To minimize the volume of waste generated, press cleaning can be modified to an organized three-stage cleaning process to reuse wastewater or waste solvent (depending on type of printing ink used). Once the ink is drained out of the ink lines, off rollers, out of the ink pan and back into the ink container, the equipment can be cleaned.
Multi-stage cleaning processes involve three steps in which the water being used becomes cleaner with each step. In the first step, semi-dirty water (previously used for interim rinse water) is used remove the first, heaviest layer of ink and soil on the press and press parts. In the next step, cleaner water (previously used for the final rinse) is used in the interim stage to remove more ink and dirt. In the final stage, fresh water is used to clean the remaining small quantities of ink and dirt from the press parts. In this way, each bucket of fresh water is used three times before becoming wastewater. Multistage cleaning can significantly reduce the amount of both water and solvent used in press cleaning.
Stage 1: The majority of ink is removed using water/solvent that has been previously used for step 2 cleaning.
Stage 2: Ink, left after the first stage, is removed using partially dirty water/solvent that has been previously used for step 3 cleaning.
Stage 3: Any remaining ink is removed by clean water/solvent.
When the water/solvent used in Stage 1 becomes too dirty to be effective, it may be filtered or mechanically treated on site or appropriately disposed off site. Stage 2 cleaning fluids eventually become Stage 1 cleaning fluids, Stage 3 becomes Stage 2 and fresh water/solvent is used for Stage 3.