Writing the Biography of a Notebook: interpreting a richly decorated baroque notebook from the collection of the Rijksmuseum Amsterdam

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Writing the Biography of a Notebook

Interpreting a richly decorated baroque notebook from the collection

of the Rijksmuseum Amsterdam

MA thesis

Conservation and Restoration of Cultural Heritage: Technical Art History

Student: Anneke Hoekstra Student number: 10454780

Thesis supervisor: prof. dr. H.H.M. (Erma) Hermens Second reader: dr. H. (Herman) den Otter

Word count: 17992

University of Amsterdam, Amsterdam July 2020

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Abstract

Juli 2020,

Anneke Hoekstra (10454780)

In het interdisciplinaire MA-scriptieonderzoek aan de Universiteit van Amsterdam ‘Writing the

Biography of a Notebook: interpreting a richly decorated baroque notebook from the collection of the Rijksmuseum Amsterdam’, fungeert het object BK-17172 als primaire bron. De ‘levensloop’ van

het object wordt onderzocht, om te achterhalen hoe, waar en wanneer het is vervaardigd en op welke wijze en door wie het is gebruikt.

July 2020,

Anneke Hoekstra (10454780)

In the interdisciplinary MA thesis project at the University of Amsterdam ‘Writing the Biography of

a Notebook: interpreting a richly decorated baroque notebook from the collection of the Rijksmuseum Amsterdam’, the object BK-17172 is the primary source. The object’s ‘life cycle’ is

investigated, to determine how, where and when it was manufactured and in what manner and by whom it was used.

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Figure 1a, b, c. From left to right: front, inside, and back of the notebook.

Anonymous, Notebook of tortoise, with decorations of gold, enamel and gemstones. In the closing a pencil,

decorated with an enamelled bust, Rijksmuseum Amsterdam, Amsterdam (BK-17172), ca. 1710-1730,

Dresden, Tortoise, gold, enamel and gemstones, h. 10.8cm x w. 6.4cm x d. 1.5cm. Credit: photography by Rijksmuseum Amsterdam.

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2.2 Metal ... 23 2.2.1 Book fittings ... 23 2.2.2 Stylus ... 31 2.2.3 Settings ... 33 2.2.4 Conclusion ... 34 2.3 Enamel ... 36 2.3.1 Technique: basse-taille ... 36 2.3.2 Enamel composition ... 37 2.3.3 Conclusion ... 41 2.4 Gemstones ... 43 2.4.1 Preliminary characterisation... 44 2.4.2 Enhancements ... 49 2.4.3 Conclusion ... 50 2.5 Conclusion ... 52

3. Style and Iconography ... 53

3.1 Book fittings ... 53

3.2 Iconography ... 54

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3.4 Conclusion ... 58

4. The content: owner, function, and use ... 61

4.1 Content ... 61

4.1.1 Content description ... 61

4.1.2 Languages and scripts ... 61

4.1.3 Names ... 62

4.2 The owner ... 63

4.2.1 Upbringing and education of Anna Petrovna... 63

4.2.2 Anna Petrovna and Karl Friedrich of Holstein-Gottorp... 64

4.3 Function and use ... 66

4.3.1 Souvenir d’amitie? Carnet de bal? Album amicorum? ... 66

4.3.2 When was it used? ... 71

4.4 Conclusion ... 71

Conclusion ... 73

Further research ... 75

Bibliography ... 76

Summary ... 86

Appendix I. Technical information... 87

Appendix II. XRF Measurements... 88

Appendix III. Wax patterns for the notebook’s figures? ... 102

Appendix IV. Photographs content notebook ... 104

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Acknowledgements

I would like to express my gratitude and appreciation to the many people who contributed to this thesis, by assisting and supporting me throughout the process.

Thank you to my supervisor, prof. dr. Erma Hermens (RMA/UvA), for contacting the Rijksmuseum Amsterdam, and arranging the wonderful subject of this thesis. For providing guidance and honest feedback, but also for showing your trust in me and my research and for your gentle words of encouragement, which kept me positive during this journey.

I am indebted to the Rijksmuseum Amsterdam for trusting me with an art object from their collection. I would like to thank the Metal Conservation Studio, for keeping the notebook and for letting me use their facilities. Special thanks goes out to Suzanne van Leeuwen (RMA), who not only served as the contact person, but also helped me operate the digital camera, had the UV-photos taken, shared valuable information, and gave very helpful suggestions for interpreting data of the technical analyses.

For the technical examination I wish to thank dr. Luc Megens (RCE) for the initial contact and for deciding on the techniques. Dr. Han Neevel (RCE) and prof. dr. Arie Wallert (RMA/UvA) carried out the XRF measurements and helped interpreting them, for which I am very thankful.

For taking the time and effort to translate the pre-revolution Russian texts, I wish to pay my regards to prof. dr. Jos Schaeken (LU) and to my friend’s mother Marina, without whom I would never have known the nature of the language and the content of the texts.

I would further like to thank prof. dr. Maarten van Bommel (UvA), prof. dr. Ella Hendriks (UvA), dr. René Peschar (UvA) and dr. Maartje Stols-Witlox (UvA), as well as dr. Abbie Vandivere (Mauritshuis/UvA), dr. Arjan de Koomen (UvA), and dr. Tonny Beentjes (UvA) for their advice and suggestions during this research, but also for forming me academically during the master’s program.

Finally, I am grateful to my fellow students Suzanne Bul (UvA), Jan van Daal (UvA), Marélise Pollard (UvA), Fahed Ibrahim (UvA), Laurens van Giersbergen (UvA), Timothy Greening (UvA) and Karina Foppele (UvA), to my parents, Kees Hoekstra and Adri Bunte, and to my sister, Maartje Hoekstra, who were always available to critically assess my writing, by giving advice on the content or linguistics, or help me out in another way, and who were there for moral support.

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Glossary

Book fittings Metal attachments to book bindings, to decorate and/or protect them from wear and damage. Other terms are ‘book fixtures’ and ‘book furniture’. Centre piece Book fitting in the centre of the cover

Corner piece Book fitting on the corner of the binding.

Fore edge The front outer edge of a book, opposite the bound edge (spine). Head The top edge of a book

Headcap Book fitting on the spine’s head and tail Spine The bound edge of a book

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Introduction

The Rijksmuseum Amsterdam holds a varied collection of artefacts. Part of this collection has been subjected to extensive (art) historical and technical research. Rembrandt’s famous militia portrait the Night Watch (1642), for example, is being examined thoroughly at this very moment (Rijksmuseum Amsterdam, n.d.). A part of the collection, however, has received little attention thus far. One such object, a small notebook, was kindly provided by the Fine and Decorative Arts Department of the Rijksmuseum Amsterdam for extensive object-based research. The notebook is currently dated ca. 1710 – ca. 1730, it has no attribution, but is believed to originate from Dresden.

Object description

The object at stake is a small notebook, measuring 10.8x6.4 cm (fig. 1a-c). The cover is supposedly made of tortoise and is richly decorated with an extensive amount of golden coloured book fittings, enamel, and apparent gemstones. A golden coloured metal stylus, decorated with an enamelled bust and colourless gemstones, simultaneously serves as a closing, when pushed through six rings at the fore edge of the booklet (fig. 2).

