If NIST Standard Reference Materials had been available to the builders of the Titanic in 1911, perhaps the tragic sinking would not have occurred. The Titanic's steel hull was held together with wrought iron rivets. In 1998 a NIST metallurgist found that a number of these rivets contained three times as much slag-a waste product from ore smelting-than normal. The extra slag made the rivets more brittle and prone to break on impact. This may have been a major factor in the Titanic's sinking.