Tortoise shell: the real thing and its imitations

This lorgnette from the Rijksmuseum, dated around 1900, reflects a long history of turtle shell fashion, as just one example of many objects made with the real material and, in this case, also possibly its imitation. The combination of its high cost and the decreasing number of turtles led to the popularization of imitations. They copy what is more commonly called “tortoise” shell and are made out of inexpensive replacements, reflecting the centuries-long obsession with this exotic material. Objects made of real turtle shell as well as its imitations, can be found in museum collections around the world. Today, we will take a look at such artefacts, how they were made, and how they were reproduced with ‘mock turtle’.

Anonymous. Lorgnet with tortoiseshell or celluloid frame on long octagonal handle with cannelure mid and bottom. ca 1900. Glass, tortoise. h25 x w10 x d1 cm. Rijksmuseum, Amsterdam.

Turtle scutes: what they are made of..

‘When we were little,’ the Mock Turtle went on at last, more calmly, though still sobbing a little now and then, ‘we went to school in the sea. The master was an old Turtle – we used to call him Tortoise – ‘

‘Why did you call him Tortoise, if he wasn’t one?’ Alice asked.

‘We called him Tortoise because he taught us,’ said the Mock Turtle angrily: ‘really you are very dull!’

In this passage from Alice in Wonderland (chapter IX), the Mock Turtle highlights a common misconception regarding the term “tortoise”. Within taxonomy, the word “tortoise” refers to land turtles, exclusively. In the vocabulary of decorative arts however, the term is usually applied to all types of turtle scutes, including those originating from marine species such as the green sea turtle, the focus of our project.

Important locations from which turtle carapaces were imported to the Netherlands were St. Eustatius, St-Martin and Saba in the Caribbean, islands that were under the direct command of the Dutch West India Company (WIC). The turtle’s shell, consisting of the carapace -the curved dorsal part of the shell- and the plastron -the ventral flatter part- is covered by scutes, which vary in shape, size and colour according to the species. Each consists of multiple layers of thin plate-like scales, tapering out at the edges. They are made of keratin, a material quite similar in composition to human hair and nails. The land-dwelling turtles do not shed and their scutes develop by the addition of keratin layers, whereas the marine turtles do shed.

Preparation of the scutes for cabinetmaking and everyday objects

In 17th-century Europe, skilled artisans started using turtle scutes to embellish various decorative art objects. Before the scutes could be used as decoration for furniture and small objects, they first needed to be prepared. The shells of marine turtles were often imported as raw material (the shell as a whole or the scutes taken off). Among the seven marine turtle species, two were particularly suitable: the hawksbill sea turtle (Eretmochelys imbricata) with blond-orange scutes, and the green sea turtle (Chelonia mydas), with scutes green on the outside and brown on the inside, with yellow to brown spots. To harvest the scutes, heat was used, a treatment most turtles would not have survived. A Caribbean hawksbill turtle of ca. 75 kg and 90 cm long could yield 2.5 kg of tortoise shell. A mature large green sea turtle of 112 cm (such as the Rijksmuseum one), probably up till 4 kg. Scutes can be between 1.5 and 3.5 mm thick.

The scutes are thermoplastic, which means they can be made flexible by heating or boiling and then shaped or pressed into a mold; once cooled down, they become rigid again. This way, the internal structure of the scutes, which consists of superimposed thin plates, is modified. After reshaping, the scutes were evened out with a plane and polished to make them transparent and shiny. For some small objects such as hair combs, the natural shape of the scute was preserved as it was suitable for the required shape. Cornelius van Dyk describes some of these characteristics well in his Osteolegia from 1680.

“In America there are four sea turtles: the first are big, weigh three to four thousand pounds; they lack a hard shell, such that one can cut in it with a knife, are full of traan (oil), and are unsuitable to eat. The second are green sea turtles, of moderate size; with examples of four foot wide; their skin is harder, covered by a small shell, as thick as horn, from which one makes lanterns. “In: Osteologia, of Naukeurige geraamt beschryving van verscheyde dieren, nevens hare historien, by Cornelius van Dyk, Apothecer & c tot Medemblik, published in Amsterdam in in 1680. p 156.

