Kovács Petronella (szerk.): Isis - Erdélyi magyar restaurátor füzetek 13. (Székelyudvarhely, 2013)

Puskás Katalin: Kísérlet a vörösbomlásos bőr kezelésére, avagy epizód egy 19. századi fotótartó mappa restaurálásából

impacts affecting it (e.g. fires) and by events (e.g. archaeological excavation, removal, restorations), but to give back the appearance it probably had originally. Hence, we did not reproduce on the stones we used colour changes caused by external factors. On the other hand, we did reproduce without exception the ‘mistakes’ made when the motifs were created, namely the unwarranted use of particular colours. We regarded the conveying of the original colour range and mode of execution as the principal goal. After studying Gyula Rhé’s notes and archive photographs of the excavation work, we performed a complete diagrammatic recording of the motifs of the original mosaic floor now in the lapidari urn of the Hungarian National Museum. The laying of the stones was done in the studio using transparent film which had been drawn on earlier: the film was cut to fit the different parts to be executed. The geometrical system of the mosaic’s motifs presented good opportunities for this, since around every element in the design ran a contour consisting of a double row of black stones. Certain parts, however, we made in one piece, cutting them into smaller pieces only after the mapping of the entire surface. By turning the film over and sticking onto it a layer of gauze, we made a stable and light temporary support for the laying-out work. On this we set out, and stuck, the mosaic pieces with their top part pointing downwards. For this we used a mixture of 1 part polyvinyl acetate emulsion and 3 parts methyl cellulose, which ensured strong holding but which could easily be removed from the surfaces of the stone pieces using cold water. The laying out of the motifs was a task that took four persons eight months.

The original grounding of the mosaic floor in Room 20 was disturbed in a number of places, but was still there. We therefore had the opportunity to take examples before making new grounding to be put on. On the basis of investigations, dolomite of different degrees of fineness and brick rubble had been used as filler in the limey binding material for the grounding in the tablinum. For the building of the copy, we used an injectable mortar containing lime, metakaolin, and powdered marble — and also a mixture of quartz-bearing preparations - as material for embedding and pointing. On this basis of its properties, this composition accorded with the expectations of the monument’s surroundings. Similarly to those executing the original, we worked mostly with packed limestone. Certain colours, e.g. yellow and light green, we made by mixing stones of several hues. For the laying out of the mosaic copy, we fashioned the stone into pieces of appropriate size: first, using power tools, we cut it into blocks and then broke in into cubes approximately 1 cm3 (plus or minus 0.5 cm) using the traditional method, a steel wedge and a hammer.

The copy that was made has been in Room 20 in the main building on the villa farm since June 2012. The copy is to be found in the place occupied by the original mosaic when it was unearthed. In the creation of the copy, conservators and artists took part.

Translated by Chris Sullivan

Márta Guttmann

The Analysis of Organic Materials in Painted Surfaces Using Gas Chromatography Coupled with Mass Spectrometry (GC-MS)

The identification of organic materials is always an important issue in the analysis of paint layers, since by their kind and their condition organic components determine most proprieties of the layers. They are also the ones defining the different painting techniques.

Chemically, the natural organic materials encountered in paint layers each belong to one of the following classes: lipids (drying oils, waxes, ox gall, cholesterol), sugars (starch, gum arabic, fruit-tree gums), proteins (gelatin and glues, casein, egg white and yolk, garlic), resins (colophony, dammar, mastic, etc.), or bituminous materials (asphalt, tar, pitch). They are complex organic mixtures, of variable composition, mainly consisting of macromolecular substances or natural polymers. Identification of organic components is difficult because they undergo chemical changes with ageing, because they are present in the layer together with inorganic materials (pigments, grounds, fillers) that interfere with processes aimed at identifying them, and because samples available for analysis are fairly small (a few pg-s), where the organic material represents at 10% at the very most.

Analytical techniques range from simple histochemical or microchemical methods to more advanced ones like immunofluorescence microscopy (IMF), enzyme-linked immunosorbent assays (ELISA), Fourier transform infrared spectroscopy (FT1R) and related techniques (p-FTlR, ATR), Raman spectroscopy, nuclear magnetic resonance (NMR), mass spectrometry (MS), and gas chromatography coupled with MS (GC-MS).

GC-MS is considered one of the most suitable methods for analysis of organic materials in paint layers, and also enables quantitative measurements. Samples need a chemical pre-treatment whereby proteins, sugars, and lipid-resinous materials are separated, broken down by hydrolysis into small molecules (amino acids, monosacharides, uronic acids or fatty acids, and characteristic fractions of resins, respectively), purified, and derivatised before GC-MS. The article presents an analytical procedure which allows the characterisation of the organic content of a paint layer starting from a unique microsample.

The procedure was applied to three groups of Transylvanian painted heritage items.

The analyses of 38 Transylvanian glass icons dating from the 19th century showed that a wide range of materials were used by the painters of the artefacts, who mostly used for their colours mixtures of a proteinaceous material and a lipid one. Data also highlighted that although the materials employed on all the glass icons under study were similar, some particularities could be observed in the painting techniques of the centres and icon painters that produced them.

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