The book fittings are partly attached by little pins through the cover and partly by folding over the cover (fig. 3). Some are merely decorative; others serve a functional purpose too. Parts of the book fittings and all the metal stone settings are discoloured and turned dark-grey. The enamel comes in the colours green, light blue/turquoise, dark blue, black, and white, of which only the last colour is opaque. The translucent enamels reveal small grooves in the underlying metal (fig. 4). The notebook is adorned with a total of 115 stones – one stone at the spine is missing – coloured pink, blue, green, and colourless. The stones are translucent and differ in size and cut. The covers are lined with a finely woven, shiny, green fabric.

Both front and back cover have a figurative centre piece. The front depicts a figure, seemingly dancing and playing a tambourine. The back figure is holding up a glass with one hand, while carrying a flask in the other. Its left leg is turned inwards, in an unnatural position. Both are standing on a decoration of two mask-like faces, under a chandelier.

The notebook’s 24 pages are bound by means of two metal nails through the head and tail at the spine. The nails are held by four metal ringlets going through all pages (fig. 5). The first and last page, consisting of the same sheet of paper, show golden coloured floral decorations on a turquoise ground, with (partial) birds and a rabbit. They are slightly thicker than the other pages, which reveal inscriptions written in multiple languages and handwritings.

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Figure 2. Side of the notebook, showing how the stylus

serves as a closing. Credit: photography by Rijksmuseum Amsterdam.

Figure 3. The book fittings are mounted on the cover by

pins, indicated by the red circles (drawn by Anneke Hoekstra), and by folding over the cover. Credit: photography by Anneke Hoekstra and Suzanne van Leeuwen on 28-03-2019.

Figure 4. Detail of figure 1a. showing tarnishing of the book

fittings; discolouration of the stone settings; and small grooves in the enamel’s underlying metal.

Figure 5. The inside of the notebook, showing how the book

was bound by means of metal pins running over the length of the paper in the middle of the book; and written

inscriptions. Credit: photography by Anneke Hoekstra and Suzanne van Leeuwen on 28-03-2019.

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Aim and Research question

The notebook is composed of various seemingly expensive materials, of which some are known to have a long history of imitation – especially from the Scientific Revolution onwards, which is substantiated by the many books of secrets (books of techniques) that were handed down from that period (Smith 2004; The Making and Knowing Project, 2020). The inside of the notebook shows several inscriptions. This research will be two-fold: on the one hand is the notebook as an art object and a material ‘thing’ made by one or more artisans; on the other hand the function and use of the notebook, representing two very different, but significant moments in the ‘life’ of the object. Reflecting on these moments will reveal information on the artisanal and cultural past of the period in which the object was made and used. Research that has been conducted thus far is very minimal and outdated (section 1. Previous research). Previous studies were written in pre-revolution Russian and in Dutch, languages that are not universally understood (Benois and Prakhov 1902; De Foelkersam 1913; Holzhausen 1960). The aim of this research is to gain as much information as possible from the object itself, from similar objects and from relevant literature, to form a more complete picture of the object’s biography. The research adds to the current state of knowledge by reconsidering the previous findings, and by adding technical, historical, and cultural research. The main research question is formulated as follows: how can an interdisciplinary study of the manufacture, function, and history of the notebook BK-17172 in the collection of the Rijksmuseum Amsterdam support its interpretation?

Structure and Methodology

To answer this question, the research is divided in four chapters. The first chapter gives a short overview of the research that has previously been conducted, presenting the current state of knowledge on the provenance, date, function, and attribution of the object.

Chapter two focuses on ‘the making’ of the notebook in four subchapters. By combining non-invasive scientific analysis, material history and art technological source research, it answers which materials and techniques were used in the manufacturing of the cover of the notebook. Are they real or (cheaper) imitations? The chapter also reflects on the historical occurrence and use of these materials and techniques, to provide a first indication regarding dating. The chapter is built up the same way as the booklet: the first subchapter treats the coverboard material. The second subchapter deals with the metal components: the book fittings, they stylus, and the gemstone settings. The third subchapter handles the enamel, and the fourth subchapter the gemstones. The analytical methods employed are digital microscopy, ultraviolet (UV) photography, using longwave UV radiation (365nm), and X-ray fluorescence (XRF). An explanation of the analytical methods and equipment descriptions can be found in Appendix I.

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Chapter three follows up on this chapter, by studying the style and iconography of the separate elements of the notebook. By exploring when the stylistic and iconographic features were in vogue, and by comparing them to other artworks, the rough dating from the previous chapter is narrowed down, and a very cautious attribution is proposed.

By carefully investigating the content of the notebook, and by comparing the booklet to similar, contemporary objects, the last chapter gives answers to the questions: who was the owner of the notebook, how did it function, and when was it used?

Relevance for Technical Art History

Because of the diversity of the materials and because relatively little research has been performed on the object, this mixed media notebook lends perfectly for object-based research by a technical art historian. In object-based research the physical artwork or artefact is the primary source that generates the initial research questions. By studying the materials and techniques that were used, information on the working methods of the artisans is gained. But the research does not stop there. Just as interesting is to understand why these materials and techniques were used. As products of the historical period they were made in, the objects convey information about this period and its society. Technical Art History therefore not only gathers technical information, but also reflects on this information to understand more about the history of the object and the historical period it was made in (Hermens 2019). In the specific case of this thesis, the textual inscriptions – although cryptic and incomplete – that the notebook contains, give an extra dimension to the historical factor, because they are such clear traces of use and ownership.

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1. Previous research

1.1 Provenance, function, date, and attribution

The notebook’s provenance extends back to 1901, when it is listed in Baron G. Lieven’s collection catalogue of the Hermitage St. Petersburg. It was on display in the ‘Gallerie der Kostbarkeiten’, the Department of Precious Objects, which was composed of works of art and rarities from former imperial holdings, such as the Kunstkammer of Peter the Great, the Old Hermitage, the Winter Palace, and the Orusheinaja Palace. The collection gradually expanded with later purchases and donations, imperial as well as private (Lieven 1901, 60, 95).1

In 1902 the notebook is depicted and described in Les Trésors d’Art en Russie

(Khudozhestvennye sokrovishcha Rossii), a Russian, monthly-running publication (Benois and

Prakhov 1902, 309-10)(fig. 6).2_{In the entry the inscriptions are mentioned and investigated for} the first time. Where possible, the inscriptions were transcribed, but several were considered illegible. The content of the notes makes the authors believe that the booklet once belonged to crown princess Anna Petrovna (1708-1728), the eldest daughter of the Russian tsar Peter I and Catherina I. It is further stated that the notes are partially written by her, and partially written by her fiancé, Karl Friedrich (1700-1739), duke of Holstein Gottorp (Benois and Prakhov 1902, 309; Jos Schaeken, Personal communication, May 8, 2019).

Around a decade later, the notebook is presented in a second monthly-running magazine:

Bygone years (Starye Gody), by the art historian Armin de Foelkersam (1913, 17-8) (fig. 7).3_He describes the figures on the front and back cover as harlequins from the Italian commedia dell’arte, and typifies the bust on the accompanying stylus as a moor or Arab. The article contains a more complete transcription of the notebook’s inscriptions than the entry in Les Trésors, and it is of better quality, according to Jos Schaeken, professor of Slavic and Baltic Languages at Leiden University (Personal communication, May 8, 2019). De Foelkersam cautiously assigns some inscriptions to Anna Petrovna. Based on the cover’s stylistic features, which he thinks fit a late seventeenth century dating, it is suggested that the notebook might have been in the possession of Karl Friedrich’s parents first, but was not used until after the marriage of Anna Petrovna and

1_{According to the catalogue’s foreword, Lieven – curator at the Hermitage St. Petersburg – was the first to}

catalogue the museum’s collection.

