Lightfastness Studies of Water-based Inkjet Inks on Coated and Uncoated Papers

Abstract

Instrumental color (i.e. L*A*B*) and optical density measurements were performed on coated and uncoated papers printed with water based inkjet inks using continuous binary array inkjet equipment. Lightfastness tests were performed in a QUV test chamber with Cool White Fluorescent lamps, Q-Sun Xenon Arc Test Chamber with a Window Glass Filter, and under glass at a Florida outdoor benchmark location (Q-Lab Weathering Research Service). These results were compared with two indoor exposure locations. Rank order was used to show good correlation between the various exposure methods. The results of this study generated data indicating that the lightfastness of water-based inkjet inks can be complex and dictated by the type of coated or uncoated paper used. This study also shows that inks printed on coated substrates are more susceptible to UV degradation than those printed on a bond or uncoated substrate. The development of a light stability test protocol is intended to simulate the conditions of the actual service environment. Meaningful data can be produced to better evaluate the “archivability” or predict durability of inkjet inks and substrates.