In 1989 restorers Jiří Třeštík and Tamara Beranová began the investigation and restoration off figural drawings beneath the panel paintings in the Holy Rood Chapel of Karlštejn Castle. The detailed restorer's investigation aimed at a compiling of all the accessible facts concerning the drawings, their classification and consistence with already published knowledge about the decoration of the Holy Rood Chapel and painting during the reign of Charles IV generally, providing thus an exact basis for speculation on the meaning and dating of the drawings. This aim was exceeded when the restorers, together with Dr Hana Hlaváčková and Dr Zuzana Všetečková, discovered three figural drawings unknown until then. These are: one semifigure with a cross, the Holy Virgin with Child and one Holy King.

Attention was paid to the stratigraphy of layers, to extent and reason of a grey overpaint found on the northern altar wall and even under the drawings proper, together with pigments and binding media used, the relationship of the drawings to the grey overpaint and the plaster, and also to the grill bearing the panel paintings. The problem of painter's signs was also considered.

The investigation was done with the help of mechanical probes, infra-red photographs 1 and an analysis of samples taken from the drawings in a chemical laboratory of the National Gallery in Prague. Cross section of ground layers and drawings were also evaluated A careful visual investigation of enlarged photos of the drawings was also part of the work.

Results of the investigation:
The drawings rest on a coarse lime plaster without a stucco layer, applied in horizontal stripes gradually from above. The liniking of individual stripes is well recognizable, they are joined aross the drawings. The plaster is aid irregularly, the surface being quite granulated in some places, while in others, where the mass of plaster was stressed more, the surface is smooth (a whitish layer near the surface of the plaster, composed of a  surplus of calcium carbonate, can be seen under the microscope it the samples taken from these places). The plaster is not covered by any of the two ground layers used for the wall paintings in the Holy Rood Chapel 2. In the course of restoration works, repairs of damaged spots were found, done either by an older modern filler, similar in colour to the original plaster (only more permeable), or by a younger modern filler of grayish colour, reaching often far beyond the limits of the defects in the plaster layer. The coherence of these fillers was very limited.

The gray overpaint was noteced on the northern altar wall of the chapel in three squares of the lower horizontal line and, to a smaller extent, also in the two squares bordering on the first ones from above. The first square to the left of the altar, under the panel with St John the Baptist, and the third square to the left of the altar, under the panel with Apostle Philip, were wholly overpainted. The second square to the left of the altar, with the drawing of St Andrew, is covered by the overpaint approximately to four-fifths. The drawing of St Andrew is executed in a grater part on this overpaint and in a lesser part directly on the plaster.

Chemical analysis showed that the grey overpaint is a mixture of natural chalk and gypsum and is pigmented by fine carbon black. An iodine test proved that a great amount of starch grains is present; the material seems to be arye starch 3.

Over the grey overpaint several sings and numbers are written. These are: In the first square to the left of the altar are the numbers 3 – and 4. written in white chalk, No. 3 is carossed out with the same chalk. No. lois written with a brush in brown colour.

Over the paint covering the third square to the left of the altar, a painter s sign is drawn with brush in black colour a human profile (chemical analysis proved it to be carbon black bound by a proteineous medium. Further, the name »Phillippus« written in Gothic minuscule (carbon black), number 1 written in white chalk and the number 14 written with a brush in brown colour were found.

Over the paint covering approximately four-fifths of the second square to the left of the altar, number 2 is written in white chalk and N 15 by brush in brown colour. The grey overpaint here forms the greater part of a ground layer for the drawing of St Andrew, executed in a greater part over this paint and in a lesser part directly on the plaster.

