Scientific Results

Multi-analytical approach to the study of mecca gilding technique

Year: 2021

Authors: Chaban A., Lanterna G., Gigli M.C., Becucci M., Fontana R., Striova J.

Autors Affiliation: National Institute of Optics INO-CNR, 50125 Florence, Italy;
Scientific Laboratory of Opificio delle Pietre Dure, 50129 Florence, Italy;
Department of Polychrome Sculptures, Opificio delle Pietre Dure, 50129 Florence, Italy; Department of Chemistry ‘Ugo Schiff’, University of Florence, 50019 Sesto Fiorentino (FI), Italy

Abstract: Meccatura is a type of historical gilding technique, which consists in the application of a coloured varnish on
burnished metal surfaces (silver or tin foil) with the aim to both imitate the golden surface and to protect the
metal from tarnishing. Since the medieval period in Europe, it has been applied in paintings, carved wood altarpieces, frames, polychrome sculptures, and decorated leather. There is a variety of mecca historical recipes,
which report on different organic substances, e.g. siccative oils, resins (sandarac, colophony, shellac etc.),
organic dyes (saffron, dragon’s blood, gamboge, aloe etc.), plasticizers (beeswax or carnauba), often unknown,
subject to degradation phenomena and past interventions. More recently, the classical mecca antica has been
substituted with mixtures of synthetic colourants charged with pigments and inert materials, the so called mecca
moderna. Due the complexity of present materials, this represents an analytical challenge for heritage scientists
and conservators. With more attention dedicated to the traditional gilding techniques, available scientific results
on the meccatura are rather fragmentary, being part of a larger multi-analytical study on decorated artworks. This
paper focuses on meccatura research issues, outlines the gaps in their scientific study and evaluates several
methodologies to overcome them. In specific, the limitations and contributions of complementary Raman and
Fourier-Transform Infrared (FTIR) Spectroscopies to the study of main traditional mecca components are
analyzed and discussed, supported by structural information from Optical Coherence Tomography (OCT) and
colorimetric measurements by Fiber Optics Reflectance Spectroscopy (FORS). The experimental study is carried
out on mock-ups and on a real case study. The paper highlights potentials, limitations and future perspectives in
the development of non-invasive analytical approach to the investigation of historical and modern mecca varnish
recipes, their alteration and ageing.

Journal/Review: MICROCHEMICAL JOURNAL

Volume: 168      Pages from: 1  to: 9

More Information: The publication contains experimental results on ad-hoc designed mecca mock-ups, prepared according to traditional recipes
KeyWords: Raman spectroscopyPortable Fourier Transform Infrared Spectroscopy; Complementary; Meccatura; Varnish Ageing
DOI: https://doi.org/10.1016/j.microc.2021.106415

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