“It is known to most people, that one can make tobacco boxes from the shields, and very curious combs, that are called carnet. There is a large distinction in the shields, one being yellow spotted, another rosy, and brownish red, and sprinkled in black, which is kept for the best. These are the primary characteristics concerning turtles.”
In:
Osteologia, p 157.

The use of turtle scutes in decorative arts

The combination of the scutes’ transparency and shiny appearance made them especially coveted for the decoration of furniture. By the first half of the 18th century, cabinets with marquetry using turtle scutes, or ‘tortoise’, with inlays of other materials, were popular across the European continent, with workshops using this technique across Germany, Italy, France and the Netherlands.

Detail from the Dolls’ house of Petronella Oortman, anonymous, c. 1686 – c. 1710
The marquetry of the cabinet holding the doll’s house is made of tortoiseshell decorated with pewter inlays, by a cabinetmaker from France, who worked in Amsterdam for several years. (BK-NM-1010).

In France the cabinetmaker André-Charles Boulle (1642-1732) became the ébéniste of king Louis XIV (1638 – 1715), and was introduced by Colbert (one of Louis XIV’s ministers) to the king as “the most skilled in his profession.” He was chosen to furnish the Palace of Versailles, and developed his own style which made him an important precursor of French 18th-century furniture. He perfected a marquetry technique in which he used tortoise as an inlay material and embedded it with brass and pewter into ebony. This technique became very popular and was known as “Boulle work.”

André Jacob Roubo (1739-1791). 1774.  L’Art Du Menuisier-Ébéniste, Par M. Roubo Fils,… 3e Section De La 3e Partie De L’Art Du Menuisier. Paris: Saillant et Nyon, 335.
 
This plate in Roubo’s treatise describes a “Drawing of a piece of marquetry to be executed with tortoise and copper”.
With this technique, a special saw would be used to cut the pattern through a sandwich of sheets of tortoise and metal, so that “one has two pieces of marquetry, evenly cut, from which the flowers and the ornaments from one can be placed into the empty space of the other” . This is called “en contre partie” (p.1014 ). See this clip from the Bayerisches Nationalmuseum for a beautiful reconstruction.

The Rijksmuseum holds two toilet caskets attributed to Boulle (currently on display), which show the intricacy of this technique beautifully. One casket is decorated in première partie: copper in tortoise shell, the other in contre partie: tortoise shell in copper.


 André-Charles Boulle (attributed to). Toilet casket.  ca. 1685 –  1690. Tortoise shell, oak, ebony, brass, tin, bronze, gilding. h139.8 × w91.7 × d66.7 cm; h 84.7 × w 91.7 × d 66.4 cm; h 84.7 × w 86.5 × d 61.5 cm. Rijksmuseum, Amsterdam.
In this detail, the tortoise inlay has a reddish tone, most likely by superimposing the tortoise shell on a red coloured paper applied on the wooden support underneath it.

The rather transparent material could be ‘coloured’ by superimposing it on, for example, red paper, or a metal foil, or colour it with pigments or dyes.

Tortoise was not only popular for the making of large cabinets, but also for small everyday items. Many knife makers, fan makers, and other craftsmen such as the kammemaaker or comb maker, located in Amsterdam, used tortoise.

Jan Luiken, De Kammemaaker, serie Het Menselyk Bedryf, etching, 140mm x 81 mm, Rijksmuseum, RP-P-OB-44, 476.

As it was considered an expensive luxury product, most objects were made for the wealthy intended, for example, as personal or diplomatic gifts. The Rijksmuseum owns an embroidered letter case with a large comb, which belonged to the Dutch diplomat Thomas Hees (1634-1692), who served in Algiers, Tunis and Tripoli. This may have been such a gift.

