Perhaps it depends on the brand of spray chalk, but whatever the spray that others have used around here isn't much different than paint. There was one race in our local park where the organizers put down huge, obnoxious, course markings all over the park including on some decorative stamped concrete road crossings. The marks were still visible after a year! If you decide to use this stuff you might want to do a few test marks to check that the particular brand you are using will actually disappear after a short time.