Műtárgyvédelem, 2009 (Magyar Nemzeti Múzeum)
Erőss Dóra: Három kelta bokaperec restaurálásának tanulságai
Erőss Dóra • Három kelta bokaperec restaurálásának tanulságai The examination of the superficial layers was especially important at the conservation of the four (two separate items and a pair) the LaTene period bulbous anklets since it had to be determined if the patinated surfaces were the original ones or the black, cracked layer that covered the anklets recovered from a cremation burial. The X-ray diffraction analysis revealed that the black layer was composed of the transformation products of the components of the bronze alloy produced by burning, so it was not a deposited layer. The same was supported by the fact that during the optical examination of the surface, ornamental motives and tool marks were found on the agglomerated black layer, which could not be seen on the patinated surfaces. Pseu- domorphous textile remains were also found on the surfaces of two of the anklets. The analyses of the structure of the objects revealed the followings. The tin bronze metal core (80-85 % copper, 5-10 % tin and 5-10 % lead) was covered with coloured corrosion products. The exterior surfaces of the object burned and cracked through which moisture penetrated to the metal core and thus a patina developed on it. But this was not the original surface of the object. The original surface of the anklets was the black cracked peeling layer that covered the patina. A carbonate deposition that developed after the objects had been buried covered this layer, which preserved the pseudomorphous textile remains. The only method that could be used from the cleaning and conservation processes was a careful mechanic cleaning. The laminate structure of the objects caused difficulties during conservation since the conserving material could not satisfactorily reach the problematic areas. We chose a method, in which the material reaches the surface in a vapour phase similarly to moisture (ammonium hydroxide — acetonic dechlorination process). However, it did not bring a satisfactory result so we laid a great emphasis on passive stabilisation: an airtight packing was prepared in which the objects can be preserved within dry circumstances. We made our best to choose a cheap and easily obtainable packing, so we placed the objects in a nest prepared from Austrotherm extruded polystyrene heat-insulating material and laid them, together with 250 g conditioned silica gel filled into unbleached, loosely woven cotton bags, into food boxes distributed by the Curver firm. A szerző címe/Authors address: Erőss Dóra Fém-ötvös restaurátor művész/ Metal and goldsmith conservator MA e-mail: dora.eross@gmail.com 1031 Budapest, Saroglya utca 22712. 145
