Abstract: A system of components for preventing the application of graffiti to property includes one or more sensors and a signal transmitter at or near the surface to be defaced, and signal receiving means for actuating a mechanism in the spray apparatus or at the surface to be protected which will enable prevention of the surface targeted for defacement. One embodiment of the invention includes a signal receiver in the spray canister which actuates an electromagnet to move a plug in the marking material delivery tube to a flow blocking position. A second embodiment of the invention includes a signal receiver in the spray canister coupled to a rotatable magnet for rotating the upper end of the delivery tube away from the spray nozzle thereby breaking the path through which the marking material travels from the spray apparatus to the target surface.