Absorption studies of coldset ink components into paper

There has been a lack of direct methods to measure ink absorption from printed paper. Absorption of visible ink pigments can be studied by applying microtomes and light microscopes but other equally important components ink oils and resins are invisible. As ink oils and resins are organic materials, there are no means to distinguish them from other organic material such as wood fibres even with the most sensitive analytical equipments. This paper represents one solution to the problem above. A suitable oil soluble inorganic tracer element was introduced to the ink and the penetration of the oil was detected by applying instrumental neutron activation analysis (INAA). The paper was split to several layers and the activation analysis was performed to the layers. The penetration of the ink pigment could be detected by analysing the copper compound of the cyan ink pigment in the same paper layers by ICP-MS technique.