Biodeterioration on oxidic glasses: part I -- Glaspest on antique glasses as a special kind of biodeterioration on oxidic glasses

摘要

A special kind of antique glasses called Mecklenburger Waldglaeser is often dramatically destroyed. These glasses, produced in the early period of Baroque, show corrosion phenomena like biocrusts and biopits. All biocrusts consist of a specialkind of corrosion layer, a golden coloured layer system called Glaspest. In a historical view Glaspest was a "sickness of glass". Today it is known, that micro-organisms are responsible for this phenomenon. Glaspest is a consequence of biodeterioration,the microbially influenced corrosion of inorganic materials. Glaspest is the corrosion residue of the motherglass, Glaspest is a porous material with the chemical composition [(SiO{sub}2){sub}10CaO(Al{sub}2O{sub}3){sub}2(MgO){sub}0.25(Na{sub}2CO{sub}3){sub}2(K{sub}2CO{sub}3){sub}0.7(Fe){sub}1.3(Cl){sub}0.2Mn]. Glaspest layers are poor of alkaline oxides and especially of calcium. However they are enriched in manganese, iron and aluminium. Glaspest layers have a thickness of 200 nm and form layer systems with a thickness up to 500μm. The nanostructure of these layers is usually in the form of platelet like particles with a diameter of 24 nm. Biominerals like whedellite, calcite as well as alpha quartz, a consequence ofthe glass attack, are found within the layer. The appearance of Glaspest is caused by fungi attack at the glass surface, it is shown by laboratory experiments and in-vitro studies [1].