Eventually, it probably would rust the screen, but since they are building seperate enclosures anyway, a week or two won't. I myself am only using it as a quick fix, while the auto mister comes. Still one of the absolute best quick fixes EVER for humidity. I've tried foil. and paper towels in the tank. and I still had to mist the tank upwards of 6 times a day. Damp towel? none, and humidity stays at 70%. Very, very nice fix.