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KSbOSiO 4 microcrystallites as a source of corrosion of blue-green lead-potassium glass beads of the 19th century Presently, deterioration of glass beads is a significant problem in conservation and restoration of beaded exhibits in museums. Glass corrosion affects nearly all kinds of beads but cloudy blue-green ones are more than others subjected to disastrous destruction. However, physical and chemical mechanisms of this phenomenon have not been understood thus far. This article presents results of a study of elemental and phase composition of glass of the blue-green beads of the 19th century obtained from exhibits kept in Russian museums. Using scanning electron microscopy, X-ray microanalysis and X-ray powder analysis we have detected and investigated Sb-rich microinclusions in the glass matrix of these beads and found them to be micro crystallites of KSbSiO 5 . These crystallites were not detected in other kinds of beads which are much less subjected to corrosion than the blue-green ones and deteriorate in a different way. We believe that individual precipitates of KSbSiO 5 and especially their clusters play a major role in the blue-green bead deterioration giving rise to slow internal corrosion of the bead glass.

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The article reviews the main physical and physicochemical factors influencing the three-component system “fingerprint powder – prints bearing surface – sweat and grease print substance”. The authors propose new model compositions of fingerprint powders considering the reviewed common patterns: non-magnetic and luminescent magnetic. The features of prints bearing surfaces and developed fingerprint powders have been evaluated by applying electronic microscopy methods (scanning and probe microscopy). The authors have proven that the use of nano- and ultra disperse materials in the developed compositions (carbon nanotubes and shungite) enables to vary the sorption and adhesive capacity of fingerprint powders, which allows detecting fingerprints on varying surfaces with high selectivity toward the sweat and grease print substance and contrasting effect.

Intact and degraded domains are analysed in the same glass beads using FTIR and SEM • Glass depolymerizes in degraded domains and does not depolymerize in intact ones • Alkali elements migrate from degraded domains to intact ones due to internal stress • Internal stresses drive glass depolymerization, bleaching, cracking and fragmenting • Atomic-level thermal fluctuation mechanism of glass stress corrosion is discussed