21 April 2006
Reason for treatment
Examine and document treatment and condition extensively.
Stabilize Surface consolidate where necessary. Stabilize substrate. Alter old plaster mount for new display.
The object is mounted in plaster of Paris set into an inner wooden box frame covered with a wood veneer. The front of the frame is glazed. The plaster of Paris mount is flush with the paint surface completely covering the original arricio(mud plaster). The plaster of Paris mount appears stable.
The arricio appears to be overall stable.
The intonacco appears overall stable but there are several cracks across it.. There are detaching areas between arricio and intonacco, mainly in the perimeter area of the fragment, identified by a hollow sound on gently tapping the surface. There are losses to the surface due to abrasion and impact damage. There is also some powdering. Losses have occured near the edges where small section appear to have been broken off and had been reattached. Some previously detached pieces appear to have been misaligned. Beeswax and plaster fills are in the gaps between the reattached pieces and the main fragment. There is yellow staining and small craquelee cracks in the perimeter areas, most likely a result from the drying of the plaster mount. There is evidence of salt efflorescene near the bottom edge.
The paint layers are flaking in many areas and there are many losses. The blue and green frit are particularly fragile due to loss or shrinkage of the binding medium. Hairline cracks are also visible across the entire paint surface. Surface coatings applied during old treatments over the cows and the white ground have attracted dirt and discoloured. In places they have shrunk pulling away the paint layer from the ground.
There is also loose dust and other fine particles on the surface.
The object was thoroughly examined under a microscope. Observations on ancient painterly techniques, past treatments and present treatments were recorded individually as technical information record on hard copy (see envelope for detailed information). A photoshop file detailing the objects condition, observations on painterly technique, past and most current treatment is also available on memory stick.
The object was lightly dry cleaned with low suction vaccuum cleaner. The old coatings, most notably apparent around the perimiter in the upper register and on the cattle bodies were identified as carnaubawax, soluble nylon and celluloce acetate.The carnaubawax was removed with White Spirit (composition variable - petroleum distillate) The soluble nylon could only be removed were it had been applied over the cellulose acetate by swelling the acetate and mechanically removing both coatings. There remain traces of soluble nylon over the black paint of the cow in the lower register.
Loose paint flakes were reattached with 12% w/v Primal B60A (acrylic) in deionized water applied with White Spirit (composition variable - petroleum distillate) used as wetting agent. Powdery areas of intonacco were consolidated with several applications of 1.5% Paraloid B72 (ethyl methacrylate copolymer) in Acetone (propan-1-one/dimethyl ketone)/Industrial methylated spirits (ethanol,methanol)(1:1). Fragile areas of arricio were consolidated with 20% Primal B60A (acrylic) sprayed on over White Spirit (composition variable - petroleum distillate used as wetting agent.
The old wooden box was removed but the old plaster mount was stable and was retained for most parts. Only the upper edge was cut back mechanically with a minidrill to enable the painting to be displayed very closely underneath EA37978. As the plaster edge at the top was very thin after cutting it back a stainless steel plate was fixed to the top edge of the new display box to strenghthen that edge. The collar of the old plaster mount was reduced mechanically with a minidrill to leave 5mm of the arriccio exposed. Fragile areas of the exposed arricio(mud plaster) collar were consolidated with 12% Primal B60A (acrylic ) applied with Industrial methylated spirits (ethanol,methanol) used as wetting agent. In order to give the a smooth display surface to the old collar Polyfilla Plaster repair, a ready made acrylic paste, was applied over the old plaster of Paris. A paste of microcell glass balloons in 20% w/v Paraloid B72 (ethyl methacrylate copolymer) in Acetone (propan-1-one/dimethyl ketone)/Industrial methylated spirits (ethanol,methanol)(1:1) was applied to the arricio where it would be in contact with the Polyfilla Plaster repair paste to act as an interface and to enable future reversibility.
The object was encased in a new made-to-measure display box made from plywood.