All posts by mariekehendriksen

Marieke Hendriksen is a historian of science, art, and ideas, based at Utrecht University , The Netherlands. She is particularly interested in the material culture of eigtheenth-century medicine and art, and the transmission of instructions through text. She currently is a postdoc with the ARTECHNE project (

What’s in a name: Plaster of Paris

By Marieke Hendriksen

One of the problems we face as historians studying and reconstructing recipes is that the names describing ingredients, tools, and materials change over time, and that the meaning of terms itself changes over time. This is even the case with relatively recent recipes and materials that are in theory unchanged as I recently discovered. As part of my research for the ARTECHNE project, I recently looked at instructions for making anatomical casts from plaster from 1791.

Painted plaster cast of a large fibroma of the jaw, 1830s. Courtesy Surgeons' Hall Museums, RCSEd.
Painted plaster cast of a large fibroma of the jaw, 1830s. Courtesy Surgeons’ Hall Museums, RCSEd.

The creation of anatomical casts and models using plaster of Paris became increasingly popular towards the end of the eighteenth century, fuelled by the omnipresence of plaster in the visual arts and interior decoration, and the increasing importance of pathology and later physiognomy within the study of medicine. The latter meant that medical men were looking for durable three-dimensional ways to preserve diseased bodies and body parts that could not be preserved otherwise (e.g. in a preparation), either because decay could not be stopped or because the patient was still alive.

Johan Zoffany, The Portraits of the Academicians of the Royal Academy, 1771-72
Johan Zoffany, The Portraits of the Academicians of
the Royal Academy, 1771-72. Note the plaster models of antique statues around the room.

In his 1790 book The Anatomical Instructor, physician Thomas Pole (1753-1829) not only gave advice on how to make anatomical preparations and drawing, but also included over fifty pages on how to create, colour, repair and maintain plaster casts and models. Pole started the chapter on modelling with outlining the relevance of the quality of the plaster of Paris, or calcined alabaster, that was to be used. He explained that

Illustration of how to make a cast of a diseased bone from Pole's 1790 'Anatomical Instructor'
Illustration of how to make a mould of a diseased bone from Pole’s 1790 ‘Anatomical Instructor’

“…that of a middling price is used for making of moulds; the finer sort is for casts, to be poured first into the mould, when properly prepared; after it has formed a layer of about half an inch, more or less, according to circumstances, then the coarser sort is to be used to fill up the mould, or to give it sufficient thickness.”[1]

But exactly what were the various qualities of plaster for sale in London in the 1790s made of? The term ‘calcined alabaster’ tells us little, as alabaster was and is a collective noun that designates both various kinds of light-coloured, translucent and soft stone used mainly for carving decorative artefacts (often the minerals gypsum or calcite – the former much softer than the latter), and a specific compact and fine-grained variety of gypsum. In the decades after Pole’s publication, the French chemist Antoine François de Fourcroy (1755 –1809) would distinguish nine kinds of calcareous sulfate, one of which was sulfate of lime or common gypsum. In an 1810 ‘dictionary of the arts’ Fourcroy’s sulfate of lime or common gypsum was described as follows:

“Sulphat of lime, or common gypsum, or plaster-stone. This substance is white, more or less inclining to grey, interspersed with small brilliant crystals, easily cut with a knife. it is found disposed in Paris. We shall hereafter find, that it is not pure selenite, but owes its most valuable property, as plaster, to the admixture of another kind of earth. (…) Calcareous sulphat is likewise found dissolved in waters, as in the well-waters of Paris; it is never pure, but always combined with some other earthy salt, with base lime or magnesia. This salt has no apparent degree of taste. It decrepitates if a sudden heat be applied to it; it is then of an opaque white, in which state it is called fine plaster, or plaster of Paris: by this calcination it loses about twenty in one hundred.”[2]

Entrance to the Montmartre gypsum quarry. Probably early 19th century, artist unknown.
Entrance to the Montmartre gypsum quarry. Probably early 19th century, artist unknown.

