No do not use a bristle brush, as there is a coating on the screen.  You will take off the coating and you will see a discoloring on the screen.  You can take a  shammy cloth dipped in hot water and get the crayon off that way.  Do not rub in a circular motion, only up and down.  Continue to do this with the hot water and the shammy till all of the crayon is removed. There is a slight possiblity you will need to replace the screen if the crayon is imbedded deep into the screen, as to get it off may cause a discoloration. Good Luck, and let us know how you made out with this screen.

"Those who do not know their opponet's arguments, do not completely understand their own".