The Canadian Light Source at the University of Saskatchewan is helping the Art Gallery of Ontario preserve paintings from the mid-20th century. Paintings of that era have a common problem of degradation. The Mid IR Chemical Mapping System at the CLS is being used to help understand why. A conservator at the Art Gallery noticed several of Rita Letendre’s paintings from the 50’s and 60’s had developed issues. Some of the degradation appears as uneven gloss and patchiness, snowy crystalline structures coating the surface, and cracking and lifting of the paint in several areas. The CLS is being used to help understand what in the paint is causing the deterioration. Armed with that knowledge, Senior Conservation Scientist Kate Helwig says, they can choose the right methods of restoration and best practices for long-term preservation.