2_{Russian title: Художественныя сокровища Россіи. The magazine ran from 1901 to 1907. The purpose of the}

publication was to describe the most important artworks found in Russia, both ancient and modern, foreign and Russian, held in museums as well as private collections. For more information on the publication, see Johnson 2006, 52-64.

3_{Russian title: Старые годы. The magazine ran from 1907 to 1916 and pursued a similar agenda towards art}

and culture as Les Trésors d’Art en Russie, which had declined due to financial difficulties. For more information see Johnson 2006, 62-71. De Foelkersam is also known as Von Foelkersam or Von Fölkersahm.

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Karl Friedrich. De Foelkersam states that people could secretly exchange their thoughts amid others in these notebooks. A lady, for instance, could tell something to her female friend, or her love interest. According to De Foelkersam such notebooks were in fashion at the end of the seventeenth century until the second half of the eighteenth century, after which the “Souvenir

d’amitié” became fashionable. He describes how it can be difficult to decipher such texts and their

authors, because the questions and/or answers are often partly verbal and partly written down, and often there is a lack of names as a result. Sometimes however, he adds, one finds simple poetry and aphorisms in such booklets.

The next source featuring the notebook is the inventory of Fritz Mannheimer’s collection of ca. 3000 objects, drawn up by the art historian Otto von Falke in 1935-36, after Mannheimer’s great bank debt had reached the surface (1936, 82). In the late 1920s and the early 1930s, the Soviet authorities undertook the export of museum collections, as a solution to its political and economic problems (Solomakha 2009, 111-2). Between 1927-1933 fine art and applied art objects were sold abroad to fund the industrialisation and agriculture, under the slogan “Art for Tractors” (Kaldenbach 2014a, 2). Presumably at some point in this period, Fritz Mannheimer (1890-1939), a German banker and avid art collector, acquired the notebook through art dealers and intermediaries (see Kaldenbach 2014a for an extensive study on the formation of Mannheimer’s collection). The exact channels through which the notebook entered the Mannheimer Collection are unknown. As director of ‘Mendelssohn & Co. Amsterdam’ – a subsidiary company of ‘Mendelssohn & Co. Berlin’, one of the leading private banks at that time – Mannheimer had moved into the home office at Hobbemastraat 20 in 1920, opposite the Rijksmuseum Amsterdam, where he housed his enormous and diverse collection of art and curiosities. The interior, although of very high quality, did not exactly meet the Dutch sober taste, Figure 6. The notebook featured in the magazine Les

Trésors d’art en Russie. Credit: Benois and Prakhov

1902, plate VI.

Figure 7. The notebook featured in the

magazine Starye Gody. Credit: De Foelkersam 1913, after page 12.

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and soon the house was nicknamed ‘Villa Protski’, referring to the Dutch word ‘protserig’, meaning ‘showy’ (Haga 1974, 87-90; Kaldenbach 2014b, 6; Van der Ham 2000, 281).

For the art purchases Mannheimer used the bank’s money, which put him into great debt. In 1934 his partners forced him to an unusual and complicated legal deal: his art collection was sold for over 6.5 million guilders to The Artistic & General Securities Ltd, a company founded for this purpose by Mendelssohn & Co. The Artistic leased the collection back to Mannheimer, which is how the collection remained at the Villa. Although contractually forbidden, Mannheimer continued to buy art at the bank’s expense. Soon his debt was driven back up to its previous level and exceeded 13 million guilders by the time of his death (Jonker 2013; Haga 1974, 87-8; Van Leeuwen, Van Bennekom, and Creange 2014, 274-5; Kaldenbach 2014b, 5). The already financially struggling Mendelssohn & Co. Amsterdam went bankrupt and had to close its doors three days after Mannheimer’s death (Jonker 2013). The Deutsche Reichsbank became the full legal owner of the majority of the collection, which initially remained at the Hobbemastraat. As soon as The Netherlands were occupied in 1940, the collection spiked the interest of Herman Goering and Adolf Hitler. On behalf of the Reichskommissariat a complete inventory of the collection – including the notebook – was made by Kajetan Mühlmann, for which he relied heavily on Von Falke’s inventory (Kieslinger and Mühlmann 1941, 65; Van der Ham 2000, 281; Kaldenbach 2014b, 7,9). In 1941 Hitler bought the collection. The majority was moved to Linz to fill Hitler’s future

Führermuseum. The museum, however, was never build, and a large part of the Mannheimer

Collection was found in a salt mine in Austria (Van Leeuwen, Van Bennekom, and Creange 2014, 276; Kaldenbach 2014b, 12). Via several instances the collection finally passed through the Dienst

voor ‘s Rijks Verspreide Kunstvoorwerpen (DRVK – National Service for State-Owned Works of Art)

and were lent to the Rijksmuseum in 1952. In 1960 this loan was converted into a gift (Van der Ham 2000, 281; Haga 1974, 88-90).

The same year two half pages were devoted to the booklet in the article De Dresdense barok

in het Rijksmuseum, by the German art historian Walter Holzhausen (1960, 12-3). He quotes Les Trésors d’art en Russie as a source, but it is unclear which exact parts of his article are derived from

the magazine. De Foelkersam is not cited at all. Holzhausen’s research is a comparative study to other art objects. Possibly he performed visual analysis too, but he does not specifically say so. According to Holzhausen the booklet functioned as a carnet de bal, a dance card, and contains a “met onvast potlood gekrabbelde kleine roman” (short novel scribbled with unsteady pencil), existing of alternating Russian (partly Old Slavic) and German (partly Lower Saxon) notes. He states that the notes are written by several men and women, with disguised names, but that, according to the description in Les Trésors, the Russian verses were composed by Anna Petrovna and her fiancé, the duke of Holstein. Holzhausen wonders if the notes were made in the course of a dance event, perhaps at the court of August the Great.

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Table 1 presents a compilation of the publications in which the notebook has appeared, and provides an overview of previous material identification, dating and attribution. According to the sources the notebook’s cover consists of the precious materials tortoiseshell, gold, enamel and gemstones. The country in which the notebook is manufactured is believed to be Germany, except for De Foelkersam, who considers it to be an Italian piece. Holzhausen is very much convinced that the notebook is made in Dresden, possibly by one of the court jewellers of August the Strong, Johann Christoph [sic] Köhler – by which he must mean Johann Heinrich Köhler (1669-1736), court jeweller from 1718 – or Johann Melchior Dinglinger (1664-1731), court jeweller from 1698.4 He therefore dates the notebook in the eighteenth century. Details that in Holzhausen’s opinion point to the art of goldsmithing in Dresden are: diamonds set in silver, the engraving on the golden mounts, the head of a Turk on the pencil [sic], and the green and blue enamel, which he calls typical for Köhler. He further argues that the harlequins remind of the “Italiaanse Comedie” (Italian Comedy), that saw its glory days in Dresden at that time. Lieven and De Foelkersam date the notebook at the end of the seventeenth century, and in Les Trésors it is dated around the turn of the century (Lieven 1901, 95; Benois and Prakhov 1902, 309; De Foelkersam 1913, 17-8; Von Falke 1936, 82; Kieslinger and Mühlmann 1941, 65; Holzhausen 1960, 12).

