Things You'll Need
Sponge or cloth
If you have ever worked hard on a poster and suddenly made a mistake with the marker, you might have wondered how to save your masterpiece and save yourself from having to start from scratch. With a little patience, and a marker-remover pen, it is possible to do just that.
Dampen a clean sponge or cloth. Do not saturate the sponge. Douse the sponge with a small amount of rubbing alcohol.
Gently dab the problem area with the sponge. Do not wipe back and forth as this may cause the marker to smear. Dabbing the poster board will lighten the color of the marker. Allow the poster board to dry thoroughly.
Swipe the marker spot with a marker-remover pen when the poster board is completely dry. Marker-remover pens are available at hardware stores and some craft-supply stores. Be sure to select a pen suited for your type of marker -- water-based or permanent.