Manufacturing Publications

ELIMINATION OF TOXIC CHEMICALS FROM BLANKET WASH BY A LITHOGRAPHIC PRINTER

SUMMARY

A medium-sized lithographic printer eliminated toxic TRI listed materials from the blanket wash solvent blend.

PROCESS MODIFICATIONS

Traditional blanket wash, with a volatile organic compound (VOC) content of approximately 6.5 pounds per gallon, was replaced with a blanket wash containing 5.2 pounds per gallon. The chemical content and physical parameters of the new cleaning solution compared to the traditional blanket wash are provided below.

*based on common blanket washes

The replacement blanket wash was not a simple drop-in replacement. Drying and cleaning rates are slower than the traditional blanket wash, which contained trimethylbenzene. Machine operators had to become accustomed to using the new blanket wash without compromising print quality or increasing press clean-up time. An eighteen-month test and transition period took place before the new blanket wash was fully industrialized at the company.

RESULTS

In 1993, the printer generated in excess of 9,000 pounds of TRI listed chemicals from use and disposal of the blanket wash. By substituting an alternative blanket wash blend, the TRI waste generation from blanket wash dropped to less than 1,000 pounds in 1994, and reached zero in 1995.

There was no direct cost saving to the printer by replacing the blanket wash. The cost of the new solution is approximately 25 percent more per gallon than the traditional blanket wash. Also, more waste liquid must be disposed due to a lower evaporation rate. However, benefits include reduced environmental reporting, fire hazard, VOC emissions, and worker exposure to toxic chemicals.

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