Proper Plate Cleaning
We believe photopolymer printing plates are an investment to our customers and should be treated as such. When asked “how long should my plate last?” my response is always “it depends on how well you care for the plate.” A plate is normally damaged due to poor handling or cleaning practices. You can increase the life of your investment by improving your cleaning practices.
Ink should be cleaned off the plate as soon as it leaves the press and before the ink dries. Dried ink is very difficult to remove and could lead to plate damage due to the excessive force needed to remove it. If you find that excessive force is needed to remove ink from your plates, I’d recommend allowing the ink to dry. It is also helpful to work with your ink supplier to find the proper cleaner/solvent that will loosen the dried ink to make it easier to remove.
Using a cleaner that is compatible with your plate is very important to protecting your investment. I recommend referring to DuPont’s Ink Compatibility Guide to determine if your cleaner contains solvents that are known to be damaging to the photopolymer. You can also perform a soak test with the cleaner and document physical changes the plate might experience. Use enough cleaner to keep the plate wet while wiping and dry with compressed air or blotting with a lint free cloth. Be sure that the plate is completely dry before storing or stacking. It is best to wipe the plate with 100% alcohol to remove any residue left from cleaners before printing the plate again.
Now that the correct plate cleaner has been selected, we want to ensure you are using the proper tools to clean the plates. With dot sizes getting smaller and smaller, we must be careful not to use tools that will damage them. I do not recommend the use of shop rags, nylons (pantyhose), or stiff bristle brushes. Instead, I’d recommend using a soft natural bristle brush, soft sponge (grout sponge), or lint free cloth. The best tool for plate cleaning is an automatic plate washer, since it will clean consistently and without damage.
If you want to reduce the amount of damaged plates in your facility, this is an easy first step. Following the checklist below will ensure that your cleaning practices are protecting your investment.