How do I keep my poster from curling at the edges?

Poster curling almost always starts at unsupported edges. When only the corners are pinned, the middle of each edge lifts and rolls. The fix is to support the whole perimeter, not just the four corners.

• Anchor the midpoints: add adhesive putty or strips at the center of each edge, not only the corners.
• Reverse-roll stubborn curls: gently roll the poster the opposite way and hold for a minute before hanging.
• Store it flat: keep prints flat or loosely rolled in a tube rather than tightly bent.

If you want a poster that never curls, a mounted version on rigid backing stays perfectly flat because the board holds its shape.