Vaseline

This doesn't come across very well at all at web size. It was an attempt to play with coloring by applying various translucent "muck" to the front lens element. Obviously, this is not something you'd want to do with a nice lens! An alternate way to get effects like this is to shoot a textured surface (vaseline smeared on a glass plate, off-white plaster wall, etc) and then combine the texture with images inside Photoshop.