As this fragment suggests, plaster of Paris indeed derives its name from a large and very pure gypsum deposit at the Montmartre and Menilmontant hills in Paris – there were plaster quarries at this site at least as early as the year 500. This led “calcined gypsum” (roasted gypsum or gypsum plaster) to be commonly known as “plaster of Paris”, even after the exhausted quarries were converted into Montmartre cemetery and the Buttes de Chaumot gardens respectively in the mid-nineteenth century. Although not all plaster came from Paris at the time Pole was writing, there is a fair chance that much high-quality plaster was indeed plaster from Paris.

Today, gypsum plaster, or plaster of Paris, no longer comes from Paris, but is still produced by heating powdered gypsum to about 150 °C. When mixed with water, this forms a paste that will harden within minutes, producing an exothermic reaction, which means it warms up. You can easily buy ‘plaster of Paris’ from artist’s supplies shops and online retailers, but none of these mention the exact chemical composition. Yet before I (or anyone else) can try my hand at reconstructing Pole’s instructions I will need to find out whether the best, finest plaster of Paris still contains a percentage of lime or magnesia, what the ‘coarser varieties’ that Pole described contained, and whether these are still available.

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 648718), and was supported by the Wellcome Trust (grant number 203403/Z/16/Z).

[1] Pole, Thomas. The Anatomical Instructor ; or an Illustration of the Modern and Most Approved Methods of Preparing and Preserving the Different Parts of the Human Body and of Quadrupeds by Injection, Corrosion, Maceration, Distention, Articulation, Modelling, &C. London: Couchman & Fry, 1790: p. 202-3.

[2] Wilkes, John. Encyclopaedia Londinensis, Or, Universal Dictionary of Arts. Vol. 4. London: J. Adlard, 1810: p. 230.


Creating and integrating a database – work in progress

By Marieke Hendriksen

As mentioned in the post introducing the ARTECHNE project at Utrecht University last month, we are in the process of creating a database containing recipes, artist handbooks, and art theoretical texts that can clarify the development of the use of the term ‘technique’, as well as related terms referring to processes of making and doing. The database is linked to Geographical Information Software (GIS), thus creating an online historical semantic map of ‘technique’. Such maps are more than merely nice illustrations; they can reveal connections that remain hidden otherwise.

We are in the fortunate position where we can build the database on an existing one, namely the excellent Colour ConText database. However, we do not simply want to offer a copy of the Colour ConText database, we want to integrate it with other sources on artisanal practices and theories, such as recipes, books of secrets, art theoretical texts, and artist handbooks, from the period 1500-1900, in Latin, Dutch, German, English, French, Italian and Spanish. The entire database has to be searchable with advance searches, allowing users to search full text for occurrences of terms, in particular geographical or linguistic areas and periods, or to trace the changing uses and meanings of particular terms over time, linking various forms of terms and different terms with a similar meaning in relational tables and glossaries.

Sneak preview of the new database website
Preview of the new database website

For example, if we want to know how instructions for making paint have changed in the low countries between 1600 and 1900, we want to be able to select all available sources from that period and area and search them for imperatives, nouns, measurements, and particular ingredients. We also want to be able to distinguish between printed and manuscript sources, artist handbooks and household recipes books, and ideally we want to be able to search annotations and marginalia too, as well as differences between various editions of the same work. That means a lot of different parameters have to be specified for each source, and everything we include must be carefully checked before it is added.

One of the problems we encountered when selecting the first sources we wanted to add was the low reliability of Optical Character Recognition software when used on early modern printed sources – a problem I have written about on my own blog before. We do not just want to combine existing digitized sources in our database, but also to add texts that have not been digitized and made searchable thus far. However, that often involves lengthy correction processes. One of the solutions we are considering is crowd sourcing such corrections. Fortunately, we can also add many digitized sources that are available under Creative Commons licenses (i.e. from the Digital Library of the Netherlands), and various researchers have contacted us to discuss adding their own datasets to the database.

The first edition of the database is now online – have a look at!  Please note that this is a first version, and that the database will be improved and continue to grow for the duration of the project. Over the next few months, we will focus on increasing searchability and adding new sources. If you have any questions or suggestions, please contact us at artechne[at]

Finally, we will also explore the options of maintaining the database after the end of the ARTECHNE project, for example by depositing the datasets or even the entire infrastructure with an archival institution.

