Madonna attacked by fungus
Fungus infested artwork on paper is especially difficult to treat. Paper is a perfect medium for the growth of fungus, when high humidity is present. The fungus cannot be removed, as it has spread its hyphae net into both the porous paint layer and the paper.
The Madonna portrait, an unfixed pastel of an unknown artist from the 19th century, showed the kind of damage described above. The size of the pastel is 313 x 255 mm. The painting was built on two layers of different papers, which were glued together before painting. It has been kept in storage in a solander box (storage box) together with several other art works in old acidic mounts. The pastel seemed to be stable and mounted with paper strips in all four corners to the secure pastel within the mount.
The two layers of paper started to delaminate and the fact that the pastel is not fixed led to a few scratches and losses in the surface. The surface also appeared to carry some dirt in the form of white particles.
Restorations suggestion and investigation
First it was necessary to secure the two delaminated papers by gluing them back together. Secondly it was necessary to consider if the particles could be removed with a brush under the microscope. Finally the pastel required a new acid free mount, because the acid from the old mount was accelerating the deterioration process of the pastel.
While examining the pastel under the microscope it turned out that the white particles on the surface were conglomerations of fungal hyphae. These conglomerations were the only part of the fungus damage you could see with naked eye. But it also turned out that fungus had penetrated the whole surface and hyphae were to be found in a fine mesh penetrating the structure of the pastel.
Fungus requires high humidity for growth and finds an ideal medium in paper fibres, animal glue and parchment; art works on paper are therefor often affected by fungus damage. However, it is unusual to find a pastel in art-collections so heavily damaged, and it is always a concern to a collection to find infested works of art.
The most important step of treating a fungus infested object is the disinfection to stop the growth and deactivate the spores of fungus. This is a tricky treatment, because it is not possible to know exactly when and if all spores are devitalized. First the disinfection with ethanol was applied by spraying it over the pastel. The second step took place in a small chamber with ethanol vapours for 30 hours, ensuring sufficient time for the ethanol to affect the fungus. Afterwards the pastel was allowed time to ventilate for four days before the treatment was continued.
The woven mesh of fungus hyphae all over the pastel could not be removed without losses to the pastels surface. Thus it was decided that only the conglomerated parts of hyphae, which could be seen with the naked eye, were to be removed mechanically with a slightly moistened brush. This process took place under a microscope. The two delaminated papers were glued back together to secure the pastel.
After treatment the pastel was mounted and hinged in a new mount. For the storage it was placed on its own in a solander box with reference to fungus written on it. The pastel is now stored in a climate stable storage area to reduce the risk of a new infestation, reactivation of the old one and the possible spreading of fungus spores to other parts of the collection.
The other objects that had been placed in the same box as the fungus infested pastel were also inspected under the microscope and when fungus was not found they were dry cleaned. Then the objects were mounted in new, acid free mounts as there were concerns that the old mounts might have become infested with spores.