EPK, which is how most people refer to the material Edgar Plastic Kaolin, is a secondary water-washed kaolin that is mined in Florida. Its popularity is due to its plasticity and white-firing properties, especially when compared to other American-sourced kaolins. It has excellent casting properties. It is not plastic enough on its own for throwing bodies, so it should be augmented by a more plastic kaolin or by a plasticizer like bentonite or hectorite when you use it to formulate a throwing body.

EPK is considered by many to be the best North American kaolin for use in suspending glazes as it tends to produce a smooth thixotropic slurry. 15-20% will normally make the glaze gel slightly, so when a piece is immersed in the glaze and removed, it drips very little and the wet glaze layer stays in place for the time it takes to dewater. Since EPK is very close to theoretical kaolin chemistry, it will substitute for any other kaolin that can make the same claim.