Leonardo Da Vinci's Codex Atlanticus, the largest collection of drawings and writings by the Renaissance master, is being destroyed by mould because of lack of restoration funds.

The mould has stained and damaged many of the 1,200 sheets in the codex, kept at the Ambrosian Library in Milan and bound in 12 volumes. The damage was discovered by Carmen Bambach, an American scholar from the Metropolitan Museum in New York.

She said that there were “a large number of stains” and “swellings” in the paper of the codex. She raised the alarm by informing Monsignor Gianfranco Ravasi, then the head of the Ambrosian Library, now head of the pontifical Council for Culture at the Vatican.

Restorers were called in from the Opificio delle Pietre Dure, the state conservation institute in Florence. However, since there was no funding available, four Florence restorers — Garbriele Coccolini, Cecilia Frosinini, Letizia Montalbano and Roberto Boddi — travelled to Milan at their own expense. Ms Frosinini said that they had carried out “minimum emergency restoration to try to limit the damage and prevent it getting worse”.

Mr Boddi, a climatologist, said that the problem had arisen partly because the volumes were consulted by visiting scholars and exposed to the atmosphere and humidity.

Various types of mould, in colours ranging from black to red and purple, were identified on the drawings, which include sketches for some of Leonardo's most ingenious inventions. They date from 1478 to 1519.

The codex was rebound between 1968 and 1972 after an earlier restoration. Experts said parasites were destroying the cellulose in the paper and even the glue used in the bindings.They said that the restoration would be a lengthy and costly process involving drying the volumes, cleaning the pages and removing the spores of mould and analysing them, before treating the codex. Ms Frosinini said that this “precious sick patient” would then have to be preserved “in different conditions” to ensure that the mould did not return.

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