A method for measuring the agglutination of ball‐point ink in a narrow brass tube

Ball‐point ink is a heterogeneous, viscous multi‐phase fluid. It consists of resins, solvents, diluents together with solid pigment and filler. The fluid is contained in a thin polyethylene tube which acts as a fluid reservoir continuously supplying the ink to a narrower brass tube. The latter has an inner diameter of about 0.8 mm and holds a small ball at its tip. During storage for long periods, agglutination of the ink takes place in the brass tube and around the ball as well. The rate of such agglutination is strongly related to the environmental conditions. In the present work, a technique is developed to measure the thickness of the agglutinated ink film by means of a microscopic examination. Hence the thickness of the deposited solid layer on the internal periphery of the brass tube will be estimated. Furthermore, factors affecting the agglutination process will be investigated and methods to decrease or even to eliminate that phenomenon will be put forward.