1.2 Technical examination

The Rijksmuseum Amsterdam neither holds a restoration report of the notebook, nor has the notebook been subjected to technical examination before. It is worth to mention that the notebook shows no signs of restorations or repairs in UV-light, apart from the tiniest dot on the front of the notebook, on the right side near the second ornament from above (fig. 8).

4_{Johann Christoph Köhler was a brother of Johann Heinrich Köhler. He was also trained as a goldsmith, but}

pursued another, unknown, profession (Syndram and Weinhold 2019, 14).

Figure 8. Detail of figure 11.

showing a filling in the

notebook’s cover. Credit: image by Anneke Hoekstra.

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Table 1. Overview of publications in which the notebook has been described or researched, presenting previous material identification, dating and attribution.

Source Object

description and function

Listed

materials Date Attribution

Lieven 1901 (collection catalogue)

Taschenbuch

(pocketbook) Tortoiseshell, gold, enamel Second half 17 th

century Germany

Benois and

Prakhov 1902 Notebook Tortoiseshell, gold, enamel, gemstones, green silk End 17th _/ beginning 18th century Germany Foelkersam 1913 Notebook, forerunner of a Souvenir d’amitié Tortoiseshell, gold, white, green, and blue enamel, 79 diamonds, 7 emeralds, 10 rubies, and 4 sapphires

End 17th_{century Italy}

Von Falke 1936 (inventory) Notebook Tortoiseshell, gold, enamelled gold, rubies, emeralds, and diamonds 17th_century _Germany Kieslinger and Mühlmann 1941 (inventory) Notebook Tortoiseshell, gold, enamel, rubies, emeralds, and diamonds Around 1700 Germany Holzhausen

1960 Notebook, carnet de bal

(dance card) Tortoiseshell, enamelled gold, gemstones, diamonds 18th_century _Dresden, possibly Johann Christoph [sic] Köhler or Johann Melchior Dinglinger

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2. The Making: manufacture, materials, and techniques

The earlier sources in which the booklet is discussed, identified the different materials that are used for the cover as tortoise, gold, enamel, and gemstones (see table 1). All incredibly expensive and valuable materials, which are known to have been imitated in the past. Although the characterization of these materials could be correct, it is unclear how these sources came to the determinations. The following chapter will identify the materials and techniques used in the notebook’s fabrication by visual and scientific analysis, to understand how the notebook was made. By reflecting on the historical use of the materials and manufacturing methods, this chapter will indicate the object’s material value, and provide first indications regarding its dating.

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2.1 Tortoiseshell

The cover of the notebook consists of three separate parts, connected by metal hinges: the front cover, the back cover, and the spine. The colour is predominantly a matte dark chocolate brown, variegated with irregular caramel-coloured patches. At first glance the surface looks smooth. In magnification, tiny scratches and dents become apparent. Several spots show traces of wear and use (fig. 9,10). Swirling lines are visible over the whole surface. In UV-light, this pattern of swirling lines becomes especially clear as brownish lines on a fluorescent blue-white background (fig. 11a,b). This blue-white UV fluorescence, combined with the colour and visual appearance of the material, is characteristic for tortoiseshell, and sets it apart from imitations (Hainschwang and Leggio 2006, 40-5; Frazier and Ishihara-Brito 2012, 832).5_{The swirling lines most likely} correspond to the keratin formation that occurs as the turtle grows. Keratin – the principal chemical constituent of tortoiseshell – is a protein complex, that gets secreted by the epidermis (the outer skin). The cells die and keratinize. This is a repeating process, which is why the keratin layer gets build up from the base (bone). Through continuous growth, different layers and growth lines get formed (Day 2015; Rijkelijkhuizen 2008, 74; Ward 2008, 714).

5_{Horn has been used to imitate tortoiseshell as well, and, because it consists of keratin too, also fluoresces in}

UV light. The swirling lines, however, indicate that it is tortoise. Figure 9. Detail figure 1c. showing scratches

and dents in the upper right corner of the tortoiseshell back cover.

Figure 10. Detail figure 1c. showing wear in

the lower left corner of the tortoiseshell back cover.

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Figure 11a,b. Longwave (365 nm) UV photographs of the notebook. Credit: photography by Rijksmuseum

Amsterdam.

2.1.1 Tortoiseshell as an artist’s material

Other than the name suggests, tortoiseshell does not actually come from tortoises, which are land-based reptiles, but from sea turtles. The tortoiseshell that is most commonly used in artefacts, was harvested from the hawksbill turtle (Eretmochelys imbricata) and, less frequently, the green turtle

(Chelonia mydas) (fig. 12). The first is the smallest of the two species but has a thicker shell (max. 9-12 mm). Both species display the characteristic pattern and can therefore not be distinguished by the naked eye, especially after being worked (Hainschwang 2006, 36-8; Rijkelijkhuizen 2010, 97; Chaiklin 2016, 219; Williams 2002, 33). The hawksbill turtle is found in the Atlantic, Pacific, and Indian Ocean. The green turtle is found worldwide in the tropical and subtropical seas, the Atlantic, Pacific, and Indian ocean, and the Mediterranean and Black sea.

The turtle shell is a complex shield, covering and protecting the rest of the animal’s body, and is comprised of over 50 dermal bones. The shell is composed of two main parts, the carapace (dorsal part) and the plastron (ventral part), which are connected by lateral bridges along the midflanks. The outer epidermal layer of these parts is made of keratinous scales, also called ‘scutes’ or plates (fig. 13). As an artist’s material, the term tortoiseshell refers to these scutes, after

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they are processed. The carapace of the hawksbill turtle has thirteen main plates, displaying the characteristic multi-coloured marbling pattern, ranging from black to brown-red, to orange and yellow. The scutes overlap each other like tiles on a roof. Their size can grow up to 17cm wide and 30cm long, and they are 1.5 to 3.5 mm thick. The plastron scutes are white to yellow, with occasional dark pigmentation, and is commonly referred to as ‘blonde tortoiseshell’ (Wyneken, Godfroy and Bels 2007, 1-2; Rijkelijkhuizen 2010, 97-8; Hainschwang and Leggio 2006, 36).

In the West, tortoiseshell was used in antiquity in Egypt, Greece, and Rome. At the end of the fifteenth century commercial exploitation of the material began in Portugal and Spain, because of overseas exploration and trade (Hainschwang and Leggio 2006, 36; Saviello 2018, 116) (fig. 14). In the seventeenth and eighteenth centuries, the material was used throughout Europe for veneers on furniture and musical instruments, for inlays of Boulle marquetry, and for various luxury items such as snuff boxes, combs and fans (Shenton 1992, 175; Rijkelijkhuizen 2010, 101) (fig. 15,16). Next to gold, silver, and gemstones, it was one of the most valuable materials in the applied arts. The luxury items made of the exotic material were therefore only found in the richest households (Rijkelijkhuizen 2010, 105; Beentjes and Veenemans, n.d., 135). The fact that tortoiseshell has been imitated in different manners and materials (e.g. painting, horn and more recently plastic), shows the popularity that the material still has.

Figure 13. Cross-section of carapace and plastron with

external keratinous scutes over internal bony elements of a hawksbill sea turtle. Credit: Frazier and Ishihara-Brito 2012, 828.

