Conservators have various tools and techniques to aid in the examination of works of art. A handy tool that is easy to transport and can capture a lot of information is a UV light. Paintings can also be photographed under UV radiation to capture this information. Natural resin varnishes display greenish florescence when viewed under UV radiation. Retouching has a tendency to appear black (or non-florescent) next to natural resin varnishes. The images of Leisser's Ben Franklin are in normal illumination (left) and under UV radiation (right).
The during-treatment image shows two things: The area that has already been cleaned of varnish and areas that exhibit overpainted damages - most notably the large damages on the subject's right thigh, right arm, and right hand. The two images beneath show the same UV image with areas of cleaning/overpaint marked in red. The image on the left has a red line marking the area that has already been cleaned. The image on the right has red circles to denote areas of old overpaint.
The images are important because they show that the overpaint exceeds the boundaries of the damage beneath. The previous restorer was heavy handed and attempted to hide the damage under a heavy layer of overpaint. The next blog post in the series uncovers what is under those overpainted areas.