The ERC ARTECHNE project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 648718) and is a cooperation of Utrecht University and University of Amsterdam.

Introducing ARTECHNE – Technique in the Arts, 1500-1950

By Sven Dupré and Marieke Hendriksen

Gerard Dou, Man Writing by an Easel. c. 1631-32. 31.5 x 25 cm, oil on panel. Private collection
Gerard Dou, Man Writing by an Easel. c. 1631-32. 31.5 x 25 cm, oil on panel. Private collection

What is ‘technique’ in the visual and decorative arts? And how is ‘technique’ transmitted? Those are the central questions of ARTECHNE, a five-year project supported by the European Research Council, and led by Sven Dupré, that started at Utrecht University and the University of Amsterdam in September 2015. ARTECHNE is the acronym of the project. Its full title is “Technique in the Arts: Concepts, Practices, Expertise, 1500-1950”.

To answer these questions an interdisciplinary team of researchers with backgrounds in history of art, science and technology, based at the Descartes Center for the History and Philosophy of the Sciences and the Humanities in Utrecht umanitiesworks together with conservators and conservation scientists at the Atelier Building / NICAS in Amsterdam.

One aim of the ARTECHNE Project is to write the history of the conservation studios or laboratories and the research uniting conservation, art history and science in the Atelier Building. This field of research (or is it a nascent discipline?) is now often called technical art history.

‘Technique’ is a fundamental concept in technical art history, but its meaning has evolved over time. By providing a history of technique in the arts, the ARTECHNE project will help to reflect on both historical and current knowledge practices in technical art history, conservation and restoration. For example, one of the four sub-projects focuses on the ways in which new visualization technologies and science-based methods (such as X-rays, black-and-white photography and chemical analysis of paint cross sections) shaped art history and conservation practice in the first half of the twentieth century.

Daniel V. Thompson's 1954 translation of Cennino Cennini's Libro dell'Arte.
Daniel V. Thompson’s 1954 translation of Cennino Cennini’s Libro dell’Arte.

The ARTECHNE Project starts from the observation that the transmission of ‘technique’ in the arts has been a conspicuous ‘black box’ resisting analysis. The tools of the humanities used to study the transmission of ideas and concepts are insufficient when it comes to understanding the transmission of something as non-propositional and non-verbal as ‘technique’.

Therefore, one sub-project, in which PhD candidate Thijs Hagendijk works closely together with conservation and restoration specialists at the Atelier Building, undertakes the experimental reconstruction of historical recipes to open the black box of the transmission of technique in the visual and decorative arts. The aim of these reconstructions is understanding the textual culture of the early modern workshop and the role of recipes in practices. Did early modern people learn from texts to do things? And if so, in which ways did they use recipes? We primarily look at artisans, but this was a hybrid identity at the time.

The historical sources of the ARTECHNE project are foremost recipes, or how-to instructions. We should also reflect on why and how these sources have come down to us. Jenny Boulboullé in her sub-project investigates the creation of editions and translations of premodern and early modern texts, such as the editions and translations of Cennino Cennini by Mary Merrifield and Daniel Thompson, in the nineteenth and early twentieth centuries. While such editions are still used by conservators and restorers today, one point of attention in ARTECHNE is the role of conservation and restoration projects, painting practice and reconstructions in these editorial projects.

Finally, in response to one of the main questions driving the ARTECHNE Project, Marieke Hendriksen writes a history of the shifting meanings of the term ‘technique’ in the arts and sciences. To support her research and that of the other project members, building on ColourConText hosted at the Max Planck Institute for the History of Science, she will create a database containing recipes as well as art theoretical texts that can clarify the development of the use of the term ‘technique’ – a neologism in the vernacular in the mid-eighteenth century – as well as related terms referring to processes of making and doing. The database (which will be hosted at the ARTECHNE website) will be linked to GIS software, thus creating an online historical semantic map of ‘technique’.

Marieke Hendriksen and Thijs Hagendijk have taken up their posts in the first months of 2016. We look forward to the arrival of Mariana Pinto (from the conservation and materials science program at UCL Qatar) and Jenny Boulboullé (from the Making and Knowing Project at Columbia University)  over the summer, and to earnestly start with the reconstructions in the fall. Tonny Beentjes, leader of the metal conservation program at the University of Amsterdam, and Maartje Stols-Witlox, lecturer of paintings conservation, have joined the ARTECHNE Project. We are still looking to appoint a glass expert. ARTECHNE is supported by program manager Jill Briggeman, who also maintains the website.