Figure 12. Hawksbill turtle (Eretmochelys

imbricata), Museu de ciències naturals de Barcelona, Barcelona (MZB 99-1391). Credit: Museu de ciències naturals de Barcelona,

https://zoologiaenlinia.museuciencies.cat /detall/zoologia_cordats/N883972/?lang =en.

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2.1.2 Harvesting, properties, and workability

To harvest tortoiseshell the scutes get removed from the bony shell by means of heat, either by holding it over a fire, or by boiling it in water (Rijkelijkhuizen 2010, 98). Because the animal is an endangered species, harvesting and trading in tortoiseshell is prohibited today. Tortoiseshell is semi-transparent or translucent. When the material is polished, it receives a lustrous shine. Due to this property, it was often used in combination with precious metals or mother of pearl (Ward 2008, 714; Shenton 1992, 175). Like other keratinous tissues, tortoiseshell is a thermoplastic. As raw material it is hard, brittle, and rigid, easily sawn and worked with basic tools. However, when it gets heated – by steam, by boiling it in salted water, or by applying direct heat – it can be softened and made pliable. In this softened state, it can be bent, shaped, or impressed. When it cools back to room temperature it will retain its new shape or form. Sheets of tortoiseshell can also be welded together to form larger sheets (Ward 2008, 714-5; Rijkelijkhuizen 2010, 98).

2.1.3 Tortoiseshell as bookbinding material

About the use of tortoiseshell as a bookbinding material, little is known thus far. The characteristic handling properties of tortoiseshell are actually the opposite of what is required for bookbindings. It is stiff, brittle and inflexible, and to be able to open the book, it will always consist of at least three parts: the upper board, the lower board and the spine piece (either flat or rounded), which are attached to each other with hinges. For this reason, Rijkelijkhuizen argues that a tortoiseshell binding was merely decorative. According to a survey by Shenton of about forty bindings, tortoiseshell was used for bookbindings from the middle of the seventeenth until the middle of the eighteenth century, with a brief nineteenth century reappearance, which is supported by two studies on book fittings of Bernard van Noordwijk (2006; 2013). It was mainly used in The Netherlands, France, and England, and primarily as a luxury cover material for religious texts. The bindings usually have book fittings to protect the brittle tortoiseshell. They were generally executed to a high standard, often in gold, silver, or brass, and contribute to the prestigious look. Tortoiseshell bindings can also display decorations hot-pressed into the shell (Rijkelijkhuizen 2010, 103-4; Shenton 1992, 174-7).

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Figure 14. Anonymous, Hunting sea turtles, Rijksmuseum Amsterdam, Amsterdam (RP-P-2007-727),

1612-1652, Amsterdam, print, h. 52mm x b. 158 mm. Credit: Rijksmuseum Amsterdam, http://hdl.handle.net/10934/RM0001.COLLECT.452794.

Figure 16. Anonymous, Fan, Victoria and Albert Museum,

London (M.265-1960), 18th_{century, Naples(?), inlaid} tortoiseshell, gold and animal skin. Credit: Victoria and Albert Museum,

http://collections.vam.ac.uk/item/O92095/fan-unknown/.

Figure 15. Anonymous, Letter case and

comb, Rijksmuseum Amsterdam,

Amsterdam (SK-C-1216), ca. 1600- ca. 1700, textile and tortoise. Credit: Rijksmuseum Amsterdam,

http://hdl.handle.net/10934/RM0001.COL LECT.11744

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2.2 Metal

The metal components of the notebook are divided in three subgroups: the book fittings, the accompanying stylus, and the gemstone settings. XRF was performed to identify the metal composition. To understand more about the manufacture and craftsmanship’s methods, toolmarks on the metal were studied with digital microscopy.

2.2.1 Book fittings

The book fittings are of a bright, yellow-golden colour. Keeping in mind that the booklet has not been cleaned for at least several decades – if ever – the metal appears to be in good condition, suggesting a high gold content. There are, however, several areas where the metal is tarnished and turned dull, dark grey. The tarnished areas seem to be divided randomly over the surface of the booklet, both front and back (fig. 17).

2.2.1.1 XRF measurements

XRF measurements were taken on the front cover, on four spots: on an untarnished area in the centre of the chandelier; on a tarnished area in the large, central fitting at the top; and on the arm and the chin of the front central figure (fig. 18).The measurements show that the metal is an alloy of mainly gold (Au), some copper (Cu), and a very small amount of silver (Ag) (see Appendix II, no. 6-9). The four spectra are fairly similar. Interesting differences to point out are the somewhat higher peak for silver in the tarnished spot, compared to the other three spectra. The spectrum of the figure’s arm shows a considerably lower peak for gold than the other three spectra, while some calcium (Ca) and iron (Fe) were detected. The peak for copper is slightly lower in the spectrum of the figure’s chin compared to the other three spectra.

Gold is a precious metal. In its pure form it does not react with oxygen, and as such it is resistant to corrosion. However, pure gold is – next to being rare and expensive – also extremely soft. To harden the metal and make it less prone to deformation, it is mixed with other metals (Ward 2008, 255.). An alloy of gold, copper and silver was used often, for both aesthetic and technical reasons, since the gold keeps most of its colour, lustre, and malleability. While alloying gold with only copper has minimal effect on the working properties, it makes it more liable to cracking, and therefore alloys of gold, copper and silver were preferred (Ogden 1999, 23). Over time such alloys tend to exhibit thin films of surface corrosion by reacting with oxygen or sulphur in the atmosphere (Scott 1983, 194-5). Because sulphur is a light element (Z=16), it was not detected.6_{However, copper and silver sulphides are both dark-grey and a small percentage can}

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already cause discolouration (Afonso et al. 2009, 1763). The tarnishing may be a combination of the two. The slightly higher peak for silver in the tarnished area supports the suggestion of silver corrosion.7

The lower peak for gold in the spectrum of the figure’s arm, and the lower peak for copper in the spectrum of the figure’s chin are most probably the result of inhomogeneous element distribution. More interesting is the detection of calcium and iron in the spectrum of the figure’s arm. As opposed to the other measured spots, the arm has a course texture. Most likely, powdered iron scales and levigated chalk were used as mild abrasives for the final polishing of the gold and got trapped in the textured surface of the arm (Gettens, Fitzhugh and Feller 1974, 160; Rivers and Umney 2003, 450-3, 639). Polishing a small, silver chalice with chalk is described by the Benedictine monk Theophilus Presbyter (ca. 1070-1125) for example: “Then take a burnisher, rub it on a flat smooth hone and then on a piece of oakwood covered with ground charcoal, and with it burnish the bowl […]. Then rub the work with a cloth and finely scraped chalk until it is shining bright all over” (1963, 102). The final step for making medals in Benvenuto Cellini’s (1500-1571) treatise on goldsmithing is to “polish it up with powdered iron scale just as you did before with the coins” (1898, 74). The translator of the treatise, Ashbee, draws a parallel to today’s jewellers

rouge, which is a very fine, powdered iron oxide, used to put the final polish to precious metals for

a lustrous finish (1898, 74, note 3).

7_{For this research, an indication of the metal composition was strived for. For a more accurate result, analysis}

should be undertaken on multiple spots.

