Abstract

The identification of the chemical nature of varnish is essential for art restorers in order to choose a suitable solvent during its removal. Until today, such identification has been performed using chemical analysis after sampling. An innovative technique is presented here, using ultraviolet (UV) fluorescence spectroscopy. The method is nondestructive, workable in situ, and leads to results in real time. It is based on the comparison between the emission spectrum of an unknown varnish with those of fresh, artificially aged, or old reference resins and varnishes, for different monochromatic excitation wavelengths. The resin and the nature of the varnish as spirit, oil, or mixed can thus be identified. Various examples are presented on home-made samples applied on fluorescent backgrounds and on real works of art.

Fluorescence lifetime imaging and spectroscopy as tools for nondestructive analysis of works of art

Daniela Comelli, Cosimo D’Andrea, Gianluca Valentini, Rinaldo Cubeddu, Chiara Colombo, and Lucia Toniolo
Appl. Opt. 43(10) 2175-2183 (2004)

Identification and quantification of vegetable oil adulteration with waste frying oil by laser-induced fluorescence spectroscopy

Shiguo Hao, Lian Zhu, Ronglong Sui, Mengling Zuo, Ningning Luo, Jiulin Shi, Weiwei Zhang, Xingdao He, and Zhongping Chen
OSA Continuum 2(4) 1148-1154 (2019)

Experimental study on merits of virtual cleaning of paintings with aged varnish

Giorgio Trumpy, Damon Conover, Lionel Simonot, Mathieu Thoury, Marcello Picollo, and John K. Delaney
Opt. Express 23(26) 33836-33848 (2015)

Optical coherence tomography and non-linear microscopy for paintings – a study of the complementary capabilities and laser degradation effects

Haida Liang, Meropi Mari, Chi Shing Cheung, Sotiria Kogou, Phillip Johnson, and George Filippidis
Opt. Express 25(16) 19640-19653 (2017)

Nonlinear imaging microscopy techniques as diagnostic tools for art conservation studies

George Filippidis, Emilio J. Gualda, Kristalia Melessanaki, and Costas Fotakis
Opt. Lett. 33(3) 240-242 (2008)