 Paint @-@ like gels ( which are dispensed from pipes and can be transported through portals ) impart certain properties to surfaces or objects coated with them . Players can use orange Propulsion Gel to cross surfaces more quickly , blue Repulsion Gel to bounce from a surface , and white Conversion Gel to allow surfaces to accept portals . Only one type of gel can be effective on a certain surface at a time only . Some surfaces , such as grilles , cannot be coated with a gel . Water can block or wash away gels , returning the surface or object to its normal state . 
