Street signs seem to be main targets for graffiti lately. After the graffiti is removed, the signs start to lose their color. Is there such thing as anti graffiti street signs or a method of removal that won't fade the signs?

Comments update: 14-00304812-Sign Replacement
1211 7th Street Northwest, Washington, District of Columbia
This issue has an image. You can view it here http://seeclickfix.com/issues/1348633 . signs have been tagged
By EDMONDS, FRANCINE: 12/17/2014 11:13:53 AM
12/15/14-INSTALLERS SL & EC REMOVED (2) SIGNS AND REPLACED (1) RIGHT LANE MUST TURN & (1) DRUG FREE SIGN