i mark just the one line with white appliance paint has bush in cap . as for a fully degree damper you can do what Glen said i done the same thing with white paint then go over it with a dry rag then when almost dry go over it with a damp clean rag with thinner on it. but this was done on black oxide damper like ATI and Fuildamper .TCI if you want to get fancy paint damper thats fully degreed paint black with four coats of black paint then shoot white paint wipe clean with a 3M rubber squeegee off let dry wet sand out with 1000 then clear