Mounting & ‘Dis’mounting: Historical Practices and Conservation Issues in Oil Paintings on Paper

Oil painting on paper remains an understudied and scarcely documented technique. Long considered uncommon, it was in fact widely practiced by major European artists from the 15th century onward. Hundreds of artworks stored in museums, print and drawing rooms, private collections, show that painters employed thoughtfully specific ways to combine these two materials, with opposite and incompatible properties, often for works requiring rapid and precise execution: study heads, monochromes, bozzetti, and natural subjects, where the paper may be partially or completely covered by the painting layer. This research, developed within a PhD project in Heritage Science at Sapienza University, focused on oil painting on paper technique between the 15th and 19th centuries, demonstrates that many of the issues concerning identification and conservation are closely connected to mounting and dismounting systems. Historically, oil paintings on paper were frequently mounted onto secondary supports, such as canvas or panel, and then framed. Problems related to the interactions of hygroscopic supports, sensitive to fluctuations in temperature and relative humidity result in movements such as expansion or contraction. In addition, secondary supports affect the aesthetic of oil paintings on paper by concealing the paper layer. Because of paper’s thinness, the texture of canvas could be imprinted on its surface, often making visible the primary support only when damages, such as tears and losses, occurred. In the case of panel mountings, paper was sometimes fully adhered to the wood, where fibers can be recognized through technical examination by conservators. This assembled structure had two consequences: o First, these works were often miscatalogued as oil on canvas or oil on panel, masking their true nature and leading to the loss of essential technical information. o Second, conservation treatments were generally carried out by painting conservators, using tools and methods specific to canvas or panel, with greater attention to the paint layer than to the paper support, which in some cases was even removed. Problems such as ondulations, cracking, and lifting are particularly evident in works mounted on canvas, where strong adhesives and invasive lining methods contributed significantly to the deterioration of the paper supports. In many instances, such canvas mountings represent later phases, replacing earlier systems, often involving panels. Paintings on paper mounted on panels show different features: the surface is often smooth and even, suggesting that adhesion of the paper may have occurred before painting. In this case, paper could serve as a preparatory layer, substituting for gesso grounds. However, this possibility has generally been overlooked, and the structure interpreted as a later intervention, leading to dismounting and remounting treatments. Through the examination of artworks, archival sources, published literature, and, when available, museum conservation reports, this research traces systematic approaches adopted from the mid-19th to the late 20th century. The overview offers an opportunity to reassess these practices and to underline the importance of recognizing and classifying mounting systems. Proper understanding of these structures is essential for correct identification and cataloguing, that are crucial for developing conservation strategies that respect the material integrity of oil paintings on paper.