2020 Essays

Varnishes in the Rain

Rosenkranz, Naomi; Uchacz, Tianna Helena

In the entry “Varnish resistant to water” on fol. 31r of BnF Ms. Fr. 640, the author-practitioner describes what conservators today recognize as two types of varnish: spirit-based and oil-based. Moreover, he claims that the former resist the rain while latter do not. An experiment was designed to test these claims, informed by previous canvas preparation and varnish making experiments in the Making and Knowing lab. A test canvas, painted with oil paints and covered with four varnishes arranged side by side, was exposed to the elements May 30–Oct 18, 2018, and then compared to a control version kept indoors. Preliminary results suggest that the spirit varnishes are indeed better able to withstand rain than their oil-based counterparts; however, an unvarnished strip of the test canvas faired nearly as well as the spirit varnish, suggesting that the “Varnish resistant to water” may not have been intended to cover oil paint but another medium—perhaps distemper. Additional experiments are needed.