The Feasibility of Flash Thermography for the Examination and Conservation of Works of Art

摘要

This study investigates the feasibility of flash thermography for the examination and conservation of works of art: paintings, works on paper and sculpture. Thermography is a non-destructive technique for the identification of subsurface defects in materials. It is based on the propagation of surface-deposited heat through into the material. Differences in propagation between defect and defect-free areas result in a difference in the surface temperature of the material. The surface temperature is mapped over time by imaging with a mid-infrared digital camera. A xenon arc lamp is used to provide the initial source of radiation, and signal processing is typically applied to the collected data to reduce noise and to enhance key signal characteristics. This technique offers the possibility of investigating the structure of paintings and paper, particularly in cases where other non-destructive examination techniques do not provide sufficient information, for example subsurface delamination and layer structure. The results indicate that thermography is a good technique for detection of paint delamination and the degree of adhesion between layers, particularly in canvas paintings. It also successfully detected wood grain in situations where X-rays did not, although it was not effective for detecting voids or defects in wood.