Platemaking! Need help and tips!?

Hello everyone. i'm fairly new to plate-making but my set up for making plates is a Kent: Exposure Unit that uses 4 x 8W UV Lamps and using a basic film and 300dpi screen than i expose the polymer plate with the image and the screen for two exposures than i put it in a bath of water that has bubbles bathing in the washing unit that's connected to my pad printer than i dry it down with air (paint brush tool). but it always seems to get water stains in the plate which always effects the image when pad printing is there any other way to make a polymer plates? im stuck and confused what to do