This website,, is now online. Over the next few months, we will add more information about the project in blogs, and we list events, like the monthly Technical Art History Colloquium. Sign up for updates on the website and follow us on Twitter! (@ArtechneProject)

The ERC ARTECHNE project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 648718) and is a cooperation of Utrecht University and University of Amsterdam.

How to avoid a bad buy and angry patrons: a recipe for pigment testing

As we have seen in other blog posts before, recipes for counterfeits, imitations, and ersatz products were fairly common in the early modern period. On the other hand, there were recipes to detect the results of such deceit, such as this recipe to determine whether wine had been sweetened with lead or not. This testing of products was not only relevant for consumers and apothecaries, but also for artists, as appears from an eighteenth-century artist’s manuscript I have been studying recently.

Mattheus Verheyden, portrait of Otto Frederick Houttuyn. Was the robe painted with a cochineal-based red?
Mattheus Verheyden, portrait of Otto Frederick Houttuyn. Was the robe painted with a cochineal-based red?

Mattheus Verheyden or Verheijden (1700-1776) was a successful Dutch portrait painter. The son of the painter Franck Pietersz Verheyden was orphaned at an early age, but thanks to his late mother’s fortune he received training as an artist and soon he became a sought-after painter in the upper classes, and made many portraits of regents, clergymen and royals. In the Rijksmuseum Research Library, a manuscript ‘art and recipe book’ attributed to him is kept (call number 319H17). Written in a neat hand in an unruled notebook meant for music notation, Verheyden recorded almost two hundred pages of recipes and instructions for artists. On the title page he wrote: “Art and Recipe book, for painters and etchers &c., brought together over time and with diligence, by M.V.H.” Some of the instructions come from well-known artists handbooks of the time, while the origin of others is not entirely clear.

From the order of the contents of the book, it becomes clear that the quality of his materials was very important for Verheyden. The first ten pages are devoted to various recipes for making ultramarine paint based on lapis lazuli. Yet they are followed by a recipe that does not describe how to make a paint, but how to test the quality of pigments. It reads:

Verheyden's pigment test. Source: Rijksmuseum Research Library, call number 319H17.
Verheyden’s pigment test. Source: Rijksmuseum Research Library, call number 319H17.

Test, to discover whether the lacquer one uses to paint is good &c. If the lacquer is made of cochineal, it never changes. And if it is made of Brazil wood, &c., it will becomes an orange colour over time. To discover this, take a small grain of lacquer, and rub it with your nail on a piece of white paper, and put a drop of lemon juice on it. Rub it through the lacquer with your finger. If the lacquer remains unchanged, it is good, and made of cochineal. But if it turns an orange colour, it is unstable, and made of Fernambuk, or Brazil wood, and will evaporate over time, and is no good.

Cochineal in crude and powdered form
Cochineal in crude and powdered form
Powdered brazil wood extract. It is not difficult to imagine the confusion.
Powdered brazil wood extract. It is not difficult to imagine the confusion.

Red pigment made of brazil wood was – and is – much cheaper than that made of cochineal. Even today, the latter is four to thirteen times more expensive than the former – crude cochineal sells at about ten euros for 25 grams, and carmine red (purified cochineal) costs about thirty euros per 25 grams, while the same amount of brazil wood pigment costs only about 2.25 euros. The relative instability of brazil wood as a red pigment had been known for centuries, but this recipe gave a quick and relatively easy way to determine whether what was on offer was cochineal or brazil wood.

For an artists like Verheyden, whose reputation depended partly on the quality of the source materials he used for his paints, this was understandably very important. Commercial, ready-to-use paints only became available in the nineteenth century. Although Verheyden’s recipe book never appeared in print as far as we know, it is reasonable to assume that the kind of testing and quality-control described in this recipe was a desirable commodity for painters and other artists who worked with pigments that they bought from apothecaries, herbalists, chemists, or traveling salesmen.