Comparisons of Grains (IMAGE) University of California - Santa Barbara Caption The polymer-covered spherical glass beads used in the experiments. The grains at the top have a very thin coating and no cohesion; those at the bottom have a much thicker coating and are cohesive. Credit UC Santa Barbara Usage Restrictions For Use with Credit License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.