Otterbein Calcidur Natural Hydraulic Lime NHL 3.5 is used to create mortar and plaster that can be used for most building and construction applications. The powdered lime uses moisture to set and is ideal for use for pointing, re-pointing and rendering. It is suitable for use on brickwork, block work and stone and is fast setting. Hydraulic Lime is ideal for use in particularly harsh conditions including sea-defence walls.