Magic Whiteboard is completely erasable. Any dry whiteboard marker ink will rub off even if left for days. Each sheet can be used more than 20 times. With the Magic Gridboard, ink will rub out with ease during group work sessions (up to 3 hours) but this version has been designed so that the ink becomes more permanent after this period. The reason for this is so that the content is not lost when the sheets are folded. Using a damp cloth or whiteboard eraser the ink can still be erased if left overnight. Each sheet can be used more than 10 times.