A T shaped screen panel seal strip for use in spanning between screen support rails in a vibrating screen is disclosed, which has a plurality of notches therein in registration with the screen support rails so that the strip can be placed over either new or existing screen support rails (after having been cleaned of any cushioning cap material). The strip can be metallic or a plastic material. The method includes retrofitting existing screens with a new sealing strip by first removing any cushion cap material and then placing the T shaped seal strip over the support rails.