Evaluation of Medieval Estonian Murals with a Focus on Painting Technique: Novel Findings on Paint Layer Composition

The current study gives an analytical overview of the medieval(13th–15th century) wall-painting techniques and materials used inEstonia. The research is mainly based on visual observations atspecific locations and on micro stratigraphic sample analysis usingoptical and electron microscopy and energy dispersive spectroscopy(EDS). Additionally, microchemical spot tests were carried out todetermine the presence of organic additives in paint layers. Samplesfrom eleven churches were examined (Ambla, Järva-Peetri, Koeru,Türi, Martna, Ridala, Muhu, Valjala, Pöide, Kaarma, Lüganuse,Haljala). Three paint layer samples, originating from Pöide, Koeruand Ambla churches, were analysed by the gas chromatographymassspectrometry (GC-MS) method to determine the type oforganic binder additives used in the paints. The article presentsthe information gained from the first analytical and comparativematerial study of the wall-paintings preserved in medieval Estonianchurch architecture. Microscopic analysis of the stratigraphy ofplaster and paintings revealed the usual layered structure in theexamined paintings: typically, a preparatory limewash layer wasapplied to the plaster before the mural painting, though in two cases, the painting was executed directly on the plaster. The findingsindicate that dolomitic lime of different quality is the main andmost common binder in both the underlying plasters and lime wash.Aerial calcitic lime was used for the limewash in only two paintings.Building on these insights, an experimental study was conducted toreplicate the original technique, aiming to practically test the wallpainting methods employed during the studied period. The focusis on the interior paintings as well as two examples of the exteriordecoration. The study contributes to local and regional technical arthistory and to conservation specialists’ better preservation decisions.