Press return ink should be stored in sealed 55-gallon drums and properly labeled to optimize the potential for reuse.
Press Return Ink is ink that remains in the ink tray at the end of a press run. In a perfect world, there would be no ink left over after the completion of a job. However, most presses are currently designed to require a minimum amount of ink in the sump to function properly. Therefore, printers have to manage this unique "waste" ink. Instead of disposing of the ink as a waste or in some instances, a hazardous waste, inks can be saved and used on future press runs or re-blended and used for other jobs.
Best Management Practices & Pollution Prevention
The best way to reduce ink waste is to minimize press return ink by using only the amount of ink needed for each job. Estimating software or ink estimation training for pressmen can help to accurately determine how much ink is required for each job.
Re-blending (a.k.a. reworking) press return ink can increase efficiency, reduce ink purchases, and reduce hazardous waste generated. Reworking ink can be done by blending press return ink with virgin ink of the same color, mixing press return ink with virgin ink to make new colors or mixing press return ink with other colors to make a new color or black ink. Software and equipment are available that can help printers blend ink and reuse press return ink.
It is important to know the components of a container of ink, especially if the printer produces different types of product, such as film or foil as the inks for these are not interchangeable. These inks have different gloss, adhesion properties, and heat resistance; as a result ink contamination is a concern. It is important to maintain documentation of the contents of each batch of ink used in a mixed-ink log book. Careful labeling and inventory review of press return ink should be carried out.
For access to vendors who may supply alternative materials and equipment, see the PNEAC Vendor Directory.
Press return ink that cannot be reused or reworked may be considered a hazardous or special waste. Careful records documenting the additives and adjustments made while mixing and handling the ink will help in the determination of whether or not the press return ink is hazardous. If the hazard class of the ink cannot be established based on this information, independent laboratory testing using approved U.S. EPA test methods may be necessary.
Health & Safety
Appropriate hand and eye protection should be worn when handling inks. A splash apron is also recommended. Due to various solvents and additives commonly found in inks the material may be an irritant if exposed to skin.
Since some inks may contain pigments that are comprised of metal compounds that may be hazardous, measures to protect employees from absorption of these metals (such as wearing gloves and other PPE) should be taken. Employees who handle the ink should never eat, drink, smoke or make contact with sensitive membranes (eyes, nose, mouth) after handling inks and before thoroughly washing hands.