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Konserwacja i dokumentacja kolczug na przykładzie eksponatów z Muzeum Zamkowego w Malborku

100%

Lesiak M.

Ochrona Zabytków

1968

issue 3

64-66

Sur l ’exemple des cottes de maille provenant des collections du Musée du Palais à Malbork l ’on a examiné la méthode de conservation de ce type d’objets. Après le nettoyage préliminaire de la surface des diverses préparations de conservation et des impuretés, l’objet est soumis à la conservation chimique. Cette dernière consiste en une série de bains dans une solution aqueuse de hexametaphosphate de sodium, à partir d’une concentration de 6°/o jusqu’a 15%, si la corrasion est exceptionnellement difficile à éliminer. Certaines parties fortement corrodées doivent être nettoyées mécaniquement. Des réparations sont également nécessaires déjà au cours de la conservation, afin d’éviter une dislocation des maillons. Après avoir complètement enlevé la rouille, la cotte de maille est rincée dans de l ’eau distillée, séchée à l ’aide de lampes infrarouges et enfin rincée dans du xylène chimiquement pur et recouverte de cire microcristallique.

Wytwarzanie dekoracyjno-ochronnych warstewek tlenkowych na dużych obiektach w ekspozycji zewnętrznej : na przykładzie konserwacji części metalowych Kolumny Zygmunta w Warszawie

51%

Socha J., Safarzyński S., Lesiak M.

Ochrona Zabytków

1979

issue 3

208-220

The Column o f Sigismund III Vasa, the first secular monument not only in Warsaw but in Poland, (1644), to be put up in an open-air setting, was partially damaged during the 2nd world war. In the years 1948—49, during the reconstruction o f the monument, a number o f its cleaned parts and all metal elements were covered with a decorative coating o f a sulphide type. During the last conservation o f the column in 1977 corrosion was removed from metal parts and on their surface a decorative and protective coating o f coloured oxides was produced by means o f a newly developed method. In natural conditions, in the atmosphere free from industrial gases, products o f coal combustion and pollution with substances produced by I.C. engines, a thin coloured layer, mostly made o f cupric oxide (CuO) with a possible admixture o f cupreous oxide (Cu20 ) is usually formed on bronze works. The layer, formed in a natural way as a product o f the reaction o f copper and its alloys with a surrounding atmosphere, is a coating o f decorative and protective nature. That is to say that apart from a decorative effect it markedly improves anticorrosive properties o f the surfaces o f the structures. Oxide layers on copper and its alloys can also be produced in an artificial way, chemically, in the solution o f alkalis and oxidizing agents. In general, conversional oxide coatings on copper and its alloys are produced chemically in the solution o f sodium hydroxide (NaOH) and some potassium persulphate (K2S20 8) added as an oxidizing agent. The formation o f an oxide coating on copper and its alloys in this solution takes place in two stages : — in the first stage (copper dissolution) a compound if formed which is a salt and in which the role o f acid oxide is payed by cupric oxide : S2O2-/8 + 2OH- = 2SO2-/4 + H2O + O Cu + 2OH- + O = СuO2-/2 + Н2O — in the second stage (formation o f the coating) this compound decomposes and isolates cupric oxide which crystallizes on the surface o f the object: CuO2-/2 + H2O = CuO + 2OH- The speed o f dissolving metal in the discussed solution is the highest at an initial period o f oxidation, then it gets down and after a short time acquires a constant value. The authors examined the possibility o f producing oxide coatings on large bronze constructions (monuments), displayed in open-air, through wetting their surfaces with alkaline solutions and oxidizing agents. The results obtained with these trials can be presented in the following way : The solution o f sodium hydroxide and potassium persulphate is really effective only when surfaces are damped with a hot solution. As a result o f this treatment a homogenous coating o f light brown colour and a tint o f putrid green is formed on the surface o f the object (monument). The coating, with products o f copper Dissolving included into it, formed during the creation o f an oxide layer, is bound very well with a metal o f the foundation ; still, it has no decorative expression (it does not make ,,pure” colour). An additional treatment o f brushing with a soft brush damped in a special solution for copper colouring made it possible to extract green products from the layer and give it thus a decorative look. The colour o f the coating obtained in this way may be changed depending on the number o f cycles used, varying from light to dark brown and a tint o f black. Before commencing proper conservation o f metal parts o f the Column of Sigismund III Vasa in Warszawa, the authors made a number o f chemical analyses with both metals o f the foundations o f individual parts o f the monument and o f products o f corrosion. A number o f metalographic microsections o f the superficial layer were made. Apart from deposit corrosion in a form o f relatively loose coatings, mainly o f alkaline copper sulphate, the examinations revealed also more dangerous sub-deposit corrosion (under the surface o f a conversional layer). Analyses made showed a different degree o f the corroding o f individual parts o f the monument and this resulted in a necessity o f a selective priming o f the work’s surface for conservation operations. To begin with, special pastes were used to dissolve products o f corrosion. Then, after a thorough mechanic cleaning, the surfaces were degreased carefully, activated with a mineral acid and an oxide coating was then produced in a way described herein. In the final stage all bronze elements were covered with microcrystallic wax. The oxide layer obtained in this way on the surface o f the monument is a decorative-protective coating, much more mechanically and chemically resistant than traditional sulphate coatings.

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2 Ochrona Zabytków

1 1979

1 1968

2 Lesiak M.

1 Safarzyński S.

1 Socha J.

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Konserwacja i dokumentacja kolczug na przykładzie eksponatów z Muzeum Zamkowego w Malborku

Wytwarzanie dekoracyjno-ochronnych warstewek tlenkowych na dużych obiektach w ekspozycji zewnętrznej : na przykładzie konserwacji części metalowych Kolumny Zygmunta w Warszawie