On 29.09.2010 Maiu Varner defended her master’s thesis “The role of coatings in maintaining stability of panel paintings” at UT Institute of Chemistry.
     Panel paintings made on wood (e.g. icons) are very common in European Churches, especially in the eastern part of Europe. Icons made as panel paintings are very sensitive to humidity fluctuations in the rooms where they are kept. The worst possible conditions are ones frequently found in rural churces: most of the time the rooms are cold and damp but occasionally the roomas are heated for ceremonies. This leads to deformations and cracking of the panels and eventually ruins the paintings.
     It is known that at least part of the problem originates from the highly unbalanced coating of the panels: the front is covered with multilayered gesso and the actual painting, while the back is usually uncoated. The front coating prevents exchange of humidity with the atmosphere while the backside is open for the atmosphere. This leads to formation of asymmetric humidity distribution in the panel, which is largely responsible for the deformations and eventual cracking. An obvious solution to this problem would be finging a suitable protective coating material for the backside of the panels.
     Maiu Varner carried out an extensive one year long climatic experiment on model panels (with 12 different coatings on the back side) in a climatic chamber and monitored changes in the mass of the panels, their dielectric constant and electric conductivity as well as visual appearance. Based on these data she developed a unified parameter characterizing the protective ability of coatings. Using this parameter the different coating materials were ranked by their protective ability. The best protective performance was demonstrated by propolis (followed by a dedicated urethan-alkyd coating).
     These results are expected to be of high value to anyone who is involved in maintenance or conservation of panel painting artifacts. Full text of the thesis is available here (in Estonian).