As we mentioned in the previous post How to model the risk of damage for canvas paintings?, following research on mechanical damage in the case of canvas paintings was focused on simulations of stresses induced by the climat variations.
Undoubtedly, paintings on canvas are sensitive to climate fluctuations, such as changes in temperature and relative humidity with large amplitudes or the ones rapidly changing over time, which cause cracking. Most of the paintings in museum collections are covered with a developed network of such cracks, which in turn cause a reduction of stresses in the painting layer. As a result, paintings with evolved crack patterns become more resistant to microclimate fluctuations.
“Breton Brother and Sister” William Bouguereau,
The Metropolitan Museum of Art
Corner of the “Breton Brother and Sister” Williama Bouguereau, The Metropolitan Museum of Art
We simulated this mechanism in our computer model of canvas paintings. For this purpose, we introduced corner cracks into the model in the layer of the painting ground (picture in the upper right corner) with a parametrically changing distance between the cracks S and checked what happens to the stresses in the middle of the region. As we can see in the attached graph, the stress decreases with decreasing S (divided by the thickness of the substrate layer t). This means that the denser the crack network is, the more stable the painting layer is! The different colors indicate the results for different calculated relative humidity drops ranging from 80 or 90% to 20 or 30%. These results confirm that cracked canvas paintings are mechanically stable and thus more resistant to climate fluctuations.
We hope that this is another brick building the idea of a sustainable museum!
This research is carried out as part of the GRIEG project (2019/34/H/HS2/00581) financed by the National Science Center from the Norway Grants.