Ivoroid

Unless you’re talking about guitars built before World War One, all binding and heel caps are made of celluloid nitrate, which is created by dissolving short cotton fibers in nitric acid. Celluloid has been around for over a century and is most commonly used to resemble natural materials such as ivory, pearl, and even tortoiseshell. True ivory has grain that runs all in one direction and so ivoroid, which is meant to simulate the look of real ivory, is extruded with fine lines to give it a more authentic appearance.