Saving Hagar: The Exploration of the Degradation Mechanism of a Renaissance Era Oil on Copper Painting.

The Expulsion of Hagar is one of several oil on copper paintings by C.W. Deitrich from the 1700\u27s. Over its uncertain history the painting has been exposed to a variety of conditions. During recent restoration efforts the presence of copper soap, unusual protrusions, and paint flaking was observed. While the formation of green copper oxide layer is also observed on many other copper art pieces and is well studied, our focus is these protrusions that eventually break through and form micro-eruptions on the surface. Our goal is to determine the chemical reaction occurring producing these anomalies. Optical and electron microscopy techniques have been used to image this degradation process as well as non-damaged areas of the painting. The current hypothesis is that the protrusions are forming as a reaction between the copper plate, the organic layer used to prime the painting, and other metals present. So far, the EDS results indicate a presence of copper, oxygen, and carbon in the organic primer, as well as various copper oxides in the protrusions which may be indicative of a galvanic corrosion process. By further researching this degradation process we hope to provide art conservators and historians with a tool to help preserve valuable and historic art as well as provide insight into the degradation of other oil on copper paintings