From: Debra Jacobson (firstname.lastname@example.org)
Date: Wed, 14 Aug 2002 06:39:28
Forwarded from the P2Tech listserv. There has been an interesting discussion about the subject of metals in printing ink.
We should consider some additional relevant information, however. First, during my 11 years in the printing industry, never did an environmental agency raise a red flag about barium, either in the information that I supplied to them or in any discussions held between EPA and the printing industry trade associations' environmental committees, several of which I was actively involved with.
Note also that the organo-metallic compounds that make good pigments are highly stable as they would need to be to make the inks colorfast. Colorfastness is the property of printing inks that enables the images on the products with which they are printed (magazines, inserts, etc.) to maintain their intended properties. These properties are maintained for an extended amount of time-through the printing process, through shipment to the newsstand, through the ride home with the purchaser, through the dash in the rain into the house, through the weeks on the coffee table in the sunlight, through the years in the local library and, yes, even through the decades in the landfill.
Colorfastness avoids faces that turn green or images that fade to invisibility. Barium, copper and iron are the bases of those organo-metallic pigments-in the same way that magnesium is the basis for chlorophyll (a green "pigment", albeit not a very colorfast one) and the way iron is the basis of hemoglobin (the red "pigment" that is the carrier of oxygen in your red blood cells). Consequently, the barium that is the basis of barium lithol red (magenta) pigment, and the copper and iron that are the basis of two blue (iron blue and cyan) organo-metallic pigments used in printing inks are not readily available to the environment.