The fragments of the illuminated manuscript Quedlinburger Itala, dating from the 5th century and the oldest extant biblical manuscript, had been preserved glass since 1875. Mold attack occured. Prepared pigment samples were tested for their resistance to commonly used fungicides and solvents (formaldehyde gas, ethylene oxide, UV tradition toluene). The colours found on the manuscript included brasil wood mixed with red ochre, indigo plant green plus a mineral carrier, yellow ochre powder gold and a white. Paint samples were prepared according to medieval recipes. Considerable colour changes were found ant it is advised that until more is known about the reactions illuminated manuscripts should not be disinfected. The leaves are still preserved between glass plates, but distance from them by the insertion of paper absorbents, to permit air circulation. Diagrams, photographs and colour plates references.