National Archives conservators devoted weeks to the conservation treatment of Magna Carta, the first phase of a major project leading its re-encasement and public display. The document — written on parchment in 1297 with iron gall ink — is one of 17 surviving versions of Magna Carta in the world today, the only one in North America and the only Magna Carta in private hands. The document is on loan to the National Archives from David M. Rubenstein, co-founder of The Carlyle Group in Washington, DC. In the course of treatment ultra-violet photography revealed previously illegible writing in the text of the document that had been obliterated by water damage at some unknown time in the past. Senior conservators Terry Boone and Morgan Zinsmeister removed old repairs, filled the areas of loss with conservation paper and humidified and flattened the document.