Glossary A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Term of the Day: Metamerism The phenomenon by which colors match when viewed under one type of light (e.g.: daylight), but differ when viewed under another type of light (e.g.: fluorescent). Zahn cup An efflux viscometer consisting of a small cup with a hole in the bottom and a handle so that is can be dipped into the liquid to be measured. The viscosity is recorded as the time required for the cup to empty through the hole. Zinc dust Ground zinc metal, gray in color, used in metal primers. Zinc Oxide A commonly used pigment which is capable of killing mildew. Zinc white A common white pigment, zinc white is a brilliant white synthetically derived from the metal zinc.