Stage 1 (Tomaž above Praprotno)

Corpus » Succursal church of St Thomas

Interactive drawing

Technical analysis

The northern side of the triumphal arch: the oldest layer (?), the red fragment

Pigments: red earth (haematite)

Analytical techniques: OM, Raman, XRD

 

The northern and southern sides of the triumphal arch: kneeling figure, Crucifixion, saint

Pigments: white lime (calcite), yellow earth (goethite), red earth (haematite), green earth

Analytical techniques: OM, Raman, XRD

The northern side of the triumphal arch: the oldest layer (?), the red fragment

The plaster consists of lime and sand, as confirmed by an X-ray diffraction (XRD) analysis. The plaster’s predominant ingredient is calcite, i.e. lime as the binder, while the aggregate is mainly quartz. The plaster also contains a modest amount of dolomite and feldspars. The cross-section of the sample does not indicate any limewash. The plaster is very bright and rich in binder (calcite), while the aggregate consists of fine light granules (Fig. 1). The fragment in question is minuscule and covered with a more recent mural, so we cannot discuss any potential giornate, while its surface is quite uneven.

 

The northern and southern sides of the triumphal arch: kneeling figure, Crucifixion, saint

The plaster is very brittle and falls apart quickly, while the colour layers do not adhere well and keep peeling off. The plaster on the southern side is even more brittle than the one on the northern side; it may have been consolidated more thoroughly on the southern side during the restoration process. In the cross-sections, the plasters on the southern and northern sides of the triumphal arch appear identical, made from lime and sand consisting of varicoloured angular grains of different sizes (Fig. 2). They contain a lot of aggregate and not so much lime, and the lack of binder causes the plaster to crumble. The X-ray diffraction (XRD) chemical analysis confirms the predominance of quartz with only a little calcite and even less dolomite, as well as the presence of a significant amount of impurities (feldspars, illite/muscovite, kaolinite), indicating a poorly washed sand. The plaster on the south wall contains some more dolomite and less quartz as the one on the northern wall, but probably it is the same plaster and work of the the same worksop. In some cross-sections, at least one layer of limewash is discernible. No giornate are distinguishable. The plaster in question differs from the one belonging to the fragment of the oldest layer of murals.

The northern side of the triumphal arch: the oldest layer (?), the red fragment

Red earth was used, which is also evident from the cross-section. As indicated by Raman spectroscopy, the red earth is haematite with traces of kaolinite. It was applied in a thick layer of paint, and lime from the plaster was used as the binder.

 

The northern and southern sides of the triumphal arch: kneeling figure, Crucifixion, saint

The mural is painted in yellow, red, pink, purple, green, and brown. The cross-sections reveal yellow and red earth (Fig. 2), which the Raman spectroscopy identified as goethite and haematite; the latter is also contained in the purple colour. Green earth can also be identified, while there is no evidence of any malachite content. The brown colour is probably umber or perhaps burnt yellow earth. The pink colour of the drapery is a mixture of white lime and just a smidge of red earth (Fig. 3), while the pink carnation contains more red. The binder is mainly lime from the plaster, confirmed as calcite. For the final contours and additions, the pigments may have been impregnated with an organic binder such as egg yolk, animal glue, or casein.

The northern side of the triumphal arch: the oldest layer (?), the red fragment

The mural was painted al fresco, i.e. on fresh plaster. The boundary between the colour layer and the plaster indicates that the lime permeated towards the surface.

 

The northern and southern sides of the triumphal arch: kneeling figure, Crucifixion, saint

The mural was painted on fresh plaster, i.e. al fresco (Fig. 3), combined with the al secco technique for the final modelling and contours.

The northern side of the triumphal arch: the oldest layer (?), the red fragment

We are discussing a tiny fragment of red colour, which does not allow for any elaborations on the painting process involved.

 

The northern and southern sides of the triumphal arch: kneeling figure, Crucifixion, saint

There is no evidence of any incisions, not even on the saints’ halos. The underdrawing is outlined in a darker red colour, as best seen in the case of Christ’s feet in the Crucifixion scene (Fig. 4). In some cross-sections, there is a clear thin red layer under the base colour layer, which may also be an underdrawing (Figs 2–3); samples were taken from the spots where the painter could have outlined the folds of the drapery. There is no underpainting in the true sense of the word: local colour tones are used for the draperies and faces. These were applied using broad brushes, while the painter drew the lines of the vertical parallel or bowl-shaped wrinkles on top of them with a thinner brush. The facial features were outlined with a dark red contour, which the painter also used as the final line for all the figures. He drew slightly semicircular eyebrows, too long for the faces, and outlined large eyes with a semicircular top and a flat bottom edge. The nose proceeds from the inner eyebrow; it is straight, though the tip appears pointed. It has not been preserved in its entirety on any of the figures. The mouths are also severely damaged, but they must have been rather fleshy, as we can still discern in the face of the saint above the Crucifixion scene. The hands are too large for the figures, while the fingers are unevenly thick and separated by a strong final contour. Christ’s naked body is slender, with the ribs and the chest outlined somewhat schematically. The hair was painted using simple wavy strokes on the primary colour base, as can be seen quite clearly in the case of the kneeling figure with yellow hair and dark brown strands. The colour modelling has largely fallen away from both the carnations and draperies. The kneeling figure on the northern wall has also a darker ochre layer shading the area under the chin and the diagonal neck tendon, while the saint on the northern wall features shading of the round chin and the lower edge of the jaw as well as an ochre layer under the eyes and on the nose. On the southern side of the saint’s mantle, the folds were shaped using shadows and highlights.

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Tomaž above Praprotno, Succursal church of St Thomas, Stage 1 (Tomaž above Praprotno), 2024 (last updated 6. 9. 2024). Corpus picturarum muralium medii aevi, https://corpuspicturarum.zrc-sazu.si/en/poslikava/phase-1-tomaz-above-praprotno/ (13. 10. 2025).

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