Kovács Petronella (szerk.): Isis - Erdélyi magyar restaurátor füzetek 7. (Székelyudvarhely, 2008)
Herceg Zsuzsanna: Új anyagok, új eljárások a szilikátalapú műtárgyak restaurálásában
The chronological and spatial distribution of the use of certain pigments is generally known, thus the identification of the pigments provides objective data for dating. The priming of paintings is characteristic of the period and the painter, and the white pigment of the priming (chalk, barite, lead white, zinc white, titan white etc.) can easily be identified. The analysis of the accompanying minerals of lapis lazuli has successfully been applied for the determination of provenance. The identification of the decomposition products of the pigments on discoloured paintings can help the reconstruction of the original colours. E.g. yellow auripigment (As2S3) turns into colourless arsenic trioxide (As203) in effect of light. The analysis of plaster can yield important data on the materials and methods of production and help the choice of the conserving method. The crystallinity of the lime (calcite) of the plaster can tell if it came from the binding of quicklime, lime dust or marble dust. When lime is present in the form of an aragonite modification, it means that ground bivalve shells were used. Beside calcium carbonate, magnesium carbonate (magnesite) also develops from lime produced with the burning of limestone of a high Mg content. This can help the identification of the limestone quarries and calls our attention to the fact that plaster is more sensible to the deteriorating effects of acidic sulphate moisture. The distribution and the crystalline content of the gypsum content tell if it was intentionally mixed in the plaster or it developed from the lime in effect of acidic rainwater (or ground water). Killed plaster mixed into the plaster and locally bound plaster can be differentiated by crystallinity. The X-ray diffraction analysis of ceramics offers information on the raw materials, the firing temperature and technology. The crystalline components of glazes and pigments can also be identified. The analysis of metals and alloys tells about their composition and the method of their production, while that of the corrosion products reveals the causes and circumstances of corrosion and the composition of the original alloy. The analysis of gilded surfaces helps in the determination of the gilding technology. The sizes of the crystallites of gold and the distribution of their direction can be determined with diffraction analysis, and they inform about the production technology (gold foil, fire gilding, galvanization or vapour metalizing). Tin plague and deformations caused by oxidative corrosion can be differentiated on tin objects. The method can also be used for the identification of the materials of other art objects, minerals, jets and precious stones and rocks. The more exact petrologic analysis of rocks can contribute to the identification of provenances, possible mines and the drawing of possible trading routes. The interpretation of the data is the most crucial part of the analysis. The crystalline components of the samples can be identified by comparing the data with a reference database. When the sample contains a material that cannot be found in the database, further analyses can help in the identification of the crystalline component. Special reference measurements can be made of the characteristic material types (e.g. pigments, ceramics, etc.) to help the interpretation of the measurement data. It would be useful to make more analyses to support the conservation work. Regrettably, the majority of the results of analyses are not published in a form that can easily be reached by conservators. The publication and the systematic archiving of the existing data would be very important. István Sajó Hungarian Academy of Sciences -Chemical Research Center H-1025 Budapest, Pusztaszeri út 59-67. Tel: +36-1-438-1100/114 intem E-mail: sajo@chemres.hu István Bóna Conservator on the faţade Reconstruction of the faşades of monuments from a conservator’s aspects The paper tries to determine what conservation means in the case of the reconstmction of facades. The author cites examples to illustrate that historical facades can be preserved in their original materials. He also wishes to show that reconstmction from a conservation aspect not only uncovers the real monument: it can also be economic. He adds that conservation and preservation does not always mean the exhibition of the original surfaces. The so-called sacrificed layers can be applied first of all at the conservation of faşades. This means either that the oldest surface is not uncovered since the later layers protect it, or we coat the original surface with materials that can protect the original one while they themselves decay (e.g. with limy mortar, gypsum plaster or whitewashing). It is an irresponsible act to uncover the original surfaces of renaissance or gothic faşades since we cannot protect them, not even with the latest technologies, against the deteriorating effects of the weather. The author argues that faşades are integrated parts of the buildings and they were not accidentally prepared in the form that we can see. The material, the colour and the facture of the coatings generally have meanings and if we change them, we change the meaning of the building as well. So the investigation and the study of the history of faşades are indispensable in the case of monuments and the designs of the reconstruction must be based on their results. This must determine the methods of treatment as well: will the faşade be conserved or renovated? Several paragraphs question the actually accepted theories and interventions, first of all the use of industrial materials in the process of conservation that were developed for other purposes than conservation. These materials and procedures are appropriate in the right cases but their inappropriate application can deteriorate the monuments. 142
