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Studio Dei Materiali Costitutivi E Di Restauro Di Un Dipinto Inconsueto: “S.Irene” Di Giuseppe Verrio
No full textChemical characterisation of spray paints by a multi-analytical (Py/GC-MS, FTIR, μ-Raman) approach
No full textThis study outlines the chemical characterisation of a large number of commercial spray paints as
used in street art, graffiti vandalism and for decoration purposes. The analyses were focused on the
identification of the synthetic binding media, pigments and additives such as plasticisers and fillers,
providing a database as well as a methodology which could remarkably help investigations in a
broad panorama of case studies, ranging from forensic science to cultural heritage. A protocol has
been developed based on a multi-technique approach. In particular, Fourier Transform Infrared
(FTIR) spectroscopy, Pyrolysis/Gas Chromatography-Mass Spectrometry (Py/GC-MS) and μ-
Raman spectroscopy were applied and their strength and weakness points as to the identification of
all spray paints components are outlined. Each sample was first examined with FTIR spectroscopy
as a preliminary screening step to obtain indications on the main binder, which could then be
confirmed and detailed using Py/GC-MS. Some pigments and extenders could be efficiently
identified by examination of the FTIR spectra and pyrolysis products. However, for most samples a
μ-Raman spectroscopy investigation was required in addition to the mentioned techniques in order
to achieve the complete chemical characterisation of organic and inorganic pigments, extenders and fillers. Differences and common features among brands/colours are highlighted and discussed
On plate graphite supported sample processing for simultaneous lipid and protein identification by matrix assisted laser desorption ionization mass spectrometry
No full text
Biocleaning of acrylic materials
No full textIn a restoration, conservation and enhancement of Cultural Heritage project, the cleanup phase is one of the earliest and most delicate operations for the removal of dirt, black crusts, consolidating, protective coatings used in past restorations or, finally, of spray paints. The goal of this study has been to verify the effectiveness of an environmentally sustainable biocleaning method using enzymes, such as lipases, for removing acrylic-based materials. The lipases purchased are extracted from fungi such as Candida rugosa (Type VII Sigma-Aldrich) and as Candida Antarctica (Sigma Aldrich), and various bacteria in a mix of lipase (CTS), and then applied on the specimens specifically prepared. The specimens are white ceramic substrates with a thin layer of different spray paints, markers and Paraloid, all based on acrylic. These materials were analyzed by Py-GC/MS, micro-Raman and FTIR spectroscopy in order to know the chemical composition of the formulations. Usually the spray paints and markers compositions are more complex because they consist of a binder, dyes and/or pigments and additives that confer to paint particular physico-chemical properties.
The lipase action should hydrolyze the ester bond of the acrylic copolymers, transforming them from hydrophobic to hydrophilic compounds, facilitating their removal. The enzymes have been applied directly on the test specimens by employing both simple aqueous systems, or direct microemulsions in different conditions of time and temperature. The optimum activity of each lipase considered (pH and substrate concentration) was studied spectrophotometrically on a standard substrate
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