Past lives, A study on the condition of an eighteenth-century justaucorps.

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Past lives

A study on the condition of an eighteenth-century justaucorps

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Master thesis, University of Amsterdam Conservation and Restoration Specialisation: Textiles

Lorena Claudia Maria Dekkers Supervisor: drs. René Lugtigheid Second Reader: Jessica V. Hensel (MA) Date: 21 June 2019

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Acknowledgements

During the process of writing this master thesis I have had help from many people for which I am very grateful. First of all I would like to thank Suzan Meijer, head of the textile conservation studio of the Rijksmuseum Amsterdam to entrust me with this wonderful object. Secondly, I would like to thank my thesis supervisor René Lugtigheid for her constant supervision, critique and not unimportantly, support. You gave me confidence when I needed this but you always stayed critical. I would also like to thank Carola Holz, Marjolein Homan Free, Marjolein Koek and Mieke Albers from the Rijksmuseum Amsterdam for lending me their help, knowledge and support. Thank you to Madelief Hohé and Marije Blaasse of the Gemeentemuseum Den Haag who allowed me to examine their collection of justaucorps and supported me with all the additional information I needed. This also counts for Catharina van Daalen and Ninke Bloemberg of the Centraal museum Utrecht. The knowledge gained from the examination of your collection was priceless. To Art Ness Proaño Gaibor and Ana Serrano of the RCE for doing the analysis for me and fitting me into your schedule so last minute. I would like to thank Frida Sorber for sharing your knowledge and opinion on moiré and my object with me. Of the UvA I would like to thank, Emmy de Groot Maarten van Bommel, Maartje Stols-Witlox and Rene Peschar, for the entire thesis program and your critical questions that brought me to new insights.

A big thank you to Lieke Boerstra, Norman Perryman and Lotte-Ninja Wijdeveld who spared no time, to help me with my writing. Without you I would not have been as proud of the final product as I am today. Last but not least a special thanks to Alex King Perryman who was my rock, thank you for being so patient with me and always believing in me.

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Abstract

This research concerns an eighteenth century/ justaucorps with the inventory number BK-NM-8246. The object belongs to the Rijksmuseum Amsterdam since 1886, where it has been on permanent display for a long period of time. However, the object now is in such a bad condition that it is not on display at present. The focus of this thesis is to explain the cause of damage by examining the different factors that could have contributed to the current condition of the object.

The justaucorps outer-fabric is a gros de Tours on which a moiré effect is applied.1_{this moiré effect is caused by pressing the fabric which makes the}

light reflect in different directions. The gros de Tours is a warp faced rib fabric that consists of the weft, and two silk warp systems one of these is yellow and the other is purple. Together they create alternating purple and yellow ribs.

In the object multiple areas show a characteristic damage which looks like yellow threads that are floating loosely . These loose hanging threads are the bundles of linen floss that normally reside underneath the two-colored warp system and function as a filling thread. However, due to the embrittlement and loss of the yellow warp in certain areas, the linen is exposed and hangs loosely over the fabric.

To examine the damage In the object and the possible causes of it, the causes of damage are divided in two main categories. The first category are the intrinsic causes of damage, that are causes of damage that come from within the object and that have to do with the materials, dyes, weaving techniques but also the construction of the object. The second are the external factors that are explained as not intrinsic to the object, these are usually damages that are caused by its function. Examples of this are wear and tear, stains or light degradation.

To investigate the intrinsic causes of damage the RCE did analysis of the fibers with SEM EDX and UHPLCMS.2_{With these techniques research was done}

into damaging dyestuffs, possible bleaches, and the condition of the fibre. This was done by comparing the yellow and the purple silk fibre. It turned out that the yellow fiber was probably not bleached, dyed or weighted, making the degumming the most likely cause of deterioration.

The external causes of damage where examined by comparing similar justaucorps to object BK-NM-8246. Several areas of wear and tear could be distinguished. However, the permanent exposition of the object and the handling are most likely the causes of damage.

Keywords: justaucorps, men coat, eighteenth century, moiré, watered silk, intrinsic causes of damage, production of silk, external causes of damage, damage by function, wear and tear, SEM EDX, UHPLCMS.

