Biocleaning of graffiti

Removal of graffiti is usually performed with mechanical and/or chemical methods. Recently, alternative methods such as laser cleaning and biocleaning have been proposed.
In this research we aimed to formulate new and eco-sustainable methods. In particular, two types of biocleaning tests were carried out: 1) enzymatic cleaning with lipase; 2) fungi based cleaning. The first method was applied on styrene-acrylic pen markers considering that lipase should be able to hydrolyse the ester bonds of acrylic polymers. Aqueous systems and oil in water microemulsions containing different lipases were used: i) a mix of lipases from bacteria (CTS, Altavilla Vicentina, Italy), ii) lipase from Candida rugosa and iii) lipase from Candida antarctica. The o/w microemulsion seemed very promising and its efficiency was significantly improved when lipases were added. The CTS commercial product resulted to be effective as well, but mostly for unaged samples. Moreover, as may be expected, it came out that the effectiveness of the biocleaning methods seems to depend on the chemical composition of the paint material to be removed.
The biocleaning method based on fungi was used for the removal of alkyd-resin spray paints. In particular, tests were performed with white-rot fungi (Phanerochaete crysosporium) known to be able to degrade complex chemical structures such as lignin. Different culture media were tested and encouraging results were obtained.
The effectiveness of the cleaning tests was evaluated by comparing the visible reflectance spectra and by calculating the colour differences of the test specimens before and after cleaning. Moreover, an open source software, IMAGE J, was used to determine the percentage of white in photographs of the treated areas taken in standard conditions. This method was proposed for the first time as a new technique for the evaluation of cleaning tests.

Biocleaning tests on kaolin-pen marker specimens

Published papers
• Germinario G., van der Werf I.D., Montes-Estellés R.M., Regidor-Ros J.L., Sabbatini L., Biocleaning of acrylic materials, Emerge2014, Valencia (Spain), (22-24 September 2014) (extended abstract )
• Germinario G., van der Werf I.D., Palazzo G., Regidor J.L., Montes Estelles R.M., Sabbatini L., Biocleaning of pen markers paints: the role of lipase, in preparation
• Germinario G., van der Werf I.D., Sabbatini L., Regidor J.L., Montes Estelles R.M., Fungi for the cleaning of graffiti : a preliminary investigation, in preparation

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