Figure 17. Tarnish spots on the book fittings. Credit: photography by

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2.2.1.2 Manufacture and toolmarks

Gold with a relatively high purity does not cast well: it flows poorly in the mould, it shrinks during casting and thus produces poor definitions (Ogden 1999, 7). In magnification, tiny pinpricks are visible on the bust of the stylus (fig. 19). They are caused by minute gas bubbles and are a sign of porosity, a characteristic of casting (Ogden 1999, 8). The central figures do not display such clear characteristics of casting. The half-relief and the fine details on the faces, hands, and feet, however, suggest that they were cast too (fig. 20).

There are various ways to cast metal. Cire-perdu, or lost-wax casting – an ancient method which has its origin in the Chalcolithic period before 4000 BC – was the preferred method for bronze sculpture casting in the Renaissance and Baroque (Davey 2009, 152; Beentjes 2019, 9). Smaller, low relief items, such as seals, medals, plaquettes and furniture mounts, were more frequently made by mould casting. Shaped moulds could be manufactured from for example stone, clay and metal (La Niece 2016, 264; Smith 2016, 220). Gold and silver can also be cast in cuttlefish bone. A very elaborate instruction on making a cuttlebone mould for a medal is given in BnF Ms. Fr. 640, a late sixteenth century book of secrets (book of techniques), which concentrates for the Figure 18. Indicating where the XRF Measurements were taken. Credit: Anneke

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largest part on techniques of mould making, metal casting and colour-making (Smith 2016, 214). According to the anonymous author of the manuscript “Gold & Silver are able to cast well there, but it never comes out very neat”. The author further warns that the bone must be dry, especially for gold “which does not want humidity”, but that the bone will be brittle and flake when too dry. The bones are dry enough when they “cry & crackle once brought near the ear”. The instructions tell to press the medal into the soft side of the bone “which does not have any half circles”, after smoothening and flattening the bone on “some smooth wood” (Making and Knowing Project 2020, fol. 145r-v). In his Weg-wyzer voor Aankomende Goud en Zilversmeeden, first published in 1721 in Amsterdam, Willem van Laer gives a comparable description for casting in “Visbeen” (literally: “fishbone”), which was done in “voorige tyden (en ook nog wel)” (“in earlier times, and still”), if something did not needed to be cast “scharp” (“sharp”). He adds that the visbeen is retrieved “aan

de oevers der Zee” (“from the sea banks”) and can be bought at paint sellers or at sellers of

silversmithing tools (Van Laer 1721, 142-3).

Both sources agree, however, that for gold the popular method of sand mould casting is preferred over cuttlebone mould casting, since it gives sharper definitions (Making and knowing 2020, fol. 145v; Van Laer 1721, 142).8_{Sand mould casting had several other advantages over lost} wax casting and other types of mould casting. The method is fast and cost-effective – because sand is readily available and can be re-used – and less labour intensive and fragile compared to other moulds, like stone or clay. In addition, as opposed to lost-wax casting, the models could be re-used (Beentjes 2019, 69, 76-7). According to Beentjes, the first use of sand as a mould material in Western Europe probably dates from the late fourteenth century. Most of the early textual references to sand mould casting cover the use of the technique by gold- and silversmiths and medal founders (Beentjes 2019, 48-52).9

In the sand mould casting technique, a pattern (model) made from wood, metal, or another sturdy material, is pressed into the sand, which is contained by a frame. Two-part mould frames (bi-valve flasks) were used when the pattern had relief on both sides, such as medals (fig. 21). The figures on the notebook have a flat backside. Such items, with a design on one side, could also be cast in a so-called open sand mould, which is basically a box of sand. About the materials of patterns, much has yet to be uncovered. 10 _{They are intermediary objects used in the} manufacturing of art works, which are usually not transferred to the present. Thus, even though

8_{For recipes and instructions in these manuscripts on sand mould casting, including recipes for sand, see: Van}

Laer 1721, 130-142; and Making and Knowing Project 2020, fols. 15r, 118v-120r. See: Carlson and Katz 2020, for a dissection of the recipe on fol. 118 and a comparison to contemporary recipes.

9_{For a more elaborate overview on the history, development and technology of sand mould casting in Europe,}

and an excellent account on the different types of moulding sand that were used throughout the centuries and where to find the recipes see: Beentjes 2019, 19-79.

10_{See Landsman and Rowen 2020, for a research into the procedures of making original patterns for casting,}

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one might want to reuse a pattern, they are ephemeral. Therefore, one must look at artworks and/or recipes for clues on their materials. The texture of the figure’s arm is best explained by a wax pattern (fig. 22). See Appendix III for a short discussion on the use of wax patterns.

Figure 19. Showing pinpricks in the bust of the stylus,

indicating casting. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

Figure 20. Detail fig 1a,b. the half-relief

and fine details suggest casting of the figures.

Figure 22. Detail showing the texture of the arm of the

back figure and engraving. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

Figure 21. A bi-valve flask used for sand

casting, and a cross-section through the mould. Credit: Farmer 1994.

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From the toolmarks on the other book fittings one can tell that they are not cast but cut out of flat sheet gold (fig. 23). The goldsmith’s craft is a very conservative one. Some technological advances aside, the industry remained much the same until the First Industrial Revolution in the second half of the eighteenth century (Ogden 1999, 3). Today, the piercing or jeweller’s saw is an indispensable item in a goldsmith’s workshop. For a long time, however, cutting sheet gold was done by means of chisels, or by piercing and filing (Ogden 1992, 162-3). Van Laer gives an elaborate description on how to “deurbreeken” (literally: “break through”) gold, silver, and copper with files, and how one can make the files themselves. In passing, he briefly mentions that one can also saw holes, very fine and thin, with a “Horlogiveer” (watch spring), provided it is tensioned in a “loopzaag” (a type of saw) or fixed in a handle like a file (1721, 144-6). He does not mention an actual jeweller’s saw. In prints of goldsmiths’ workshops, files are well represented, while the piercing saw is not in them (fig. 24). The first representation of a piercing saw in a goldsmiths’ workshop context is in the Encyclopédie of Diderot and d’Alembert, published between 1751 – 1766 (fig. 25). According to Ogden, the emergence of the piercing saw is one of the changes in the goldsmith’s industry implemented by the First Industrial Revolution, as it became possible to mass-produce fine sawblades. Earlier they had to be made by hand, in a time when it was custom for goldsmiths to make their own tools. The blades were difficult to make, they broke easily, and they were quite course, so making them would not be worth the costs, time and effort (1999, 3-6; 1992, 163).

The toolmarks on the edges of the book fittings show that they were not cut out by means of chisels or files. The wobbly lines, the awkward inlets in the corners to enable turning of the saw, and the square-ended cuts all indicate the use of some sort of sawing tool (fig. 26,27). A ‘modern’ jewellers saw, however, would generally give more precise and more pleasing results, suggesting that a forerunner of the jewellers saw – such as the Horlogiveer, described by Van Laer – or course and fragile, self-made sawblades were used for cutting the book fittings.

Both the sawn and the cast fittings show marks of engraving with a burin (fig. 22,27,28). A burin is a carving tool with a sharp lozenge-shaped point. Due to this point, the line tends to have a pointed ‘v’ shape where the tool enters and exits the metal (Cycleback 2018, 68). The force used in engraving caused the gold to be pushed over the sawn edge, indicating that these decorations were engraved after they were sawn (fig. 28). The engraving lines in the figure are very similar to the sawn decorations. In the figure’s head and strands from its sleeves the gold is also pushed over the edge. However, this can indicate engraving in the pattern before casting, or engraving of the cast product afterwards. A combination of both is most likely: Cellini describes how seals get their finishing touches after casting by working the silver with “punches, gravers and chisels, touching up and completing your subject now here, now there, figures, swags, arms, bodies, legs, all alike, accentuating them […] with you steel tools” (1898, 65).

