There are two kinds that look alike. The pounce is chalk The second is filled with a different white powder or Miracle Chalk. the first of chalk will wipe off easily. The second does not and can be removed with a steam iron.
The miracle chalk stays on longer. Definitely use a rubbing motion like erasing on a black board for the miracle chalk.
Miracle Chalk only is available in white. The company has not been able to find a color that will come off with steam.
There have been some reports of the blue chalk available in the Pounce not coming off when brushed.