Multisensorial Assessment of Laser Effects on Shellac Applied on Wall Paintings

The assessment of five different laser treatments in the conservation of wall paintings was devised on the basis of the surface temperature monitoring by infrared thermography (IRT), ultraviolet-induced fluorescence-visible (UV-VIS) imaging, and optical coherence tomography (OCT). A series of yttrium-aluminum-garnet (YAG) lasers were tested for removal of shellac layers from wall painting mock-ups. The mock-ups were realized as buon fresco with different mineral based pigments (earths and iron oxide) on a lime- and sand-based mortar. After the carbonatation process, all the samples were treated with shellac (5% in ethanol). The effects of neodymium (Nd):YAG, holmium (Ho):YAG, and erbium (Er):YAG laser sources, in different operative modes, on average temperature of the surface, color, and morphology were inspected with complementary sensors. The results show the necessity to adopt a combined approach in establishing safe laser operating conditions to avoid any undesired effects induced on the artefacts by the laser treatments. We demonstrate, for the first time, the performance of the Ho:YAG laser in the removal of a conservation treatment.

[1]  Francis Henry Taylor,et al.  The National Gallery of Art , 1941 .

[2]  Caroline Babington,et al.  The Conservation of Wall Paintings , 1993 .

[3]  Frederick E. Petry,et al.  Principles and Applications , 1997 .

[4]  Demetrios Anglos,et al.  Excimer laser restoration of painted artworks: procedures, mechanisms and effects , 1998 .

[5]  G. Petite,et al.  Experimental investigations of laser ablation efficiency of pure metals with femto, pico and nanosecond pulses , 1999 .

[6]  S. Siano,et al.  The Gate of Paradise: physical optimization of the laser cleaning approach , 2001 .

[7]  Roberto Pini,et al.  Achievement of optimum laser cleaning in the restoration of artworks: expected improvements by on-line optical diagnostics , 2001 .

[8]  M. Petró‐Turza,et al.  The International Organization for Standardization. , 2003 .

[9]  D. C. Emmony,et al.  Studies towards a thorough understanding of the laser-induced discoloration mechanisms of medieval pigments , 2003 .

[10]  Philippe Bromblet,et al.  Diversity of the cleaning procedures including laser for the restoration of carved portals in France over the last 10 years , 2003 .

[11]  T. King,et al.  Thermal effects of the Er:YAG laser on a simulated dental pulp: a quantitative evaluation of the effects of a water spray. , 2004, Journal of dentistry.

[12]  Costas Fotakis,et al.  Lasers in the Preservation of Cultural Heritage , 2006 .

[13]  Paraskevi Pouli,et al.  Multianalytical Study of Laser Pulse Duration Effects in the IR Laser Cleaning of Wall Paintings from the Monumental Cemetery of Pisa , 2006 .

[14]  M. Colombini,et al.  Preliminary Results of the Er:YAG Laser Cleaning of Mural Paintings , 2007 .

[15]  P. Pouli,et al.  The potential of UV femtosecond laser ablation for varnish removal in the restoration of painted works of art , 2008 .

[16]  Q. Liu,et al.  Experimental study of temperature and clamping force during Nd:YAG laser butt welding , 2009 .

[17]  M. Colombini,et al.  Free-running Er: YAG laser cleaning of mural painting specimens treated with linseed oil, “beverone” and Paraloid B72 , 2010 .

[18]  Paraskevi Pouli,et al.  A spectral imaging methodology for determining on-line the optimum cleaning level of stonework , 2010 .

[19]  M. Oujja,et al.  Analytical Spectroscopic Investigation of Wavelength and Pulse Duration Effects on Laser-Induced Changes of Egg-Yolk-Based Tempera Paints , 2010, Applied spectroscopy.

[20]  J. Striová,et al.  Chemical, morphological and chromatic behavior of mural paintings under Er:YAG laser irradiation , 2011 .

[21]  Andrea A. Mencaglia,et al.  Laser cleaning in conservation of stone, metal, and painted artifacts: state of the art and new insights on the use of the Nd:YAG lasers , 2011, Applied Physics A.

[22]  M. Oujja,et al.  Wavelength and pulse duration effects on laser induced changes on raw pigments used in paintings. , 2013, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[23]  Ilaria Barbetti,et al.  ULTRA CLOSE-RANGE PHOTOGRAMMETRY TO ASSESS THE ROUGHNESS OF THE WALL PAINTING SURFACES AFTER CLEANING TREATMENTS , 2014 .

[24]  M. Colombini,et al.  Laser cleaning of works of art: evaluation of the thermal stress induced by Er:YAG laser , 2014 .

[25]  M. Colombini,et al.  Optical and spectroscopic tools for evaluating Er:YAG laser removal of shellac varnish , 2015 .

[26]  M. Barucci,et al.  Application of non-invasive optical monitoring methodologies to follow and record painting cleaning processes , 2015 .

[27]  Cristiano Riminesi,et al.  Optical devices provide unprecedented insights into the laser cleaning of calcium oxalate layers , 2016 .

[28]  I. Osticioli,et al.  Temperature-controlled portable Raman spectroscopy of photothermally sensitive pigments , 2017 .

[29]  P. Vandenabeele,et al.  On the stability of mediaeval inorganic pigments: a literature review of the effect of climate, material selection, biological activity, analysis and conservation treatments , 2017, Heritage Science.

[30]  Raffaella Fontana,et al.  Spectral Imaging and Archival Data in Analysing Madonna of the Rabbit Paintings by Manet and Titian. , 2018, Angewandte Chemie.

[31]  B. Becker,et al.  Ho:YAG Laser Lithotripsy , 2019, Ureteroscopy.

[32]  A. Das,et al.  Holmium laser enucleation of the prostate (HoLEP): a review and update. , 2019, The Canadian journal of urology.

[33]  Bruce Gao,et al.  A scoping review of the clinical efficacy and safety of the novel thulium fiber laser: The rising star of laser lithotripsy. , 2020, Canadian Urological Association journal = Journal de l'Association des urologues du Canada.

[34]  Miriam Truffa Giachet,et al.  Characterization and Identification of Varnishes on Copper Alloys by Means of UV Imaging and FTIR , 2021 .