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Figure 23. Detail front notebook. From an angle it is visible that the book

fittings are of thin, flat, sheet gold.

Figure 24. Title print of a book for gold- and silversmiths. The title

specifically mentions “snijden” (cutting). There are many tools depicted, but a jewelers saw is not among them. On the left a person is filing, on the right a person seems to be chiseling out a figure of sheet metal. Meester P.R.K. Titelprent Spits-Boeck, Rijksmuseum Amsterdam, Amsterdam (RP-P-2011-114-1), 1617, engraving. Credit: Rijksmuseum Amsterdam, http://hdl.handle.net/10934/RM0001.collect.504596.

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Figure 25. First depictions of the piercing saw as a goldsmith’s tool. Left: Diderot and d’Alembert, plate

VII. Right: Diderot and d’Alembert, plate XI.

Figure 26. Detail front, showing

saw marks. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

Figure 27. Detail chandelier back,

showing saw marks and

engraving. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

Figure 28. Detail back upper

right corner, showing engraving. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

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2.2.2 Stylus

The metal of the stylus has the same bright, yellow-golden colour as the book fittings. XRF analysis, taken on the point and on the tip of the stylus, indicated a similar alloy of gold (Au), copper (Cu), and silver (Ag) as the yellow-golden book fittings (see fig. 29 and Appendix II, no. 12,13). It can thus be concluded that they were made in the same workshop. Contrary to what Holzhausen says, the stylus is not a pencil, but a metalpoint, specifically a goldpoint.

2.2.3.2 Goldpoint

The term metalpoint can refer to the tool, the technique, as well as the image made with this tool. Until recently, drawings in metalpoint were all referred to as silverpoints. Although metalpoint styli were indeed usually made of silver (often alloyed with some copper), other metals, such as gold, copper, bronze, lead and lead alloyed with tin or bismuth, are also suitable (Burns 2012, 2; Dahm 2004, 75). Leadpoint and its alloys can be used on plain paper. For all other metalpoints the paper must be prepared with a mildly abrasive ground, so that when the stylus is drawn across the support, tiny metal particles are scraped off and deposited on the surface. The rough ground also retains the metal particles. These grounds are essentially aqueous white paints (e.g. bone white, lead white, or chalk) bound in animal glue, in which dry pigment is sometimes added for tinting (Dahm 2004, 75, 80; Burns 2012, 5-8).

Metalpoint types cannot be identified visually, because each metal initially leaves a grey line on the paper. Over time, the metal lines corrode. The corrosion colour can range from black to brown, to yellow-gold, depending on the metal type and ageing environment. Metals can thus take on different tones over time, just as different metals may take on a similar tone (Dahm 2004, 75). Artists’ styli are rarely preserved from the past, therefore technical analyses are generally performed on the drawings. By characterizing the chemical composition of the traces left on the paper, the metal alloy of the stylus can be determined (e.g. Dahm 2004; Reiche et al. 2004; Duval 2004). The fact that the stylus is still present in this case raises other questions, such as: why is the stylus a goldpoint?

Goldpoints were seldom used for drawings. The drawing Portrait of an elderly man attributed to Jan van Eyck and dated ca. 1435, was analysed by Ina Reiche et. al (fig. 30).In the drawing three different metalpoints were distinguished. Silverpoint with a small amount of copper was used for the figure, its robe and the lower cross line. For the hatching, silverpoint containing about 24 wt% was used. The inscriptions and the letter “r” written in the face were created with a goldpoint containing about 20 wt% silver. The same goldpoint was used for final revisions on the right pupil and on the mouth. The use of several metal styli in one drawing is exceptional. As an explanation for the use of goldpoint in the drawing, Reiche et. al. point at the

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difference in mechanical properties of a goldpoint: because it is much smoother than pure or copper-containing silverpoints, it is easier to write with (Reiche et al. 2004, 1661-2).

This raises questions about the function of the notebook. Was the stylus made of gold to make the writing easier, which would indicate that it was actually meant to be written in. Or did they use the same material as for the book fittings, making sure that they would fit together aesthetically and was the notebook meant as a showpiece? Also, it is presumed that everything is written with the goldpoint, but is this the case? Or was something else used for (part of) the writings, and was the stylus more decorative/functional as closing pin? This could be verified with further research with XRF or Macro-XRF analysis.

Figure 29. Indicating

where the XRF

Measurements were taken. Credit: Anneke Hoekstra

Figure 30. Jan van Eyck, Portrait of an elderly

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2.2.3 Settings

A gemstone setting is the element that securely holds a stone in place and attaches it to the object. Next to this function, a setting also has the purpose to enhance the clarity, colour and cut of the stone. Stones and metal are an aesthetically pleasing combination, because of their ability to reflect light and their lustre (Hesse 2007, 175; Untracht 1982, 599). Stones are set at the very end of the making process. The art object and the stone are subjected to external force during setting. Thus, the setter – a profession which developed separate from that of the goldsmith at the end of the sixteenth century – must be careful not to damage them during this process. Gold and pure silver are therefore not only preferred for aesthetic reasons, but also because of the workability of these metals, as they are relatively soft (Untracht 1982, 599; Falk 1980, 25).

Settings come in many forms, sizes, and types. Some are richly decorated; others are purely functional. Some settings have been used for centuries, whilst new types are still being developed. In the notebook three different kinds are found. The settings are all closed backed, meaning that the underside and the girdle (extreme edge) of the gemstones are completely enclosed by metal, so that no light passes through the setting from the base or below. Closed backed settings were used to a large extent until the mid-eighteenth century. Not only because they proved a secure way of setting stones, but also because the setting leaves room for gemstone enhancement, which will be discussed further on (see section 2.4 Gemstones) (Whalley 2012, S315). The first type of setting, a bezel setting, is used for the larger stones, both coloured and colourless. The second type is a small circular bezel setting, and the third type seems to be a cast setting. Both are used only for small colourless stones (fig. 31).

Type 1 is an example of a bezel setting with a simple decorative rim (fig. 32).A bezel setting in its simplest form is a thin strip of metal formed to the shape of the stone and soldered to the base metal. This way a container is created, in which the stone fits neatly. After the stone is placed in the container, the metal is pressed over the stone slope with setting tools to secure the stone tightly (Untracht 1982, 599).11_{A common trick is applied in the notebook’s type 1 settings: the} bezel’s edges are irregular where they meet the gemstone and they taper in to the top, giving the impression of larger, deeper and more regularly shaped gems (Whalley 2013, 80). This is especially the case in the settings for the colourless stones (fig. 33).Type 2 is a small circular bezel setting, used only for colourless stones. The same trick as described above is applied. The stones appear to be cleaved fragments from larger stones. The third type is a little unusual. The setting is very ornamental, shaped in a leaf-like form. Compared to the size of the stone, the setting is quite high and large. The setting appears on the cover six times, in the exact same size. The shapes are seemingly the same – although some settings look damaged, altering their shape slightly. This

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suggests that the settings are cast. The stones can be best described as flush-set or gypsy-set: the stone is sunk into the opening with its girdle flush with the metal body (Untracht 1982, 614). The edges surrounding the stone are, again, left very rough.

