Date:Mon, 22 Jan 2001 14:33:25 EST
Betty: The answer to your question is that there is a certain % of solids that are in all offset lithographic inks. The % solids is going to be composed of the nonsolvent of the ink that is composed of pigments, film formers, resins, waxes, driers, and other additives. The % solids will depend upon many factors including the type of ink (e.g., sheetfed Vs. web), color, pigment loading, etc. I am not aware of any standard % solid ranges for these inks. As far as particulate matter emissions from lithographic inks is concerned, it is not related to the solids content. If the emissions were due to the solids, then there is a big problem because the ink is not adhering to the substrate and the ink must adhere to the substrate. There are two possible sources of particulate matter emissions from ink and they are due to ink misting, which occurs at the press when the ink is transferred from roller to roller and the other is when ink oil from uncontrolled heatset web offset presses is emitted and condenses to form a visible emission. In the ink misting scenario, it is more common with nonheatset web inks and UV inks and is more of an indoor air quality problem than an emission to the atmosphere. It can be solved through changes in formulation and I have seen the use of indoor air filtration units for some nonheatset web pressrooms. In the case of the condensed ink oil emissions from uncontrolled presses, the typical solution is to try alternative ink formulations with less ink oil, which usually are not acceptable due to production demands or an add-on control device. Changing to a UV or EB cured ink system is also an option, but can be expensive.