Bristol board

Bristol board (also referred to as Bristol paper or Super white paper) is an uncoated, machine-finished paperboard. It is named after the city of Bristol in the southwest of England. Common sizes include 22.5″ × 28.5″ (572 × 724 mm) and its bulk thickness is .006 inches (0.15 mm) or higher and A4, A3, A2 and A1 Bristol board may be rated by the number of plies it contains or, in Europe, by its grammage of 220 to 250. It is normally white, but is also made in different colours.