Chalk lines on composite deck? Our contractor used a chalk line to fault where the supports...

Our contractor used a chalk line to fault where the supports where on earth on our deck, but the lines have not come past its sell-by date. It has rain quite a bit and I of late tried scrubbing them next to a brush. They are getting fainter, but you can still see them. Any ideas on how to catch them off?
Answers:    Use acetone or some staple polish remover... Use pour some on a cloth and rub...
Try to use alcohol and see if that will work alone with the brush.