MOXY project: preliminary investigation of a non-contact cleaning of some typical art materials using atomic oxygen

MOXY project: preliminary investigation of a non-contact cleaning of some typical art materials using atomic oxygen 

Silvia Pizzimenti⁽¹⁾, Tomas Markevicius⁽²⁾, Alessia Andreotti⁽¹), Anton Nikiforov⁽²⁾, Nina Olsson⁽³⁾, Agnieszka Suliga⁽⁴⁾, Gianluca Pastorelli⁽⁵⁾, Nan Yang⁽⁶⁾, Geert Van der Snickt⁽⁶⁾, Ilaria Bonaduce⁽¹⁾  

(1) University of Pisa, (2) Ghent University, (3) ICOMOS Lithuania, (4) European Space Agency ESA, (5) National Gallery of Denmark, (6) University of Antwerp 

Today, contact-based “wet” and “dry” cleaning methods using organic solvents/water/gels are broadly used. However, contact approaches can be limited when treating fragile and porous materials or sensitive artworks, and non-contact cleaning technologies are highly desirable. The ongoing EU-funded MOXY project [1] has embarked on a mission to develop a non-contact cleaning methodology, based on atomic oxygen (AO), generated by non-thermal plasma at ambient pressure to remove carbon-based contaminants in a non-contact way.

In this study, 39 mock-ups were produced using various materials commonly found in cultural heritage, such as plaster, limestone, canvas, paper, acrylic and oil paint, and pastel. These mock-ups were exposed to AO using the low Earth orbit oxygen environment simulator LEOX at the European Space Agency. The samples were intentionally soiled with problematic contaminants such as soot, spray paint, ballpoint pens, markers, and lipstick. During the LEOX experiment, half of each sample was masked with aluminum foil and exposed to the AO flux for varying lengths.  

Samples were examined visually and by spectro-colorimetry at first.  In many cases, the color differences between the pristine and AO-treated areas were around and below the perceivable threshold, indicating that AO efficiently cleaned the substrate surface [2,3]. Investigation with other analytical methods is currently taking place. It includes optical microscopy (OM), 3D Hirox scanning microscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), confocal laser microscopy (CLM), gloss measurements, and analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS).  Directed to the mock-up’s surface, AO removes carbon-based contaminants by converting them mainly into CO, CO2, and H2O vapors [4]. To evaluate the efficiency in removing contaminants, it is possible to rely on some approaches also employed for contact-based methods. However, a new methodology is needed for the AO approach.  In contact and solvent/gel-based methods, evaluating the presence of residues on the artwork surface or the degree of diffusion of solvents used for cleaning is often necessary. Differently from the contact methods, this is not necessary for the AO-cleaning, but the possible effects of atomic oxygen on the artwork itself need to be investigated in depth. This calls for tailored mock-ups and new testing approaches and protocols for cleaning assessment to be combined with traditional assessment methods. The poster presents the preliminary results obtained and discusses the new challenges faced.  

[1] Green Atmospheric Plasma Generated Monoatomic OXYgen Technology for Restoration of the Works of Art  –Art – MOXY - 2022-2026. Grant agreement ID: 101061336. https://cordis.europa.eu/project/id/101061336. 

[2] Sharma, G., Bala, R. 2003. Color fundamentals for Digital Imaging. In Digital Color Imaging Handbook (1st ed.). CRC Press: 31. 

[3] Miller, N.J. Druzik, J.R. 2012. Demonstration Assessment of Light-Emitting Diode (LED) Retrofit Lamps at an Exhibit of 19th Century Photography at the Getty Museum (No. PNNL-21225). In Technical Report, Pacific Northwest National Lab.(Lab. (PNNL), Richland, WA (United States).  

[4] Banks, B., Rutledge, S., Karla, M., Norris, M., Real, W., Haytas, C. 1999. Use of an Atmospheric Atomic Oxygen Beam for Restoration of Defaced Paintings, in Proceedings of the 12th Triennial ICOM-CC Meeting, 1999, NASA/TM-1999-20941.