When a dry erase marker mark on a dry erase board sits too long it can be difficult to get off. To remove, simply take a dry erase marker and scribble several times on the stuck-on mark. After doing this, the old and new marks can be erased or wiped away. The new mark moistens and loosens the old mark from the board.
Yooz dry erase marker to remove old dry erase marker marks on a white board