Colour Grounds of French Baroque Painting

Main R. Duval, Les preparations colorées des tableaux de l’école francaise des dix-septième et dix–huitième siècles, Studies in Conservation 37, 1992, p. 239-258.

The study of basic importance contains detailed data on the composition of "coloured" ground layers of 155 pictures by 17th and 18th century French artists. The author is a physicist and works in the Research Laboratory of the French Museums in Paris. The method of research conforms to his specialization. The composition of the ground was studied on cross sections on a raster electron microscope and by X-ray micro-analysis with additional analysis on a optical microscope. The object of the study was only the "coloured" ground layers. That means that in the case of a two-layered ground with a top grey one the analysis was limited only to the lower layer. This complicates an assessment of the influence of a toning ground on the optical construction of the picture.

The study contains diagrams that give a percentage share of the individual elements of the ground at certain periods and a chronological survey of colour and a detailed composition of the work of 57 masters that were examined. No attention was paid to the relationship of colour of the ground layer to the character and style of the painting, perhaps because red colour was dominant. Yellow and brown are the exceptions. The red ground was used not only on canvas but even on wood (Fragonard, Rivalz). A potential second, grey layer of the ground might have changed the statistics considerably. Three categories of "colour" pigments were found:

1) brown earth, with little iron oxide but rich in siliceous minerals (rare occurrence),
2) red and yellow ochre, often in combination with chalk, lead white, minium and barytes,
3) pure ferric oxide.


Relative distribution of the individual elements: 38 % of the grounds contained only colour pigments, 27 % colour pigment with chalk, 7 % with lead white, 17 % with chalk and lead white, 10 % with chalk and minium, 1 % only minium. Which means that the colour ground contained chalk in varying quantities 54 %. The admixture of chalk is characteristic especially of the first half of the 17th century (E. Le Suer: as much as 90 %!) Lead white was found in 24 % of the pictures, but mostly in small quantities that could have no influence on the tone of the ground. That means that it had a siccative function, as the sources recommended (T. de Mayerne) for the oil grounds. A similar function was fulfilled by the admixture of minium, found in 11 % of the works. According to period sources litharge was likewise used as siccative. Oil medium of the ground always contained siccatives. At the National Gallery in Prague we reached similar conclusions – with regard to the admixture of lead white – in our investigations of Italian Baroque painting.

In referring to the mineral phase, i. e. an admixture of natural origin, the author says it is very variable. Most frequent is siliceous oxide (as much as 50 %), then argillaceous oxide (24 %), ferric oxide (20 – 30 % in grounds of pure ochre). Even small admixtures amounting only to a few per cent were traced. Of these the most frequent were potash and calcite.

A surprising feature is the intentional addition of barium sulphate in grounds containing pure red ochre. Barytes will have been used as a cheap complement to the relatively expensive pigment. The occurrence of this admixture is limited to Paris and to the period between 1620 and 1680 with the most frequent occurrence (50 %) in the years 1640 -1660. The preparation of the ground will have been the work of specialized workshops. Pure red ochre was popular especially in the 18th century.

The study contains very valuable comparative material that fills major gaps in historical technology.

  ELISABETH SCHEEL: DER TEXTILE BILDTRÄGER,
in: Restauratorenblätter Bd.13, Wien 1992, pp.69 - 77

The Restoration Studios of the Federal Bureau for Cultural Heritage in Vienna have been making a collection for 30 years now of the edges of fabrics (usually with the base), roughly 2-3 cm in size. Part of the studied material on canvases records for the first time a published survey made up of 38 pictures painted on canvas. Most of the work is Austrian from the period from the end of the 15th century to the end of the 19th century. The author first gives us a survey of the types of textile fibres and their natures, describes the technique of twisting the thread and spinning. She also covers the further processing of the material, the weaving of the canvases and the method of stretching on auxiliary frames. She draws attention to the pattern of the threads with auxiliary frames which shows a later change of size.

In the article, which concentrates solely on textiles and is certainly necessary, I miss to a certain extent cooperation with an expert restorer who deals with the study of historical painting techniques. A record of the grounds used would be extremely useful. It is also a pity that the author could not publish microshots of the relief of the painting from Central Italy (Rome, Bologna) from the 17th century which she mentions. Very thin canvas was used (Netzleinwand) and the painting formed the characteristic pillows. (p.74). Paintings in Holland and the Lower Rhine on very fine canvas come from the period around 1500. They are without ground, merely sized (known as fasting cloths, Tüchlein, or drafts for tapestries), executed in aquarelle technique. Studying the relationship between the type of canvas used and the painting technique may be a considerable help to art science - this concerns precise dating, irreplaceable in determining the age and authenticity of paintings.

  author
akad. mal. Věra Frömlová