Out with the old art, in with the new: after printing with photo emulsion, here's how to make sure you (your silk screen, actually) will live to print another day.
Clean all the ink off the silk screen. Use a pressure washer if you have one.
Mix a solution of equal parts household bleach and water.
Pour the bleach solution onto the surface of the silk screen.
Scrub lightly with a nail brush or soft-bristled scrub brush and let sit for five minutes.
Scrub the entire surface on both sides.
Rinse with water.
Repeat until all the emulsion is removed.
Hold the screen up to a window or bright light and tip to view it at different angles.
Scrub until it's clean no matter at which angle you view it.
Allow to air dry fully before storing.
Use the pressure washer (in a pinch, a garden hose) to wash the screen out. If you don't have any kind of a pressure device, washing will take longer and you'll scrub more. You can buy commercial products for this purpose, such as CPS Screen Wash, but bleach works fine and is less expensive. Make sure to get the emulsion off the taped edges of the screen as well as off the middle.
Wear gloves and goggles: photo emulsion is toxic and bleach is caustic.