When you are cleaning your screens first make sure that you clean the ink off the screen because the emaulsion cleaner will not work thru the ink. The other think that might be causing your problem is you never want to let the emulsion cleaner dry on your screen. If you allow the screen to dry with the emulsion cleaner on it, the emulsion will harden like you described and potentially render your screen useless.. The other tip you might use is to clean your screens with a pressure washer.