I use these chalk markers to write on a black slide notes. The colors are striking and intense, they have a good opacity, fast drying. Compared to my former white chalk marker which has just cost a lot for a piece of that of Marshal Office are more economical. I've also tried on a glass board and they look quite great. Easily removed with a damp and dry cloth. What is not on the package is that the markers should be kept horizontally, otherwise the colors are pale. Recommended!
