The pretended invention of oil painting and varnish by Jan van Eyck is one of the most influential narratives in Giorgio Vasari's collection of artists’ lives. Discussed critically early on, today there is no longer any doubt that this story is only a myth. Scholarship has provided ample evidence for the use of oil and varnishes in pre-Eyckian painting and polychromy. However, the mostly poor state of preservation makes it difficult to perceive the original effect of varnishes and glazes in artworks. The question of what actually characterizes the materiality and function of varnish and glaze before Van Eyck and how this differed from Van Eyck's concepts is at the centre of Marjolijn Bol's study.
Based on the hypothesis that the older artists aimed at a ‘material mimesis’, whereas Van Eyck strove for the ‘mimesis of the visual world’, she argues that these divergent goals required the development of different types of varnishe and glaze as well as different application techniques. The author develops her argument through a methodically original approach. She does not start from the objects – she cites only occasionally published art-technical analyses – but from art-technological sources dating between around 800 and the sixteenth century. Her text analysis focuses on materials, application techniques and information on their intended effects. Historically informed reconstructions help the reader to understand the physical nature of the respective varnish or glaze, its colour, viscosity and optical properties. This methodological link between text study and hands-on experiments enables Bol to identify changes in physical properties and application techniques and to reveal their impact on the optical effects of the respective techniques.
The introduction offers an outline of the methodology, an explanation of basic physical and optical principles and a definition of certain terms used throughout the study. Chapter 1 focuses on Vasari's narrative of Van Eyck's varnish, its context and reception. Starting with a modern definition of varnish and a short technical overview on the principal varnish types, the second chapter is mainly devoted to published sources on varnishes conceived before 1450. The texts are presented and roughly contextualized according to current research. From the evaluation of the recipes, Bol concludes that the painters of this period primarily used varnishes to enhance the brightness of paintings and the lustre of metals. This was achieved with highly viscous varnishes applied in several layers. Yellow-coloured coatings served to add lustre to gold surfaces or to make silver and tin look like gold. Protection of the painting seems to be a secondary effect. An excursus on the terminology of vernix (varnish) leads Bol to analogies between painting and cosmetics in medieval literature.
Chapter 3 deals with the changes in composition, viscosity and application technique documented in recipes of the second half of the fifteenth century and in the sixteenth. Based on textual analysis combined with reconstructions, Bol notices a shift towards colourless and thinly applied varnishes, which were primarily used as protective coatings.
Turning to the glazes in artworks before the fifteenth century, Bol introduces a cross-media perspective (Chapter 4). The high medieval key terms perspicuus and translucidus indicate a close semantic relationship to concepts of precious stones in contemporary natural philosophy. Bol argues convincingly that there was a mutual influence between material imitations of stones, material mimesis and theories of natural philosophers on minerals and optics. Imitating gems, coloured glass, enamel and even the glow of silk on different supports is defined as a primary function of glazes before the fifteenth century (Chapter 5). The analysis of recipes and reconstructions helps to understand different effects of coloured varnishes and coloured glazes.
In Chapter 6 Bol contrasts this concept of ‘material mimesis’ with Van Eyck's concept of the ‘mimesis of the visual world’. In describing Van Eyck's innovations, she draws on a hypothesis of Ernst Gombrich, who already recognized the use of highlights as an essential element of the illusionistic effect of Van Eyck's paintings. Bol argues that the representation of specular reflection is not dependent on the technique of oil painting, on glazes or varnishes, but that it could be applied according to a codified modelling system also in other media, including tapestries. In this modelling system, described much later in De Beurs's 1692 De groote waereld in ’t kleen geschildert, glazes and varnish no long evoke translucent materials but rather enhance the saturation of opaque paints.
Given the importance of terminology for the argumentation, it is regrettable that the discussion of terms is rather unsystematic and the citation of the sources methodically problematic. In the case of Latin texts, the reduction of original quotations to single-word snippets leads to a confusing variety of grammatical forms of the same word. A systematic discussion of terminology would have been better based on the nominative case, with full original citations as reference. The mixing of English paraphrases and declined Latin words complicates the understanding of shifts of meaning. Occasionally the author herself seems to be confused and considers the ablative of vernix (vernice) as a new term (p. 78, 81, 85 ‘called vernice’). In the latter case, the Hortus sanitatis, the whole sentence is misunderstood – vernix is the end product (varnish) and vernice (the ablative of vernix) the ingredient, and not, as proposed by Bol, the other way round. Similarly strange appears the etymology of glatsieren, traced back to glatt (smooth) and sieren (to decorate), although all cited parallels in French and German allude to glass and ice (pp. 186 f.).
Despite these minor objections regarding philology, Marjolijn Bol's book offers valuable new insights into the function and perception of varnish and glaze in medieval art. The combination of text study and reconstruction, supported by excellent illustrations and diagrams, proves to be a particularly fruitful approach.