1_{The moiré effect is explained in chapter 4.6 page 33.}

2_{RCE: Rijksdienst voor cultureel erfgoed. SEM EDX: Scanning electron microscopy – Energy-dispersive X ray}

spectroscopy. UPLCMS: Ultra-High Performance liquid chromatography with photodiode array detection coupled to a high resolution mass spectrometer.

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Samenvatting

In dit onderzoek staat een achttiende-eeuwse mannenjas in het Frans justaucorps genoemd, met inventarisnummer BK-NM-8246 centraal. Sinds 1886 is het object in het bezit van het Rijksmuseum Amsterdam, waar het voor een lange tijd in de permante collectie is tentoongesteld. Het object verkeert momenteel in een te slechte conditie om tentoongesteld te kunnen worden. Aan de hand van een aantal verschillende factoren die van invloed kunnen zijn geweest op de huidige staat waarin het object verkeert, zullen de oorzaken van de beschadigingen in deze thesis uiteen worden gezet.

De buiten stof van de justaucorps is gemaakt van een ripsweefsel genaamd gros de Tours. Het weefsel is naderhand behandeld met een moiré effect. Dit effect word gecreëerd doordat het licht in verschillende richtingen weerkaatst wordt. De gros de Tours bestaat uit één linnen inslagdraad en twee scheringen van zijde draden waarvan één geel is en de andere paars. Samen creëren ze afwisselend paarse en gele ribben.

Het oppervlak van het object vertoont op meerdere plaatsen karakteristieke beschadigingen. Het lijkt of de gele draden losjes boven de rest van het weefsel zweven. Deze loshangende draden zijn de linnen flos die zich normaal gesproken onder het tweekleurige ripsweefsel bevind en daarbij als een vuldraad fungeert. Vanwege de fragiliteit en het verlies van de gele schering op bepaalde vlakken, wordt het linnen blootgelegd en hangt het losjes over de rest van het weefsel.

Om de schade in het object en de mogelijke oorzaken ervan te onderzoeken, zijn de oorzaken van schade onderverdeeld in twee categorieën. Onder de eerste categorie vallen de intrinsieke oorzaken van schade. Deze schade wordt veroorzaakt van binnenuit het weefsel en hebben te maken met de materialen, kleurstoffen, weeftechnieken en de constructie van het object. Onder de tweede categorie vallen de externe oorzaken. Dit is schade die wordt veroorzaakt door de functie van het kledingstuk. Voorbeelden hiervan zijn: slijtage, vlekken of afbraak door licht. Met behulp van het RCE is er een analyse van de vezels met SEM EDX en UHPLCMS gedaan.3_{Om de intrinsieke oorzaken}

te achterhalen werd er gekeken naar schadelijke kleurstoffen, eventueel gebruikte bleekmiddelen en de conditie waarin de vezels verkeren. In deze analyse zijn de gele en paarse zijdevezels met elkaar vergeleken. Het bleek dat de gele vezels mogelijk niet gebleekt, geverfd of verzwaard zijn. Dit maakt het waarschijnlijk dat de schade aan de vezel veroorzaakt is tijdens het voorbewerkingsproces van het garen. Dit noemt men ‘ontgommen’.

Door object BK-NM-8246 te vergelijken met vergelijkbare justaucorps zijn de externe oorzaken van beschadiging onderzocht. Er zijn verschillende vlakken op het object waar slijtage te onderscheiden valt. Hoogstwaarschijnlijk zijn de beschadigingen aan de justaucorps veroorzaakt door de permanente

3_{RCE: Rijksdienst voor het Cultureel Erfgoed. SEM EDX: Scanning electron microscopy – Energy-dispersive X}

ray spectroscopy. UPLCMS: Ultra-High Performance liquid chromatography with photodiode array detection coupled to a high resolution mass spectrometer.

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tentoonstelling ervan in het Rijksmuseum en het daarbij nodige hanteren van het kledingstuk en de verplaatsing ervan.

Zoektermen: justaucorps, mannenjas, achtiende eeuw, moiré, intrinsieke oorzaken van schade, productie van zijde, externe oorzaken van schade, schade door slijtage, SEM EDX, UHPLCMS.

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List of abbreviations

RCE Rijksdienst voor het Cultureel Erfgoed. The cultural Heritage Agency of the Netherlands.

SEM-EDX Scanning electron microscopy – Energy-dispersive X-ray spectroscopy.

