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 ... Found on http://en.wikipedia.org/wiki/Bristol_board