In all the places where it could be verified, we found the grey overpaint covering the figurai drawings of the invalid lines between individual squares, whose division was searched for, changed and given precision only in the course of the work. e. g., in the first square to the left of the altar, a drawing of the Holy Virgin with Child was found under the grey overpaint, and in the third square to the left of the altar a drawing of a half figure with a cross. In the square bordering from above on the squares with the drawings of St Andrew and the Virgin Mary with Child, the grey overpaint covered the invalid division lines of the squares. A hypothesis based on these findings says that there is a possibility of finding another drawing under the overpaint, over which the drawing of St Andrew is partially executed. The hypothesis cannot be verified because a probe large enough to catch and uncover to (a necessary extent the subtle linear drawing would have to be so extensive, that it would damage the drawing of St Andrew. The grey overpaint is impenetrable for infra- red photography.

The acquired knowledge enables us to form a judgment on the function of the grey overpaint. The idea of the decoration of the Chapel was specified only in the course of the work on the drawings, the artist was looking here for the layout of the decoration, their measurements proportions. The grey overpaint enabled him to make corrections, to cover the invalid division lines or drawings, whose location or measurements were not in accordance with the final arrangement or idea.

Further facts ensue from the results of the investigation: The investigation showed that all drawings, with the exception of St Andrew, run in their lower parts behind the lower horizontal beam of the grille carrying the panel paintings.


Drawing executed directly on plaster, uncovered

2 drawing executed directly on plaster, covered by the grey overpaint

3 drawing executed over the grey overpaint

ikonographia:
1/ St King,
2/ Saint with a cross,
3/ St Andrew,
4/ Holy Virgin with Child,
5/ St John the Baptist,
6/ St Peter,
7/ St Paul,
8/ Holy Bishop

distribution of the grey overpaint >>>>>>>>>>>>>>

St Andrew, drawing under the panel with St Peter detail after restoration. Photo Kamil Wartha.

The drawings cannot be wiped off, only the base layer of the drawing of St Andrew is less resistant to mechanical damage. Diring a visual investigation of the enlarged photographs, brush strokes done in black colour are very clear in some places.

The laboratory analysis proved that the black pigment used in the drawings and the painters sign under observation the sign in the square with the Ho ly King, the sign of a human profile in the square with the newly discovered drawing of a semi figure with a cross and the inscription »Phllippus« in the same square) is carbon black. The analysis exvluded any presence of both lead and silver. An analysis of the white colour proved that it is natural chalk (fossile shells of microorganisms, the cocolites, can be clearly seen under the microscope). The analysis also decided that the brown colour used to draw the Holy Bishop is composed of red and yellow ochres, finely granulated and reminiscent of bolus 4.

Lights drawn in chalk were found also in the newly discovered drawings. In the case of the semi figure with a cross and the Holy Virgin, the lights were found under the grey overpaint, only a painter's sign was drawn over it in the square with the drawing of the semi figure with a cross. This fact refutes a suggestion that the lights could have been added later to the drawings originály executed only in black colour.

All these facts support the opinion that the drawings originated as draft drawings. In 1992 the restoration will continue: the investigation will be finished (in collaboration with Dr. Hlaváčková and Dr. Všetečková), the drawing of the Virgin Mary will be uncovered and restored and the drawing of the Holy King will be restored.

  author
Jiří Třeštík, AHVT B 019

The Holy Chapel. Newly discovered praparatory drawing of the semifigure with a cross, under the panel with Philip Apostle (northern wall of the chapel, the lower row, 3rd square left of the altar). On the left initial removal of layer, photo IR standard; on the right – state after restoration

1 A. Krejčí of VÚZORT Institute, Prague, executed the infra-red photographs of the newly discovered drawings.

2 Mojmír Hamsík – Jindřich Tomek, Technické paralely deskové a nástěnné malby 14. století. Umění XXXI (1983), s. 308-16.

3 D. Pechová mentions in an appendix to her laboratory report that the presence of starch grains was proved also in the grey siliceous ground layer of the wall paintings on the northern and southern side of a window edicule in the Holy Rood Chapel, and also in the grey siliceous ground of the panel paintings by Master Theodoric and in the filling of some of the pastiglia. The plastic decoration of the southern side of a South-East edicule contains starch granules, too. Presumably, this is a rye starch.

4 Brown colour is used to a smaller extent also in the drawing of St John the Baptist.

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