For centuries, seamen searched for a coating that would stop the damage caused by marine organisms. They used concoctions made of pitch, tallow, sulfur, horse hair, sand and ground glass. Lead sheets fastened with iron nails were tried in the early 18th century, but the lead quickly corroded away in seawater. In the late 1750's, the British Admiralty started using copper sheathing plates fastened with iron nails. Although the nails corroded, the copper plates stood up well. The final breakthrough came with the use of copper nails.