Best Procedures for Cleaning Printing Plates
To achieve consistent print results from your printing plate you must clean them on an as needed basis and most certainly at the end of each print run.
Maintaining your printing plates or cliches whether they are photopolymer or elastomer in nature is of paramount importance before, during and after every run.
Unless your printing plate or engraved print sleeve is new it is vitally important that you check each of them for any contamination or damage that may prevent you from achieving consistent printed images
Whether your plate is mounted onto a plate cylinder or sleeve it may also need intermediate cleaning during the print run should any hickies, ink build up on the walls of the raised image or surface interfere with the desired result.
Cleaning your printing plates or cliches when you have finished printing is equally important should you wish to maximize the life of them and be able to guarantee that they will be able to perform as and when you need them to give the printed result that you and the customer expect
Failure to clean , protect and store your plates will result in additional costs in terms of waste, poor quality and unnecessary replacement costs that the customer will not be willing to pay for
To optimize the performance and longevity of your printing plate, sleeve or cliché the following procedures are suggested for your consideration and benefit:
In an ideal world try to remove any ink from your printing plate or cliché before it has time to dry or cure immediately after it has been run and removed from the press.
Where smaller quantities of plates or size of plate are concerned manual cleaning of your plate is usually adequate. We recommend using one of our ready to use cleaning solutions in conjunction with one of our erazor sponges or horsehair bristle scrubbing brush.
Great care should be taken not to damage the plate when scrubbing manually particularly if there is a lot of fine text or screen work. When all traces of ink appear to have been removed from the plate it should be rinsed with fresh water and dried off with a lint free cloth and allowed to air dry before storing away
To reduce the amount of labor involved you might wish to consider one of our automated plate cleaners such as our Orion Plate cleaners from Marchetti or our ACE Electrostatic vertical plate cleaners. Both types of machines can clean most sizes of plates although the ACE cleaner is intended for the largest of plates used for wide web or corrugated printing. With mechanical cleaners it is not recommended to put the same plate multiple times through the cleaner. If you have an area of stubborn area contamination that is not removed initially we recommend cleaning this area by hand .
We recommend using a lint free cloth, erazor sponge or horse hair bristled brush with one of our ink removal solutions that are formulated to dissolve as much of the ink as possible without having to resort to heavy scrubbing. Do not use a course rag or nylon brush or scrub a solid area to heavily as this may remove the polymerized surface on a photopolymer plate which will affect its ink pick up and release properties.
Any of the above products should be sprayed liberally onto the etched or engraved surface and allowed to sit for a few minutes before being agitated with one of our lint free wipes, erazor sponge or horsehair brush.
- Don’t forget to also clean the underside of the plate to remove any ink or glue residue .
- Once ink has been dissolved rinse with fresh water and dry.
- Allow plate to air dry preferably for 24 hours before wrapping and finally filing.
Never be tempted to run a printing plate, engraved sleeve or cliched with dried ink still on it. Dried ink can cause thin lines, small text or screened dots to become rigid and as a result be torn off when the image comes into contact with the substrate for the first time. If you are unfortunate enough to find your reused plates /sleeves coated in dried ink you should spray with one of our plate cleaners, allow to soak in for several minutes and wipe gently to begin the ink removal and repeat until the engraved surface is perfectly clean.
It is preferable to hang your plates and separate with a foam divider enclosed within a light proof envelope which is suitably identified with job number, product description, DOB and last rime used as a minimum
Stacking plates one on top of one another should be avoided if at all possible as this can lead to plates sticking together or crush damage
Engraved sleeves should be cleaned in a similar manner and stored upright with a protective cover
Engraved sleeves also need the interior of the sleeve and end rings to be cleaned as well to remove any build up of ink or other coatings and contaminants
It is worth mentioning that whether it is an air mandrel for your sleeve or a print cylinder for your plates the face and journals must be kept clean . Any score lines or surface damage must be repaired promptly to minimize the possibility of the final printed image being affected and in the case of the air mandrel to reduce the likelihood of the sleeve becoming stuck to the mandrel surface.
Cylinders or mandrels with journals should be checked for straightness and minimal TIR at least quarterly and both should be checked for dynamic balance prior to putting them into service for the first time.
With all plates and sleeves keep away from direct sunlight, extremes of hot and cold and ozone any one or all of these environments can and will cause drying and cracking of the engraved image making the plate or sleeve unsuitable for re-use.
Some of our more popular solutions for cleaning printing plates or engraved surfaces are as follows: