Non-Invasive Assessment of PVA-Borax Hydrogel Effectiveness in Removing Metal Corrosion Products on Stones by Portable NMR

The cleaning of buildings, statues, and artworks composed of stone materials from metal corrosion is an important topic in the cultural heritage field. In this work the cleaning effectiveness of a PVA-PEO-borax hydrogel in removing metal corrosion products from different porosity stones has been assessed by using a multidisciplinary and non-destructive approach based on relaxation times measurement by single-sided portable Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy—Energy Dispersive Spectroscopy (SEM-EDS), and Raman Spectroscopy. To this end, samples of two lithotypes, Travertine and Carrara marble, have been soiled by triggering acidic corrosion of some copper coins in contact with the stone surface. Then, a PVA-PEO-borax hydrogel was used to clean the stone surface. NMR data were collected in untreated, soiled with corrosion products, and hydrogel-cleaned samples. Raman spectroscopy was performed on PVA-PEO-borax hydrogel before and after cleaning of metal corrosion. Furthermore, the characterization of the dirty gel was obtained by SEM-EDS. The combination of NMR, SEM-EDS and Raman results suggests that the mechanism behind the hydrogel cleaning action is to trap heavy metal corrosion products, such as Cu2+ between adjacent boron ions cross-linked with PVA. Moreover, the PVA-PEO-borax hydrogel cleaning effectiveness depends on the stone porosity, being better in Carrara marble compared to Travertine.

Two sculptor-geologists and the perception of marble in nineteenth-century Britain: Sir Francis Chantrey and William Brindley

This article focuses on two British sculptors who straddled the worlds of practical geology and sculpture in the nineteenth century, and in particular how their work affected the scientific and popular understanding of marble. Francis Chantrey and William Brindley were both long-term members of the Geological Society of London and contributed practical understanding of stone to the development of the geological discourse on white and coloured decorative marbles. This article looks at Chantrey’s use of fossiliferous British ‘marbles’ and his role in the growing comprehension of Carrara marble as a metamorphosed limestone in the 1830s. The second part of the article deals with William Brindley’s discovery and popularization of coloured marbles from ancient quarries around the world, and the role of these stones in contemporary imperialist discourse.

‘New Carrara’: Lasa marble in the service of artistic ideas and economic interests during the long nineteenth century

This article discusses Lasa marble, a bright, white and weather-resistant stone quarried in South Tyrol, which in the course of the nineteenth century came to be considered equal, and even superior, to Carrara marble. Because of its quality, Lasa marble has been and continues to be exported worldwide. The article considers the ‘new Carrara’ in light of three art-historical topics: its rediscovery against the background of the intertwining of the young disciplines of geology and art history in the nineteenth century; its use and semantic quality in the context of the new buildings along the Ringstrasse in Vienna; and finally, the various projects for the establishment of artists’ colonies at the quarries of Laas, the declared objectives of which were rooted between monastic harmony and tourism-oriented calculation.