The surface behavior of gilding layer imitations on polychrome artefacts of cultural heritage

Abstract

This paper proposes the first results of a larger study on the behavior of gilded surfaces of polychrome heritage artefacts with the aim to understanding the surface patterns and roughness variations before and after specific treatments (burnishing and varnishing). This study can be useful to trace correlations between the compositional features, manufacturing and applications/elaboration processes of gilding layers and the pattern of the surface topography, and also some insights into the degradation/corrosion mechanisms. The results obtained on imitations of gilded surfaces can be further useful for recognizing fake surfaces in the authentication of artefacts from the antiquity markets.Two types of commercial imitations of gilded surfaces on a wooden support were considered: liquid 'gold' (Cu-Zn powder in a solvent) and 'gold' leaf (Cu-Zn leaf) applied over bole and gesso layers.A combined analytical approach using atomic force microscopy (AFM), optical microscopy (OM) and colorimetry (CIE L * a * b * system) was applied in order to better understand the behavior of the gilded-varnished surface and of the interface between the metal surface and the other preparative layers.

Colorimetric and microscopic study of the thermal behavior of new ceramic pigments

“…In agreement with (Sandu et al, ; Wyszecki and Stiles ; Sandu et al, ; Buxbaum and Pfaff ; Sandu et al, ) the color difference parameters between the (T) sample and the (R) reference pigment are expressed by the mathematical equations: …”

“…In agreement with (Sandu et al, 2000;Wyszecki and Stiles 2000;Sandu et al, 2001Sandu et al, , 2002Buxbaum and Pfaff 2005;Sandu et al, 2010Sandu et al, , 2011 the color difference parameters between the (T) sample and the (R) reference pigment are expressed by the mathematical equations:…”

Atomic force microscopy as a tool for binder identification in ancient photographic processes

“…Noninvasive analytical tools are mainly requested in the diagnosis and scientific studies of cultural heritage assets and some of the recent applications of AFM showed the potential of this technique in the field of conservation science . Nevertheless, a systematic use of this technique for gilding layer characterization on artefacts of cultural heritage has not yet been reported …”

“…1,2 The typical evaluator of these objects is the art historian or the restorer-conservator who usually does not have access to modern techniques of analyses to check the authenticity of the materials. 3 The behavior of the materials in many situations can also be a source of errors if their study is based only on superficial observation by the naked eye of magnifying glass. 4 Identifying the compounds in the case of photography further complicates this task due to the complexity of materials arranged as strata.…”

“…has not yet been reported. 3 A number of different working methods have been developed and introduced to aid in the identification process of photographs. [9][10][11] Most of these methods are based on just a visual examination and, in some cases, are complemented with a low power microscope.…”