UHPLC-PDA-HRMS Ultra-High Performance liquid chromatography with photodiode array detection coupled to a high resolution mass spectrometer

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Introduction

The large costume collection of the Rijksmuseum Amsterdam is the oldest collection of costumes in the Netherlands.4_{The collection includes costumes from the seventeenth}

century up until more contemporary pieces. The fact that the museum has been collecting from early on and that there are so many pieces from different time periods, make this an important collection for research into textiles and fashion history. Costumes have also always been a favourite of the visitors of the museum. With the exhibition Catwalk (2016) the directors of the Rijksmuseum prominently showed off their appreciation and represented the importance of its costume collection, which was widely appreciated by the public. Due to its bad condition one object was not on display in this exhibition. Object BK-NM-8246 is an eighteenth-century men’s coat or justaucorps. Even though the structure of the justaucorps is still intact and is representative of the period it was manufactured in, its outer-fabric is badly damaged. The damage is very distracting and unfortunately makes the costume unstable which would make the justaucorps a bad candidate to include in an exhibition. This master thesis was written as part of the Conservation and Restoration master’s program of the University of Amsterdam, specifically the specialisation textiles. Its focus is on the cause of damage of object BK-NM-8246.

Aim and research question

Due to the state of the object it has been in storage for a very long time. Even though the probability of it going on display again is very small, researching the current state of the object is still very interesting from a material standpoint. The outer-fabric that was used to make this coat raises many questions, especially with the distinctive damages that have appeared. The moiré or gros de Tours is made out of three different fibres. Only one of these fibres, the yellow silk, is in a badly degraded condition. However, the other two fibres, a purple silk and a yellow linen, are in a near perfect condition. The aim of this research is to form a complete story of this object by closely looking at the object itself, compiling relevant literature and comparing the object to other similar objects. When all this information is gathered a, so to speak ‘object bibliography’, will be constructed telling the narrative of object BK-NM-8246 from its origins up until the present. This comparative research is focussed on the damage that could have been caused by wear and tear. However, other interesting discoveries were made regarding the construction of the object.

The main question raised by object BK-NM-8246 is how the distinctive damage that can be found in the outer-fabric of this object was caused, focussing on the distinction between the three different fibres of which the fabric was made. This issue was the basis to the main research question of this thesis:

- What is the cause of damage in the outer-fabric of object BK-NM-8246? -

To answer the main question a list of sub-questions was formulated that could lead to an overall answer.

4_{Mortier, Bianca M. du and Suzan Meijer “Moving forward together” in Refashioning and Redress:}

Conserving and Displaying Dressed. ed. Brooks, Mary M., and Dinah D. Eastop(Los Angeles: Getty Trust Publications, 2017). 44.

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Dekkers UvA 2019 ₁₄ These questions are:

• What is the historical context of the object?

• What is the condition of object BK-NM-8246 at present?

• What are the possible intrinsic causes of damage of this object? • What are the possible external causes of damage in this object?

Relevance for conservation

The research for this thesis is approached from a diagnostic standpoint. The aim of the research is to find answers to the posed questions but not with the objective of future conservation. However, this does not mean that the found answers wont contribute to the conservation or treatment of the object in the future. From a material standpoint this research is also of value because little research has been done on the damages that frequently occur in gros de Tours or the application of a moiré effect. The results found in this thesis through analytical techniques contribute to the conservation or preventive conservation of objects that are made with the same weave structure or finishing. Finally, a contribution to the conservation field is made in the comparison of six justaucorps from the same period.

Structure and methodology

To provide an academic context for this thesis and illustrate its relevance to the field of conservation the first chapter will be about the current scientific knowledge. Because next to nothing has been written about the object itself, research has been done to shed light on certain aspects of the object. These subjects are: the combination of fibers, the before and after treatment of the silk fibers, the outer fabric/moiré, the construction of the justaucorps and the evidence of wear and tear in historic costumes.

Chapter two will provide a historical context of the object. First the shape of the object will be discussed. In this discussion the object is placed in a certain time frame according to its shape. After the time frame of its manufacturing is established, the function that the object would have had during this period will be discussed. In addition, the provenance is an important aspect of the object. It can give clues to what conditions the object was in and accordingly what damages could stem from these conditions

The third chapter formally introduces the object but also the materials into the research by giving a detailed account of the condition of the object and the fibers. Together with Ana Serranno of the Rijksdienst voor het Cultureel Erfgoed, the fibres were analysed with Scanning electron microscopy – Energy-dispersive X-ray spectroscopy. The SEM was used to look at the surface of the fibers, the state of the fibers and looking for elements showing processes that could have caused damage to the fiber. This chapter comes with an elaborate condition report and condition map which can be found in the appendix I and II. Even though this chapter is short it is of great relevance as all the research in chapter 4 and 5 are based on the condition of the object.

