Przesyłam bardzo ważną publikację. Rozumiem o co w niej chodzi, nie mam z tym problemu. Muszę jednak mieć dobre tłumaczenie tekstu, którego zaznaczyłam pochyłym i wytłuszczonym drukiem, gdyż muszę wykorzystać go w praktyce, a nie chcę popełnić żadnego błędu. Z góry bardzo dziękuję.
Use of Agar Cyclododecane for Cleaning
Tests on a Frail Painting
The canvas painted by an anonymous author representing the St. Martin’s Battle (24june 1859), was accomplished with an unusual technique, i.e., using a monochrome sketching painted with few range tonalities. The preparation layers and the priming are in tempera and the executive technique is poor and uncohesive, as demonstrated by the results of the analysis carried out by Stefano Volpin.
Large areas of the painting are moisture stained probably because of its original location outdoors. The cleaning intervention carried out served to remove the non-coherent dirt from the surface and to resolve the moisture stain problem. Different tests with different materials and methodologies were carried out.
The first approach to the cleaning was difficult. Every intervention based on aqueous methods resulted in moisture absorption by the surface and formation of a new moisture stain where the product was applied. Subsquently, laser cleaning was tested unsuccessfully. After that, different kinds of rubber: (kneaded eraser, soft rubber and stiff rubber) were used. Also tested were agar gels applied with different methodologies, such as:
1. Pre gelatinized agar brushed on small areas;
2. Agar as stiff gel applied for a few minutes to have the lowest level of water;
3. Preliminary saturation of the surface with an alcohol and water mixture airbrushed on the surface prior to the agar application to prevent moisture stains;
4. Preliminary saturation of the surface with cyclododecane at different concentrations applied by brush followed with the agar application;
5. Agar reinforced with carboximethylcellulose to ‘soften’ the material and to adapt it to the painting surface.
The most interesting result was obtained using a preliminary application of cyclododecane (60% cyclododecane, 40% petroleum ether 80°-120° w/v) to stop water diffusion into the surface thus preventing moisture stains, followed by a brush application of pre gelatinized agar.
Better results were obtained during the Erst cleaning tests on areas unstained by water The cleaning was more homogenous, the surface dirt removal was effective and the paint layer was not damaged. On the other hand, on water stained areas, different results were obtained. This might have occurred because the surface was weaker so that even a minimum amount of water was too aggressive on the paint layer. When the agar gel was removed, it would rip off the paint layer in an irregular way and no uniform results could be obtained.
It is still difficult to understand how the contact between two theorically incompatible materials, i.e., cyclododecane and agar could result in an effective cleaning operation. As the cyclododecane is an hydrophobic material, it was expected that it would turn the surface Water repellent thus preventing the action of the hydrophilic agar. It could be hypothesized, that the heat brought by the agar gel allows the interaction of these two materials since it enables the cyclododecane to reach its melting temperature (58— 6I°C), so that the liquid penetrates into the pictorial layers and enabling the agar to act on the surface.
ANALYSIS RESULTS ON THE PREPARATION LAYERS
A small quantity (less than 1 mg) of ground material was scraped from a fringe area of the painting. The aim of analysis was to identify composition of ground material and to observe the morphological structure of the mixture. The sample was analyzed with a micro•FTIR and with the aid of some spot test aimed to recognize the sort of organic binder.
The ground is made by a mixture of gypsum and proteinaceous binder, possibly animal glue. The FTIR spectra shows that along with the inorganic components there aren’t anydrite or silicate but only traces of calcium carbonate. Spot tests are negative for polysaccarides, such as vegetable gums, and starch, such as flour. However, there are some traces of fats. It is evident that the gesso mixture is poor of binder; the white ground contains mainly gypsum with a very small amount of animal glue. This is, probably, the real reason of the great fragility showed by the ground.
Jeszcze raz bardzo dziękuję.