Anonymous. Red Velvet Wallet, belonging to Thomas Hees (1634-1692). 1676. Leather (pocket), tortoiseshell (hair comb). h 16.7 × w 28.3 × d 0.8 cm. Mauritshuis, the Hague, on long-term loan to the Rijksmuseum.
«DE.EDELE.HEER.TOMAS.HEES.AMBASSADEUR.VAN.STAATE.GENERAEL.DER. VEREENICE.NEERLANDEN.1676 », “His excellency Sir Thomas hees Ambassador of the General States of the Kingdom of the United Provinces 1676”

Imitation of tortoise shell

During the 18th – 20th centuries, items made with tortoise remained very popular. An endless variety of objects was produced: optical frames, knife handles, toilet articles, book bindings, jewelry, tobacco and snuff boxes, such as this Tea Chest made out of turtle, attributed to Pieter Bartholomeus van Linde, Amsterdam, ca. 1755-1756, or this tortoise hair comb with twelve concatenated circles, ca. 1800 – 1824, or the small snuff box, only 5 x 8 cm, 1675-1700 (all Rijksmuseum), and much more. Tortoise was imitated because it was expensive, and became increasingly rare due to the continuous hunting of turtles.

The earliest trace of the use of horn as a “natural plastic” to copy tortoise dates back to the 17th century, with horn moldings made by the Englishman John Osborn (1581/4-1634). Horn could be heated and steeped in liquid, and shaped around hot irons to form buttons, combs, knobs and handles in natural colors. John Osborn moved to Amsterdam around 1600 and specialised in pressing horn and baleen using metal molds, methods he patented. In 1725, London became a horn-molding center, with several manufacturers producing snuff boxes, napkin rings, and combs. However, the brightness and transparency of the real scutes could never be obtained. With the increase in restrictions, plastics imitating tortoise progressively replaced the original material. The first synthetic material used to imitate tortoise was cellulose nitrate (celluloid), invented in Birmingham in 1855 by Alexander Parkes. Presented for the first time at the 1862 London International exhibition, it anticipated the modern aesthetic and functional uses of plastics.

Lantern with horn panes, ca. 1800-1899, Museum of Design in Plastics, Arts University Bournemouth (WCHL : 239) For the panes, the central portion of ox horn was used. Heated, . It was first heated, split and then scraped with a knife which made it thin and transparent. the thin sheets could be pressed to flatten them. This lantern is part of the Worshipful Company of Horners collection. Cornelius van Dyk mentioned the use of turtle shell for lanterns. This lantern is of course dated much later,and uses horn. In the 17th century horn was already used to replace turtle shell, hence this lantern could be quite close to van Dyk’s description.

Returning to the carapaces in the ijksmuseum, we can assume that they were seen as precious and exclusive objects and hence chosen as a painting support for important clients or patrons.

Whereas the carapaces were coveted for their scutes, the turtle meat was also sought-after. In a next blog, we will explore the culinary history of the green sea or soup turtle.

The Turtle Team

Bibliography

  • Hainschwang, Thomas and Laurence Leggio. 2006. The Characterization of Tortoise Shell and its Imitations. Vol. 42, 36-52.
  • Parsons, James J. 1972.“The Hawksbill Turtle and the Tortoise Shell Trade” in Études De Géographie Tropicale Offertes À Pierre Gourou. Vol. 38, Walter de Gruyter GmbH & Co KG, 45-60.
  • Rijkelijkhuizen, Marloes J. 2010. “Tortoiseshell in the 17th and 18th Century Dutch Republic.” Ancient and Modern Bone Artefacts from America to Russia.Cultural, Technological and Functional Signature, 97-106.
  • Rijkelijkhuizen, Marloes J., “Whales, Walruses, and Elephants: Artisans in Ivory, Baleen, and Other Skeletal Materials in Seventeenth- and Eighteenth-Century Amsterdam”, International Journal of Historical Archaeology, Vol. 13, No. 4 (December 2009), 409-429
  • Snodgrass, Mary Ellen. 2004. Encyclopedia of Kitchen History Routledge. Soulat, Jean and Caroline Solazzo. 2016. Des Caraïbes À La Métropole: Artisanat Et Commerce Des Peignes En Écaille De Tortue Marine à L’époque Coloniale. Vol. 16.

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