Varnishes with biocidal activity: A new approach to protecting artworks

Abstract

Keeping agents that cause biodeterioration under control is a common task in restoringand conserving artworks. However, there are very few studies, specifically those concentrating onpictorial works, that provide solutions compatible with the complex mix of organic and inorganicmaterials to be found in such cultural assets. This study aims to use biocide products that arecommonly used in this field (benzalkonium chloride, o-phenylphenol, and tributyltin naphthenate)and which are associated with natural varnishes with a long tradition in artistic practices, in order toprotect paintings and polychrome sculptures from environmental fungi and bacteria without alteringthe original materials or the visual appearance of the artworks. The effectiveness or innocuousness ofthe treatments was tested chemically and visually via optical microscopy, gas chromatography–massspectrometry (GC-MS), and a multidimensional scaling analysis (MDS); the treatments producedgood results as regards the inhibition of microbial growth and scarce interaction with the artisticmaterials being studied.