A painting can be thought of as a complex materials and optical system, made up of inorganic mineral pigments fixed into polymerized organic binding agents (oils, proteins, etc.) on wood or canvas. The paint used is usually relatively thin (between 200-1000 mm) and often layered, with each 10-100 mm thin layer composed of pigment combinations chosen to augment or modify each overlying layer. These heterogeneous and hierarchically arranged pigment mixtures create the unique and specific visual aesthetics well described in the history of art.
A work of art is not a static object separated from the environment in which it persists. Physical and chemical changes in the properties of materials, operating at molecular and micro-scales, can affect the visual appearance of an art object. Various environmental conditions and conservation treatment interventions induce or influence reactions. To understand the mechanisms behind these alteration pathways, CuBISM participants are developing experimental and computational tools to characterize the properties of painted surfaces of works of art. The project outcomes will help conservators to determine how treatments will affect works of art, to visualize the original appearance of an art object, and to project its appearance into the future, also enhancing an understanding of the long-term performance and chemical stability of materials.
a) Vincent van Gogh (1853-1890), The Bedroom, 1889. The Art Institute of Chicago. A detail from the door on the left (b) shows the macroscopic manifestation of zinc soaps as small pinhole protrusions scattered over the surface. A cross section sample (c ) taken form the area highlighted in (b) when observed with backscattered electron SEM clearly highlights the globular forms that are typical of zinc soaps formations at the microscale (d), one of which is almost breaking up the surface of the paint as a protrusion (top left). (e) shows a TEM image illustrating the nanoscale organization of crystalline domains of zinc soaps in a model zinc oxide paint created by the Dutch group.
Themes
Two main themes structure the research:
- Materials Modeling – Molecular to Micro-scale Interactions. Develop experimentally validated material models that describe aging processes in painted materials. Learn More
- Computational Imaging of Composite Materials – Micro to Macro-scale Interactions. Develop the imaging methodologies and analysis procedures that enable materials information to be obtained from images of complex, composite objects consisting of multiple layers, such as painted surfaces. Learn More
The common link shared by both themes is the role of “forward” and “inverse” modeling strategies. In general, an artist begins with a set of materials and production methods. The resultant object evolves and ages over time. Forward modeling generates a prediction of the physical and chemical structure of a painted system—here called “virtual paint.” This “virtual paint” picture is compiled from non-invasive macroscopic and wide-field measurements or from taking minimally destructive samples. Inverse modeling calculates the error between the predictions and the observed material properties, updating the measurable features of the virtual paint to bring it into closer conformity with the actual paint. To carry out these modeling efforts, novel imaging methods are used to extract as much information as possible from layered, heterogeneous material systems, in this case, the painted surfaces.
A graphical depiction of the modeling strategies.
Dissemination
A wide variety of PIRE dissemination and outreach activities are carried out, including journal papers and conference presentation to share results with the cultural heritage and scientific communities, lectures to the academic community, workshops for K-12 students, and online magazine for the general public. Learn More