As Sir Ernst Gombrich so clearly pointed out, the Renaissance in northern Europe primarily used oil paints to explore light, form, and texture. This is perhaps first fully expressed in the mature works of Jan van Eyck, and further developed by the likes of Dürer and Lucas Cranach the Elder, among a long list of great and lesser Masters.

My previous article has, I hope, put flight to any remaining ideas that Vasari’s claim of the van Eyck brothers somehow ‘inventing’ oil painting, or even ‘discovering’ some key ‘secret’ which somehow transmuted their paintings. Yet in many books, Jan van Eyck’s mature style and its technical basis remains a major goal, together with those of Rembrandt and others.

Professor Max Doerner’s 1933 revision of his book The Materials of the Artist remains the basis for much popular belief about van Eyck’s techniques, and his ideas are still repeated in much more recent books on oil painting. More extreme views were held, propagated and published by Jacques Maroger (1884-1962), and his pupil Franklin H Redelius, who summarised them in his book The Master Keys (2009).

Doerner, Maroger, Redelius, and their like, base their arguments on various old manuscripts providing painting recipes, such as those of Theophilus Presbyter and Sir Théodore Turquet de Mayerne, their own visual examinations of the surface of some of the paintings, experiments in trying to replicate methods, and reasoning which often seems drawn more by its goal than conducted by rational thought. Their writing is peppered by presumptions, and rich in woulds and mights.

Since the 1950s, increasingly sophisticated physical and chemical methods of studying paintings have come into use. Although their results need careful interpretation, they have shattered previous illusions. For example, Max Doerner claimed that the mature paintings of Jan van Eyck were made using a mixed tempera-oil technique, in which layers alternated between heightening with “tempera white”, and “resin-oil-colour glaze thinned with varnish or balsam or sun-thickened oil” (which must “must be very lean and very finely distributed”). Later Redelius claimed that van Eyck’s main painting medium was “varnish pomade” consisting of egg yolk mixed with linseed oil and mastic resin.

In her review of a wealth of technical studies undertaken on Jan van Eyck’s paintings, Noëlle Streeton concludes that “there is no evidence that van Eyck applied tempera underlayers to paintings that have undergone media analysis to date.” Furthermore, earlier conjecture that egg-oil emulsions might have been used by van Eyck have been soundly rejected: it turns out that they were misinterpretations of evidence of lead soap formation in the paint layer, which formed over time and was not applied by the brush of the painter.

Although Streeton raises many questions about the materials and techniques used by van Eyck, there can be no doubt that his mature paintings were made using linseed oil, both untreated and pre-polymerised by heat, with and without the addition of pine resin, and sometimes siccatives including lead.

Van Eyck’s techniques were modified to take into account the properties of different pigments, and according to the size of the painting. Small panels such as the Madonna and Child at the Fountain (1439) were still painted in layers, using glazes and opaque paints as appropriate, and there is no evidence of any ‘secret’ formulae, nor of any significant departures from the established practices of oil painting at that time. As Ashok Roy has stated, van Eyck’s masterworks primarily result not from technical secrets, but from the extraordinary skills of the painter.

Lucas Cranach the Elder (c 1472-1553) has been the subject of extensive and intensive research, although Doerner, Maroger, and Redelius appear to have little interest in his methods or techniques. Aided by full sets of records for his workshop, technical analyses of his paintings have been able to give very detailed insights into his materials and methods. Cranach’s workshop was unusually large and active: in 1520, it was granted the authority to be Wittenberg’s pharmacy, and he sourced his materials in bulk from Leipzig, Frankfurt am Main, and even Strasbourg.

Cranach’s primary, and perhaps only, drying oil was linseed. There is evidence that this was sometimes used following pre-polymerisation using heat, although that is not generally the case. He also used siccatives occasionally, with traces of copper salts being found in some layers in which they could not serve any purpose as pigments. He appears in some situations to have added finely-ground glass as a thickener and siccative, a practice which has been observed occasionally in van Eyck’s paintings too.

He seems to have been sparing in his use of pine resin, though, with traces being found in only a few paint samples from his work. By 1500, organic solvents, including distilled spirits of turpentine, oil of lavender, and naphtha, were much more readily available, but there are no records relating to purchase of any of them. Their use is also almost impossible to detect in paint samples, unfortunately.

Most of Cranach’s paintings start with an underdrawing made using a brush charged with carbon black ink, although some paintings were started with black chalk or silverpoint underdrawings. Many of his early paintings lacked any undermodelling, but later in his career this became more common, normally using grey, and in the 1540s he changed his practice in his larger works to undertake a full grisaille for all parts. This may have allowed members of his workshop to take over more of the painting without his direct involvement.

Cranach specialised in the realistic portrayal of flesh, the modelling of faces, and had an extensive repertoire of techniques for depicting fabrics and clothing very realistically, and in keeping with the fashion of the day. Heydenreich explores in detail some of those tricks and techniques. Cranach was also adept at mixing passages of enamel-like smoothness with broken marks and visible brushwork.

His modelling of flesh and its toning is particularly complex and varied even within individual paintings. These can involve multiple layers, including traditional glazes, very simple layer structure coming close to alla prima, even wet-into-wet techniques which might be used to add eyebrows quickly.

Although previous studies have led to the conclusion that Cranach used a fixed sequence of painting, all recent research points to him progressively working up the whole panel, rather than bringing individual details to completion.

He had a reputation for being quite an impulsive and rapid painter, which seems to be borne out by analysis of his works. His early works, in particular, show evidence of repeated adjustments in form and colour – which contrasts with Dürer’s much more determinate workflow, for instance. The infra-red reflectogram of the Martyrdom of Saint Catherine shows how he laid down the figures in detail in the underdrawing, but extemporised the pyrotechnic effects.

There were, though, considerable changes made to the details during the painting process, as seen in the underdrawing of the executioner, and the figures to the right of his head.

The conclusions from this extensive research can only echo Ashok Roy’s opinion on Jan van Eyck, that the brilliance of Cranach’s paintings reflects only his extraordinary skills as a painter.

References

cranach.net a massive research database with many visible light and other images. Requires registration. (German)
cda the Cranach Digital Archive, another huge research and image resource, in English or German.

Heydenreich G (2007) Lucas Cranach the Elder, Painting Materials, Techniques, and Workshop Practice, Amsterdam UP. ISBN 978 90 5356 745 6.
Streeton NLW (2013) Perspectives on the Painting Technique of Jan van Eyck, Beyond the Ghent Altarpiece, Archetype. ISBN 978 1 9049 8270 8.