Instructions for using the stouffer gauge to accurately figure out the exposure time for your photopolymer plates): The Stouffer gauge is a reusable piece of continuous-tone film that you should use to test photopolymer plate exposures. Place the Stouffer Gauge in contact with a 1” x 6” strip of plate material (after you peel off  the plate’s protective plastic cover). Then expose the plate.

You’ll have to guess the first exposure time because that varies depending on the equipment that you use. Start with the exposure time listed on your plate’s tech data sheet. For exposure times, please keep in mind that these times are for commercial photopolymer platemaking equipment. Any alternative photopolymer platemaking devices may have very different times and you’ll have to experiment more to find your ideal time.

Also check the plate's tech data sheet for the Stouffer value you’re trying to hold during exposure.

For example, the 94FL has a Stouffer value of 18. Make sure that the exposure used with the Stouffer Gauge hardens the plate for all the numbers up to and including #18. If you goal is #18, and #19 and #20 start to harden during your exposure time, then your exposure time is too long– decrease the exposure time. If your goal is #18, and #17 hardens but #18 washes out on the test plate, then increase the exposure time.

You most likely will have to expose several different test plates at several different exposure times to find the perfect exposure. Since the Stouffer gauge is small, you won’t waste much plate material in the process.