Historical Painting Techniques, Materials, and Studio Practice

marbled columns, multicolored paintings on the panels, and blue and silver
paintings on the podium. The identities of the artists are unknown (Fig. 2).
Methods
Analysis of the pigments was carried out combining optical microscopy, microchemical
tests, and emission spectroanalysis (2, 3). Media were determined
by the use of thin-layer chromatography, infrared spectroscopy, and microchemical
tests (4, 5, 6) .
Materials and results
Technical analysis from paint samples was executed to reveal the original layer
of the pulpit of the Nurmuizha church. Samples were taken from the background
and profiles of the pulpit's twisted columns (now black) and from the
decorative wood carvings of grapes, masks, and reliefs (now gold) . The results
indicate that the ground layer consists of an unpigmented calcium carbonate
bound with an animal glue, as was shown by staining tests. In the cross section,
the ground layer is shown as a white layer with some small brown glue
particles. On a thin transparent layer in which protein has been fo und, there
is a black layer with occasional particles of a blue pigment. The few blue
particles present are transparent; a positive identification of the pigment was
impossible. Later overpaintings are executed in black, containing charcoal and
oil. The decorative vines are gilded. The underlayer is composed of calcium
carbonate and glue. In the cross section, a layer of brown hematite is visible
and the presence of glue particles was determined with staining tests. On top
of the gilding there is a layer of mordant gilding: oil pigmented with ochre
and minium, the latter probably acting as a drying agent. The bronze layer
on the pigmented oil layer was applied much later.
Figure 3. Cross section if paint sample from
part if the flesh color on a sculpture in the
Nurmuizha church. The layers are as follows:
(1) thin pink ground, (2) main paint layer
containing lead white and ochre, (3) transparent
layer containing oil, (4-8) overpaints.
Photograph by M. B. Vanaga and R. Kanins.
Samples were taken from the clothes, hair, and flesh color of one sculpture
on the pulpit (Fig. 3) . The analyses showed that the gilded wrap was executed
in a water-gilding technique, while the dress itself was originally blue. The
blue layer consists oflead white and smalt with tempera as a binding medium
on a chalk-glue ground layer (7). Analysis of the samples taken suggests that
the pulpit had water-gilded, wood-carving details on a blue background. The
same blue color is also fo und in other details of the church's decoration (the
altar and the decorative ledge). Later overpaintings, however, have penetrated
the original, damaged layer, changing it and making a correct analysis difficult.
During the technical investigation of the pulpit of Burtnieki church, samples
were taken from parts that were well conserved: the background of the pulpit's
construction, the podium's decorative ledge, the decorative grapes, the roof,
and the pelican. The results of the analysis show that the pink background
contains hematite and occasional particles of calcium carbonate (CaC03) in
oil (Fig. 4). Colors from the original marbling are revealed in the background
(smalt, indigo, hematite, charcoal black, and copper resinate). Decorative elements
are silvered, such as the silver leaves, which were glazed with copper
resinate over the pink underlayer (hematite, oil).
Figure 4. Cross section if paint sample from
part if the podium in the Burtnieki church.
The layers are as follows: (1) thin pink
ground, (2) layer of silver leaves, (3) green
layer containing cupric resinate, (4-8) overpaints.
Photograph by M. B. Vanaga and
R. Kanins.
The decorative bunch of grapes is painted in a dark blue layer containing
indigo, smalt, and oil, and the green leaves are executed in a green glaze
(copper resinate, oil, gum) over silver leaf applied in an oil-based mordant
technique. The decorative details of the pulpit's baldachin have the same
preparatory ground layer as the podium. The marbling is carried out as described
above. The silvering is done using an oil mordant and subsequently
glazed. In some places the silver is covered with colorful glazes (i.e., the drops
of blood on the pelican are executed in an organic red glaze on silver). In
summary, the decorative painting of the Burtnieki church shows a rich polychromy
and is executed in an oil medium.
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Historical Painting Techniques, Materials, and Studio Practice