Bristol board (also referred to as Bristol paper or super white paper) is an uncoated, machine-finished paperboard. Bristol generally describes drawing paper that is pasted together to form multiply sheets. Illustration board has 100% cotton drawing paper mounted on both sides of heavyweight board. Bristol board may be rated by the number of plies it contains. The surface texture is either plate or vellum. Plate finish is as smooth as glass and is very good for pen and ink. Vellum (or kid) finish is a medium texture more appropriate to friction-based media such as crayon, chalks, or charcoal. A third finish engravers or wedding may be used for formal engraved wedding invitation.