Leonardo da Vinci's Codex Atlanticus, the largest collection of drawings and writings by the Renaissance master, has been infiltrated by mold, officials said Friday. The extent of any damage is not yet known to the roughly 1,120-page Codex containing his drawings and writings from 1478-1519 on topics ranging from flying machines to weapons, mathematics to botany. But officials say any conservation measures will be very expensive and there are no funds for the work. The Codex is kept in a vault at the Biblioteca Ambrosiana, where temperature and humidity are constantly monitored. Mold was first identified in April 2006 by an American scholar, and confirmed by the conservation experts from the Florence-based state conservation institute, Opificio delle Pietre Dure. Until the scientific analysis is done the extent of the damage and its cause will not be identified, said the Opificio's deputy director, Cecilia Frosinini. Frosinini said the mold could be the result of factors including exposure during any exhibition or study, or the unintended consequence of a 1968-72 restoration. No documents of the restoration exist but various techniques used at the time might have exposed the documents to future damage, she said. They included the practice of varnishing pages with glue to give them shine and make them more attractive. The Codex was last on public exhibition in 1998 at the Biblioteca Ambrosiana. More recent exhibitions in Zagreb and Rome with models of flying machines and other contraptions made from Leonardo's drawings in the Codex were been hugely popular.