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printech, August, 2002
Re: Metals in Printing Ink


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From: Robert Fricke (rafricke@esmillennium.com)
Date: Wed, 14 Aug 2002 09:20:24


Some more thoughts on barium.

The TCLP threshold is 100 ppm. When barium is complexed with organics and some inorganics, it is difficult to extract the barium. TCLP uses a mildly acidic environment to encourage the barium (and other metals) to leach out just like in landfills. So we have found that it takes 10-100 times the barium actual concentration to release 100 ppm of barium into the TCLP extract used for threshold determination. It is possible for some barium-red lithographic inks not be TCLP positive. Therefore, actual barium or other metal concentrations, in at least lithographic inks, are not reliable indicators of TCLP characteristics. Always do the TCLP test to verify waste red lithographic inks. In fact, we have found that when the red ink is mixed with other inks as wastes, which is the general practice, the composite waste sample is not TCLP positive for barium.



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