Prym Magic Chalk, Mark Self-Erasing.
The Prym magic chalk is self-erasing. The chalk marks can be used particularly on delicate fabrics, which cannot be washed. The chalk markings disappear after 2-3 days leaving absolutely no residue. If necessary, it can be removed by ironing straight away. Before using the chalk on new fabrics, test it, to make sure that the marks can be removed.