Known as a Sand-Lime Brick. Made from sand, or crushed flint, mixed with a hydrated lime, approximately 1:8 with little water. The damp mixture is moulded, under great pressure, to form the required brick shape. The green bricks are loaded into an auto-clave and subjected to high steam pressure for 7 or 8 hours. Can be made as Engineering; Facing, and Common Bricks.