Kovács Petronella (szerk.): Isis - Erdélyi magyar restaurátor füzetek 18. (Székelyudvarhely, 2018)
Mester Éva: Az ólmozott üvegablakok és üvegfestmények rekonstrukciójának kockázatai
Abstracts Zsuzsanna Tóth Restoration of the Closing Stone During the renovation of Szigligeti Theatre Oradea (Nagyvárad), a metal cylinder was found, which had been placed, as a symbol of closing the construction of the theatre, at the landing of the footsteps in the lobby on October 15, 1990. The Closing Stone, as it was dubbed in contemporary reports, had been walled up, under ceremonial conditions, in a recess closed down by a marble slab at the inauguration of the theater. As the marble slab had disappeared, it seemed improbable to come across the Closing Stone, so it was a big surprise when they finally found it. The metal cylinder contained the minutes of the ceremonial general meeting held on the occasion of the inauguration of the theater, lists with names of the intellectual and material creators of the theater, placement certificate of the Closing Stone, five paper charters and a parchment one. In the recess, all of them had been damaged by humidity and mould, causing corrosion on the metal cylinder, fragility of paper and fading of writing on the paper sheets, as well as crumbling of the coating layer on the parchment charter. Cleaning of the mould-infected documents had to be done in a bioprotective cabin, under air curtain protection. Strengthening of the weakened documents was carried out in several steps, using a 3% alcoholic solution of Regnal, because on a larger surface, the paper impregnated with the solution would have moldered even from its own weight, prior to the settling of the fixative. Documents were disinfected with Preventol, in one session with strengthening. Sheets were filled in following wet cleaning, by leafcasting. The rigid and deformed parchment got smooth above cold water vapor in a couple of hours. In case of the parchment charter, the greatest problem was caused by the cmmbling of its coating layer, and due to this, the loss of text on it. It was an important consideration that fixing the surface should not turn the white coating layer into glaze, and that it should not change the appearance of the parchment. Based on experiments, spraying with dilute fish-glue proved to be an appropriate solution, but it had to be preceded by spraying with alcohol, in order to reduce surface tension. As regards the conservation of the metal cylinder, only the mechanical removal of loose corrosion products and passivation of the surface were carried out, together with a temporary fixing of the moved lead plate of the lid by Artiwood epoxy resin, which can easily be splintered from the surface when needed. Following restoration, the original documents are kept in museum, while their copies, placed in the metal cylinder, got back to the landing of the footsteps in the theatre, together with a similar but smaller metal cylinder containing the document of re-inauguration. Zsuzsanna Tóth Objects conservator artist MA Paper and book conservator Translated by: Katalin Noémi Zimányi Zsuzsanna Várhegyi - Márta Kissné Bendefy Drying of waterlogged archaeological leather finds Although it is widely agreed that for drying of wet organic materials the vacuum freeze-drying is the best method, it is not used for archaeological leather finds in Hungary because of its high expenses. Searching for a more costefficient method authors have found the excellent articles of the conservators of the English Heritage and the Museum of London very promising (Karsten et al 2010, Karsten - Graham 2011). In the experiments of the EH and the Museum of London a new method was used among others as well. The drying of leather finds previously conserved with 20% glycerol solution was carried out at about -26 °C in a domestic freezer where drying was helped not with vacuum but with silica gel instead. The method is mentioned as ’non vacuum freeze drying’, but unfortunately doubts can arise whether the process is a real lyophilisation. The 20% glycerol solution begins to freeze around -5 °C, when only part of the water freezes, making the solution more concentrated. The ‘eutectic temperature’ of the mixture where water and glycerol get both solid is -46.5 °C. Because of that, during freeze-drying the temperature shouldn’t be higher than this temperature, to assure the sublimation. Based on the above phenomenon the drying of the glycerol treated leathers at -26 °C is rather a slow evaporation than sublimation. Nevertheless, in the referred publications it is reported that the leathers were flexible after the treatment and their fibre structure was less closed than the pieces dried with other methods; so it seemed to be a good alternative to substitute the expensive vacuum freeze-drying. Authors Várhegyi and Kissne Bendefy carried out experiments about the water uptake of silica gel, and about drying new and archaeological leather samples to get familiar with the method, and to collect data about the changes during the process. Since all the data available on the water adsorption of silica gel was given at +25 °C, tests had to be carried out to check the process below zero as well. It could be found that while at +25 °C and at RH 60% silica gel adsorbs 32% of its weight, at -25 °C and at RH 60% it can adsorb only about 3%, so the process 132
