Exploring the Materiality of Powdered Colours: a Seminar on Pastels

The seminar, held from 25 March to 3 April 2025, was organised by the Centre de Recherche pour la Conservation (Paris), the University of Amsterdam, the Rijksmuseum and the University of Chicago, and was supported by the Getty Paper Project. Nearly twenty curators, conservators and conservation scientists from a number of countries participated in the programme.

Prominent collections

In the eighteenth and nineteenth centuries, artists were drawn to pastels for their brilliant colours and powdery textures, as well as for the ease and speed with which the medium could be used on location. Eighteenth-century portrait artists travelled from court to court to make portraits of the prominent figures of their time. In the nineteenth century, artists started to draw public life, away from the studio, and benefitted from the unparalleled brilliance of pastel colours.

During the seminar, the participants visited the extensive collections of the Rijksmuseum, the Museum Antoine Lécuyer and Musée d’Orsay, studying and comparing the materials and techniques used in eighteenth- and nineteenth-century pastels. At the Van Gogh Museum, pastel works by artists including Jean-François Millet, Paul Gauguin and Odilon Redon were closely examined. The participants delved into the complex artistic techniques andindividual use of the medium, but also into issues related to identification, discolouration, framing, preparation, and the special supports.

The (historical) production process

Pastels have traditionally consisted of the same basic ingredients: pigments and/or colourants, filler and a little binding agent. The fixatives and the paper also need to possess specific qualities, which were achieved using various materials and techniques. The seminar participants learned a great deal about the production process during visits to De Schoolmeester paper mill, De Kat paint mill and the Royal Talens factory in Apeldoorn, where both paint and pastels are produced on an industrial scale.

At the opposite end of the spectrum stands the world’s oldest pastel manufacturer: La Maison du Pastel, where artists’ pastels have been handcrafted since the early eighteenth century. During a practical session, participants compared the properties of various pastels and created their own using different compositions and preparation methods, which may also serve as a reference set in the future.

Technical research

This seminar also introduced the wide range of methods and tools that are now available for use in technical research into pastels. Reflectance spectroscopy and hyperspectral imaging are two non-invasive techniques that were demonstrated in detail at the Centre de Recherche sur la Conservation des Collections (CRC).

These techniques assist in the analysis of the pigments and colourants used, along with the fillers, binders, support materials, and fixatives. The advantages and disadvantages of the two techniques were discussed, leading to the conclusion that combining them provides the most comprehensive insights.

Transport, lighting and presentation

Another draw of pastels in the eighteenth and nineteenth century was the ease with which they could be transported: they were often carried in carriages over cobblestone roads. Rather ironically, pastels are nowadays rarely allowed to travel for exhibitions. Due to the powdery quality of the medium, so popular with artists, pastels are highly vulnerable to even the slightest vibrations, and exposure to light also impacts the brilliance of the colours.

During the seminar, discussions addressed how to balance the inherent fragility of pastels with a case-by-case approach to assessing loan requests. Attention was also given to the ethical issues associated with loan traffic between museum and private collections. Effective communication and collaboration are crucial, not only in relation to the condition of the pastels, but also for a better understanding of every aspect of this attractive and fragile medium, which has fascinated artists and art historians for more than three centuries.