Method to Measure the Sub-Visible Ink Content of Low-Consistency Whitewater Streams, 1996 Process & Product Quality Conference Proceedings

Hugh P. Lavery

Garden State Paper

The “ERIC” infrared reflectance method of measuring sub-visible ink content in recycled papers is a useful tool for evaluating deinking process performance. However, the frequently-used extension of the ERIC technique to pulp pads involves both theoretical and practical problems. An alternative method of sample preparation has been developed at Garden State Paper to provide an accurate and reproducible measurement of the ERIC ink content of pulps and filtrates. The method involves producing lightweight “sheets” of filtrate solids at a minimum of two different grammages on microporous cellulose acetate filters. The infrared reflectance of each film and filter background is then read using the ERIC method as implemented on a Technidyne reflectometer. Each set of reflectance measurements is then resolved into scattering and absorption coefficients by the simultaneous solution of the Kubelka-Munk equations. An ERIC ink concentration in milligrams of ERIC ink per liter of filtrate may then be calculated based on the absorption coefficient and filtrate consistency. This method has been useful in addressing a variety of deinking issues, including measuring the ink removal efficiencies in washing, flotation and papermaking, and testing the effectiveness of various potential deinking chemicals.