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Saturday, June 2 • 11:30am - 12:00pm
(Research and Technical Studies) The use of nano-indentation to mechanically characterize embedded artists’ materials

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The Managing Collection Environments initiative at the Getty Conservation Institute focuses on research questions and practical issues relating to the control and management of collection environments in museums. Providing an evidence-base for the effect of environmental conditions on historic materials has long been a challenge for the conservation field, due to both the inherent complexity of the materials and the uncertainty in the mechanisms at play in environmentally-induced change. Understanding the mechanical properties of cultural heritage materials is a fundamental aspect of establishing effective preservation methods. Conventionally, the mechanical characterization of artists’ materials is performed by uniaxial or biaxial tensile testing and typically requires a large quantity of macro-sized samples. Having access to sufficient numbers of historic materials that satisfy this sample size requirement is impractical if not impossible when working with museum collections. As a consequence, the applicability of macro-mechanical testing in the conservation science can be limited. In contrast, small scale engineering techniques such as micro- and nano-indentation allow for the characterization of sub-millimeter samples taken from real works of art, rather than relying wholly upon much larger laboratory-prepared samples intended to mimic historic materials. These engineering techniques open a new perspective on the systematic analysis of the probabilistic distribution of mechanical properties of artists’ materials. They also allow for the analysis of ageing factors which can alter the mechanical properties of a material. The primary focus of this study is the application of micro- and nano-indentation to investigate the effect of an embedding process on the mechanical properties of cross-sectional samples of acrylic-based paint. As a precursor to the analysis of historic samples, a systematic investigation of embedded samples was performed to assess the role of sample size, surface roughness and structural compliance of the embedding resin. Material characterization was conducted at ambient laboratory conditions using an Ultra-High Resolution Nanoindentation Tester (Anton Paar) equipped with a Berkovich (three-sided pyramidal) diamond indenter. Load–displacement tests were carried out on embedded and free-film samples to evaluate the quasi-static and dynamic behavior of the acrylic-based paint to better understand its deformation response. Mechanical parameters which are used for describing the stiffness of a material, such as the elastic behavior of a material (storage modulus) and the ability of the material to deform under constant load (creep), were obtained for cross-sectional samples and compared with results for the acrylic free-film. Results indicate that instrumented indentation can be successfully used as a stepping stone towards an improved understanding of mechanical properties of embedded artists’ materials and, consequently, allow one to better define the conservation needs of art objects.

avatar for Ashley Freeman

Ashley Freeman

Research Lab Associate, Getty Conservation Institute
Ashley Freeman joined the GCI in 2016 to work on the Managing Collections Environments Initiative. She graduated from Queen's University with a M.A.C. in Conservation Science, received a study certificate for restoration and conservation from the Lorenzo de' Medici, MS in Chemistry... Read More →

avatar for Vincent Beltran

Vincent Beltran

Assistant Scientist, Getty Conservation Institute
Vincent Beltran joined GCI Science in 2002. He has been an active participant in a range of research projects including the mechanical characterization of historic materials, the effect of reduced oxygen environments on color change, evaluations of packing case performance during... Read More →
avatar for Michał Lukomski

Michał Lukomski

Scientist, Getty Conservation Institute
Dr. Michał Lukomski is head of Preventive Conservation research, which assesses the effects of environmental conditions and lighting on museum objects. He received his PhD in physics from the Jagiellonian University in Krakow, Poland, in 2003 and completed his postdoctorate fellowship... Read More →

Saturday June 2, 2018 11:30am - 12:00pm MDT
Meyerland Meeting Room Marriott Marquis Houston
  6. Specialty Session, Research and Technical Studies