Envejecimiento natural y artificial para evaluar los tratamientos para impermeabilización del mármol

Exposure of samples to artificial ageing is commonly carried out to test the durability of natural and artificial stones and the effectiveness of products used for their conservation. Correlations between artificial and natural ageing, however, are not always well understood mainly because the former can only try to simulate, in a faster but simplified way, the effects of the many causes interacting ín natural environments. In the present study, marble samples from Carrara and Proconnesion quarries, were treated with four waterproofing products (or mixtures of products) and exposed to artificial ageing while an analogous set was exposed outdoor, in the town center of Rome for two years. Several physical parameters were measured before and after the ageing and the experimental results enabled us to compare the effects produced by the different types of ageing and to estimate the correlations between them. As for the durability of the tested waterproofing products, the two systems are in good agreement even if two years of natural ageing resulted to be slightly more severe than 33 days of exposure to saline fog, to UV radiation and to wetting-drying cyclesLa exposición de muestras a envejecimiento artificial se lleva a cabo comúnmente para chequear la duración de las piedras naturales y artificiales y la eficacia de los productos usados para su cuidado. Las correlaciones entre el envejecimiento artificial y natural, sin embargo, no siempre se entienden bien principalmente porque el envejecimiento trata de simular, de una manera rápida pero sencilla, los efectos de las muchas causas que actúan en el ambiente natural. En este estudio, muestras de mármol de las canteras de Carrara y Proconnesio, han sido tratadas con cuatro productos o mezclas de productos, para su impermeabilización y expuestos a envejecimiento artificial. Mientras, un juego análogo de piedras se exponía al exterior en el centro de la ciudad de Roma, por un período de dos años. Se midieron diferentes parámetros físicos antes y después del envejecimiento y los resultados de la experiencia han permitido comparar los efectos producidos por los diferentes tipos de envejecimiento y de establecer las correlaciones entre ellos. Para la evaluación de los productos de impermeabilización, los dos sistemas son muy parecidos, aunque dos años de envejecimiento natural han resultado ser algo más duros que 33 días de exposición a niebla salina, radiaciones UV y ciclos de humedad-sequedad

XPS characterization of (copper-based) coloured stains formed on limestone surfaces of outdoor Roman monuments

Limestone basements holding bronzes or other copper alloys artefacts such as sculptures, decorations and dedicatory inscriptions are frequently met both in modern and ancient monuments. In outdoor conditions, such a combination implies the corrosion products of the copper based alloy, directly exposed to rainwater, will be drained off and migrate through the porous surfaces, forming stains of different colours and intensities, finally causing the limestone structures to deteriorate

CD-ROM sobre la conservación de los monumentos del Valle del Nilo

The article presents documentary material, discovered at ICCROM Archives, on the conservation works carried out by ICCROM in some monuments of the Nile Valley

A new method to remove copper corrosion stains from stone surfaces

This paper reports on a methodological study carried out in order to propose a cleaning procedure to remove stains produced by bronze corrosion products on surface of limestone (namely travertine); the procedure is effective and more environmentally friendly than the methods commonly used today. Several copper complexing or chelating agents were considered, including three amino acids and compared with some ion exchange resins. After a first laboratory phase on pure copper products and on artificially stained quarry samples, the optimized procedure was tested on the pedestal of a bronze statue in the Sapienza campus, in Rome. Colorimetry and ICP/OES were used to evaluate the efficiency of the cleaning procedure. © 2011 Elsevier Ltd