Pollution Prevention Tips for Printers

A Publication of the Georgia Pollution Prevention Assistance Division

Georgia printers form a diverse group, consisting of varied printing technologies and methods. However, all must deal with waste generation and disposal. There are three major areas of commercial printing that generate significant waste: press cleanup, printing, and image (plate) making. By analyzing the processes that generate waste, printers can often reduce the amount of waste generated and raw materials used. Pollution prevention techniques can often help printers reduce waste, reduce the costs of environmental compliance, and improve the environment, while increasing the profits and making their plant generally safer for workers.

Cleanup

Equipment cleaning between printing jobs is the major source of hazardous waste for many printers. Waste ink mixed with cleaning solvents, dirty solvents, and rags or wipes are commonly hazardous due to solvent content. Often the inks are not considered hazardous until hazardous cleaning solvents are mixed with the ink during or after cleaning. Before using solvents to clean press components, remove as much leftover ink as possible by scraping. Unused inks can sometimes be saved for reuse when that particular color is needed or it can be blended to produce another color. Even if the ink must be disposed of, it is less likely to be hazardous.

After scraping away the ink, less solvent will be needed to clean the press. Instead of using a toxic or hazardous solvent such as xylene or MEK, less hazardous solvents can be substituted. Mineral spirits, N-methyl pyrrolidone, or some alcohols can be substituted. Water-based cleaners may also be useful in press cleaning; many printers clean critical press parts in ultrasonic cleaners using only hot water and detergent. Solvents should not be used on noncritical surfaces. Press exteriors and floors should never be cleaned with solvents; there are many water-based solutions that can be used.

Rags and wipes are major sources of air pollution and hazardous waste. Rags used to clean presses are often soaked with solvent. Wet rags and paper wipes should be stored in a closed container after use. The solvent can be recovered by spinning the rags in a centrifuge; paper wipes can also be spun. Rags that appear only damp can contain significant amounts of solvent. It is common to recover one gallon or more of the solvent by centrifuging 10 gallons of rags. The recovered solvent can be reused for cleaning, reducing both the amount of solvent that must be purchased and air emissions. Some speciality cleaning solvents can cost $15 per gallon; recovery and reuse can save money. Often this "dirty" recovered solvent can be used to clean very dirty, ink-laden parts initially. Clean solvent can be used for final cleaning. Using solvent in two-stage cleaning can reduce new solvent usage by up to 50% and cost nothing to implement.

Rags that have had solvent removed are less expensive to clean. Printers that have installed centrifuges have found that laundry services will sometimes reduce prices for rag cleaning.

When used solvent becomes too dirty to use for any type of cleaning, distillation or filtration can be used to recover clean solvent from the dirty solvent. Small solvent stills to handle as little as one gallon can be purchased to recover solvent. Cleaning solvents can also be used in parts washer sinks; many of these are equipped with filters. Filter-type solvent sinks are also very good at extending the useful life of solvents.

Printing

Printing inks can also be a source of air pollution. Inks are now available that contain no solvent or reduced amounts of solvent. Water-based inks are available for screen printing, flexographic, gravure, and lithographic printing. Low solvent inks such as soy-based are commonly used to print business forms and newsprint. Besides solvents, inks can also contain toxic metals. Printers should contact ink vendors for blends with reduced metals and solvents.

Image or Plate Preparation

Image and plate preparation can generate significant amounts of waste. The major focus of waste reduction is to CONSERVE chemicals and materials. Use just enough process chemicals to get the job done right. Internal recycling of process chemicals and water can also reduce waste and cost. Key chemicals and materials to consider for conservation in the prep area are: photographic solutions, film scrap, fixer, developer, intensifiers, reducers, proof and setup waste paper, proofing inks, flexographic resins, plates, screens, cleaners, photographic rinse water, and other solvents.

Pollution Prevention Check List for Printers

• Use solvent solutions with lower volatile organic compound (VOC) content and lower vapor pressures to reduce air emissions, solvent usage, and costs.

• Replace hazardous solvents with nonhazardous or water-based.

• Use water-based inks if possible.

• Keep solvent and ink containers TIGHTLY covered when not in use.

• For small-use solvents, use pump or spray bottles that keep solvent from evaporating.

• Use automatic blanket washers.

• Use recirculating parts washers instead of rags to clean ink trays and removable rollers.

• Rags should be laundered and reused.

• Wet rags and wipes should NOT be air-dried or placed in dumpsters.

• Cloth rags and disposable wipes should be centrifuged to recover solvent for reuse.

• Spent solvent can be recovered by distillation for reuse as new solvent.

• Keep used rag storage containers closed and tightly sealed.

• Schedule print runs during the day from light colors to dark to reduce the need for cleaning.

• Run similarly setup print jobs one after the other.

The Pollution Prevention Assistance Division (P²AD) is available to help Georgia companies reduce waste and increase profits through pollution prevention. Services range from telephone assistance to on-site evaluations and consultations. The service is free, confidential, and non-regulatory. For more information call Jancie Hatcher at 404.651.5120, 800.685.2443 in Georgia, or e-mail at p2ad@ix.netcom.com.