Introduction

This chapter lays out a conservation timeline, from past to future, for the Amsterdam version of Van Gogh's Sunflowers. It starts by considering the restoration history of the painting in order to assess its current physical state, and looks ahead to formulate an appropriate strategy for future conservation treatment and display. Due attention is paid to the two recorded episodes of restoration performed in 1927 and 1961 by the Dutch restorer, Jan Cornelis Traas. Based on physical and chemical investigation of Sunflowers we attempt to reconstruct what these former treatments (which are barely documented) entailed and consider the repercussions for the present condition of the painting. The former interventions by Traas also serve as a benchmark to reflect on current choices made, highlighting the extent to which ideas and methodologies have continued to evolve over the past century as conservation has moved further away from being a singularly craft-based activity to become an established historical and scientific discipline underpinned by ethical guidelines.

Jan Cornelis Traas (1898–1984)

As mentioned, the two main recorded interventions to the Amsterdam Sunflowers may be associated with the Dutch restorer, Jan Cornelis Traas, who treated the picture in 1927, close to the start of his career, and again in 1961, shortly before he retired. Traas was the first restorer to be appointed at the Mauritshuis in The Hague where he worked from 1931 to 1962 and treated hundreds of paintings, including iconic masterpieces such as Girl with a Pearl Earring by Johannes Vermeer. Yet despite the magnitude and importance of his restoration oeuvre, J.C. Traas (as he is usually referred to in surviving documents), has remained somewhat obscure. He is shown here in the only known surviving photograph of him at work, shortly before he retired (fig. 7.1). Unlike his illustrious contemporaries, A. Martin de Wild (1899–1969) and Helmut Ruhemann (1891–1973), for example, Traas did not publish anything, he appears to have kept no records of his work and no personal archive is known. However, the study of some newly discovered historical documents, combined with physical examination of Sunflowers and a large number of other works he treated, allows us to recover an idea of his working practices and approaches viewed within the context of his day.

Introduction

Since its completion by Vincent van Gogh, the Amsterdam Sunflowers has been the subject of a complex history of interventions. Combined with the natural ageing and deterioration of the materials used by the artist, this has strongly affected the present appearance of the painting. The materials and techniques used in Sunflowers and related colour changes have been presented in chapters 4 and 5. This chapter focuses on characterizing the non-original surface layers present as well as secondary compounds arising from pigment-binder interaction in original paint components. The outcomes of this research help to reconstruct the restoration history of the painting and to understand its present condition, as a basis for optimizing future conservation treatment (as elaborated in chapter 7).

In keeping with Van Gogh's usual practice in the period, he left Sunflowers in an unvarnished state. Today, however, multiple layers of varnish are present. These have yellowed and make the painting appear highly glossy, whereas originally it presumably had the more subtle satin gloss related to pure oil paint. Conversely, some areas of the painting now look matt, since wax has been locally applied in the past.

Historical records provide sparse information regarding the surface layers added during earlier campaigns of treatment (see chapter 7). We know that the painting was varnished in 1927 by the conservator Jan Cornelis Traas, as part of a broader restoration and structural (lining) treatment. Remains of paper tape on the tacking margins of the painting are believed to date from this period (see chapter 7, p. 184). Further documents record that in 1961, Traas worked on the painting again. However, as there is no known account of what this treatment entailed, it remained in question whether Traas removed the 1927 varnish and/or applied new surface coating layers instead. Furthermore, in the late twentieth century, wax was applied in certain areas, used to matt down the glossy varnish and/or impregnate and consolidate the ground.

This chapter describes the outcome of the technical examinations of the Amsterdam Sunflowers, characterizing the surface layers present and assessing the history of application as revealed by their stratigraphy and chemical composition.

Introduction

This chapter provides a description of colour changes in the Amsterdam Sunflowers due to chemical alteration of pigments, with a focus on geranium lakes and chrome yellows.

The brilliant and forceful colours of these and other late nineteenth-century synthetic materials offered artists such as Vincent van Gogh new means of artistic expression that exploited a range of contrasting hues and tints. However, geranium lakes have a strong tendency to fade and chrome yellows to darken under the influence of light. Van Gogh, like other artists of his day, was aware of this drawback, yet he continued to favour the use of both pigments up until his death in July 1890 due to the unparalleled effects they gave. In April 1888, Vincent wrote to his brother Theo:

Van Gogh's use of unstable colours opens a series of questions regarding the extent to which colour change affects the way his paintings look today, as discussed here in relation to the Amsterdam Sunflowers. Furthermore, given the frequency with which geranium lakes and chrome yellows occur in Van Gogh's paintings of the period 1888–90 and the predominance of chrome yellows in Sunflowers, it becomes important to understand the factors that can drive these processes of deterioration in order to develop appropriate strategies for conserving the artist's works.

Introduction

This chapter explains the materials and techniques employed in the Amsterdam Sunflowers, enabling a comparison with the London version described in chapter 3. Building upon the 2016 article published in the National Gallery Technical Bulletin, it incorporates the latest findings gained by computer-assisted methods used to characterize the canvas support, as well as in-situ campaigns of non-invasive investigation together with further analysis of microscopic paint samples. The chapter sequence follows the steps in Van Gogh's working practice. Starting with the canvas, automated analysis of the weave enables the provenance of the canvas to be traced back to a particular roll of linen ordered by Van Gogh. Combining technical evidence with knowledge of historical manufacturing techniques further allows us to reconstruct the way in which Van Gogh divided his canvas roll into pieces used for Sunflowers and other paintings. We go on to consider how, with the original painting at hand, he used charcoal to transfer the motif of the London Sunflowers onto his blank canvas. Despite careful planning of the composition, an adjustment was required late in the working process, when Van Gogh added a painted wooden strip to extend the background above the flower at the top edge of the canvas. The artist's process of working up the composition in paint is described, paying special attention to his use of colour. The pigments and pigment mixtures used in the Amsterdam Sunflowers have been comprehensively mapped and are compared with the London picture, with discussion of some similarities and differences that account for the distinctive colour scheme of each painting. This understanding of colour application in the Amsterdam Sunflowers lays the foundation for subsequent chapters that will go on to consider the impact of light-induced colour changes that have taken place over time, and the related need to define appropriate lighting guidelines for the future safe preservation of this painting and others made with similar materials (chapters 5 and 7).

Canvas

Studying the physical characteristics of canvas picture supports is an established means of acquiring valuable information about a painter's working methods. The canvas itself is hidden by paint on the front and a second canvas is often applied to its reverse for added support.