The metal settings are all discoloured and have lost their lustre. The discolouration ranges from a dull dark grey to a dull dark bronze on the type 1 and type 2 settings. The type 3 settings all have a dark bronze hue.

XRF measurements were taken on two spots on the front cover: on the side of a type 1 setting and on a type 3 setting (see fig. 34 and Appendix II, no. 10,11). A type 2 setting was not analysed. The XRF measurements show that the type 3 settings are made of copper (Cu), alloyed with a small amount of silver (Ag) and gold (Au). Because of the evenly dispersed, dark grey discolouration on all type 1 settings, it was suspected that they would consist largely of silver (Ag). From the end of the seventeenth century diamonds would often be set in silver rather than gold, because the sparkle of the stone is best set off by white metal (Ogden 2018, 159). The XRF results, however, rather surprisingly indicated an alloy of mainly gold (Au) and copper (Cu), in which only a small amount of silver (Ag) was detected. The spectrum is almost identical to the spectrum of the golden decoration’s tarnished spot. In fact, the spectra are so similar to each other that there are two possibilities: or the measurement is incorrect, due to interference of the surrounding golden decorations12_{; or the settings are indeed made of gold instead of silver. For the correct} interpretation of the object, and know the original appearance, XRF analysis should be performed on some more type 1 and 2 settings.

2.2.4 Conclusion

The book fittings, as well as the stylus are a gold-copper-silver alloy, with a high gold content. Some fittings were cast, others are sawn. The saw marks are rough, indicating that they were not made by a jeweller’s saw, but by some sort of precursor and can thus be dated before the First Industrial Revolution. Because the fittings and the stylus have the same composition, it can be concluded that they were made at the same time. The settings are all closed backed, which was a commodity until the mid-eighteenth century. The discolouration of the type 1 and type 2 settings suggests that they were made of silver, but this could not be confirmed with analysis. From the end of the seventeenth century setting diamonds in silver was preferred over gold, because the stone’s sparkle is best set off by white metal. The leaf-settings are mainly copper.

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3 .

1 _.

2 .

Figure 31. Detail front notebook,

showing the three different types of gemstone settings. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

Figure 32. Detail type 1 bezel

setting on the notebook’s spine. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

Figure 33. Detail fig.1c, lower

corner right, showing size enhancement trick.

Figure 34. Indicating where the XRF Measurements were taken.

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Figure 37. Diagram of a

champlevé enamel base. Credit:

Buckton 1982, 108.

2.3 Enamel

2.3.1 Technique: basse-taille

The enamels on the cover of the notebook are coloured light blue/turquoise, dark blue, black, green, and white. Except for white, the enamels are translucent. Enamel is essentially powdered glass, coloured by metallic oxides, fused onto a metal surface by means of heat. In the notebook the basse-taille technique is used, executed in the simplest form (fig. 35,36). Basse-taille is a form of champlevé enamelling. In the champlevé technique, meaning ‘raised field’, sunken recesses are prepared in the metal surface and filled with opaque enamel, which is contained within metal boundaries perpendicular to the metal base (fig. 37). In the basse-taille technique, meaning ‘shallow cut’, a pattern – simple or elaborate figurative designs – is created on the metal ground by chasing or engraving. The metal is filled with translucent enamels, rendering the pattern visible through the enamel. Light falling on the enamel passes through and is reflected by the metal. The technique therefore calls for a gold or silver base. Because gold will not form a discolouring oxide layer, it is preferred over silver (Buckton 1982, 101-2; Speel 1998, 7, 22). The patterns also roughen up the metal surface, providing extra grip for the enamel (Ward 2008, 188).

According to Richter Basse-taille enamelling was commonly used from the late thirteenth to the early sixteenth century, and, in the context of restorations and imitations of historic enamels, again in the nineteenth century (1994, 223). Speel specifies that the technique was especially popular for decorating Renaissance jewels, and in the eighteenth century for snuff boxes and watch cases (1998, 7) (fig. 38,39).

Figure 36. Detail figure 1a. bottom

hinge, showing the gouges in the substrate metal, where the enamel is chipped off.

Figure 35. Detail front notebook

showing the basse-taille enamelling. Credit: photography by Anneke Hoekstra using a HIROX Digital Microscope (20 x magnification).

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2.3.2 Enamel composition

To differentiate between Renaissance jewels – loosely defined as sixteenth/seventeenth century – and nineteenth century imitations or restorations, several recent studies have focused on quantitative chemical analysis of enamels to determine the relative amounts of elements present, and characterize the general compositions and colourants of the enamels (e.g. Wypyski 2002; Santos 2015; Drayman-Weisser and Wypyski 2005; Richter 1994). The enamels can be dated on account of certain changes in their overall compositions, colourants and opacifiers, introduced in the second half of the eighteenth and nineteenth century.

XRF measurements, which can be found in Appendix II, no. 1-5, of each colour were taken on the front of the notebook, providing qualitive data of their elemental composition (fig. 40). A downside of the method, is that some major and minor constituents of enamel are light elements and could not be detected: silicon (Si), sodium (Na), magnesium (Mg) and aluminium (Al).13 However, by comparing the results to recent studies and a contemporary treatise, information on

13_{See note 6.}

Figure 38. Anonymous (enamel on

reverse after design by Etienne Delaune), Prudence, Metropolitan Museum of Art, New York

(17.190.907), ca. 1550-60, back: 19th century, chalcedony mounted in gold with enamel, rubies, emeralds, diamond and pearl. Credit: Metropolitan Museum of Art,

https://www.metmuseum.org/art/col lection/search/193692

Figure 39. Anonymous, Snuffbox with blue translucent enamel,

Rijksmuseum Amsterdam, Amsterdam (BK-16242), ca. 1790 – ca. 1800, gold, metal, enamel. Credit: Rijksmuseum Amsterdam, http://hdl.handle.net/10934/RM0001.COLLECT.17796

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the general composition and the colourants of the enamels was yielded. The section relies for the better part on two studies by Mark Wypyski (2000; 2002) and a study by Van der Linden et al. (2010). These studies do not only point out differences in the composition of sixteenth and nineteenth century enamels, but include some changes and developments in seventeenth and eighteenth century enamels as well. The contemporary source that was used is The Art of Glass, an extensive technical work on glass, and one of the few written between 1650 and 1750. The treatise was originally written in French by Haudicquer de Blancourt in 1697 and anonymously translated to English in 1699.

2.3.2.1 General composition

The main constituent of enamel is silica (SiO2), obtained from ground flint or fine white sand. Since both gold and silver have a lower melting point than silica – respectively 1064°C and 960°C as opposed to 1710°C – fluxes in the form of sodium salts, potassium salts, or lead must be added in considerable amounts to reduce the enamel’s melting point. To prevent the glass from deteriorating under atmospheric environments, calcium, magnesium, and aluminium are added to the mix as stabilizing agents (Speel 1998, 43; Richter 1994, 225).

According to Wypyski enamels dating from the thirteenth and early fourteenth centuries have soda-glass compositions: a glass mixture with soda – sodium oxide (Na2O) – as the dominant alkali. These mixtures contain relatively large amounts of potassium, magnesium, and calcium oxides. Enamels from the early fourteenth and fifteenth century were found to have mixed-alkali compositions, containing relatively high levels of both sodium and potassium (with an

Writing the Biography of a Notebook: interpreting a richly decorated baroque notebook from the collection of the Rijksmuseum Amsterdam