make a frame. Measure so you know what size you're going for. Good luck!

  • Lindsay Aratari Lindsay Aratari on Feb 27, 2021

    You could weight it down with heavy books or weights

  • Sharon Henry Sharon Henry on Feb 27, 2021

    I vote (this time) for the ironing by the sun. It is workable now.

  • Dee Dee on Feb 27, 2021

    Use Painters tape in the corners to keep it flat


  • Libbie B Libbie B on Feb 27, 2021

    Once you wet it there tends to be warping. Try lying it flat with books for a week or so and it should flatten out.

  • Vimarhonor Vimarhonor on Feb 28, 2021

    Hello. Water in the paint can cause the warping. You might wish to try to reflatting it using your household iron with a protect layer of parchment paper.

  • You might try using a piece of foam core or balsa wood instead to do your test on.

  • Lifestyles Homes Lifestyles Homes on Mar 07, 2021

    I agree, foam core board.

    poster board warps on its own, just from high humidity.