These pens will ruin your chalkboard painted wall. You can not get the imprint off. You will have to repaint. And the company agrees that they won't work on chalkboard paint on walls. Too bad they don't warn you on the package of their very expensive markers.from Chalk Ink company:Unless you have a very hard surface like a porcelain on steel board or a manufactured, baked surface, or a semi-gloss painted surface- you will always have that issue. Chalk paint is very porous and not hard so it is something that will need a regular touch up. It's the nature of the material.