Chapter four will focus on the possible intrinsic causes of damage that could be responsible for the current condition of the object. Intrinsic causes of damage are the processes that are inherent to the object. In this chapter the object is viewed from a very close view. As such there will be an analysis of the combination of fibers. After which the yarn and the before and after treatments of the silk are discussed. For this part of the chapter Ultra-High Performance liquid chromatography with photodiode array detection

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coupled to a high resolution mass spectrometer was done on the silk fibers by Art Ness Proaño Gaibor of the RCE. Zooming out even more the weaving structure and moiré technique is discussed. Concluding with the construction of the object in which tension caused by the construction is key.

The final chapter will consider the possible external causes of damage. To establish this kind of damage the changing function of the object over time also had to be considered. Damages caused by external factors can be abrasions to the surface of the textile or stains by the object being worn. If the object was exposed to exposition light deterioration could also be expected. In this chapter, the shape of the object is the starting point, discussing costume mounting and how the shape of the object can indicate what damage can be found where. Once established which damage could have been caused by intrinsic and external factors, the damage in the object was compared to five similar justaucorps from the Gemeentemuseum Den Haag and the Centraal Museum in Utrecht. Finally, the damages are set apart and the possible external causes are discussed.

Lastly the findings that are found in the chapters that are mentioned above will be compiled in the conclusion. Here an attempt will be made to answer the overall research question.

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1. Current scientific knowledge

In this chapter research that has been published so far about the subjects regarding this master thesis will be discussed. Since this thesis will focus on the damages that are intrinsic to the object versus the damages that are caused by external factors, this literature research will start by looking at what has been written about subjects that could intrinsically have caused the damage. Starting with the smallest detail, the fibers, and then zooming out to the construction. Firstly, literature that has been written about the combination of fibers of which the fabric has been made will be discussed. After this literature about the before and after treatment of these fibers is discussed. This encompasses the degumming, bleaching, weighting, and dyeing of the materials, making a distinction between the linen and the silk. This is followed by literature that has been written about the production method of the moiré effect that was applied to the fabric. The following section discusses literature about the construction of the coat, concluding the autonomous damage. Finally, the heteronomous damage will be discussed focusing on the recognition of wear and tear in historical garments.

1.1 The combination of fibers

While doing the preliminary material research it was discovered that the gros de Tours that was used to apply the moiré to is not only consists of two silk warps but also of a linen weft. There is little literature to be found about the combination of fibers or about the combination of linen and silk in particular. Mary Schoeser mentions in her book ‘Silk’ that textiles in historic collections that are made solely of silk generally are in a much better condition than those of combined fibers.5_{Schoeser adds that this might have to do with}

the reaction of different fibers to a fluctuating humidity. Silk reacts very differently to such fluctuations than linen. This is confirmed by Phillipa Scott in ‘The Book of Silk’ as she writes “each fiber survives according to its build in characteristics and previous treatment, but when different fibers are combined in a weave, their reaction to humidity alters. Pure silk survives better than a textile woven of silk combined with a different fiber”.6_This

assumption was the starting point for a hypothesis in this research. Building off of this hypothesis more information about the properties of silk and linen and their degradation processes can be found in the most common textile conservation handbooks.7

1.2 The before and after treatment of the silk fibers

The pre- and after treatment of the silk fibers could have negatively impacted the strength of the fiber. As can be seen in the Hirox photograph of the textile the purple fibers are intact and only the yellow silk warp fibers have been affected (Appendix III Fig. III.5). One explanation could be that the yellow fibers have undergone a treatment that weakened the fibers before they were dyed. Such treatments could be degumming, bleaching or the weighting of the silk, which can all impact the strength of the fiber.

5_{Schoeser, Mary. Silk. New Haven and London, : Yale University Press, 2007, 234.} 6_{Scott, Philippa. The Book of Silk. London: Thames & Hudson, 2001, 244.}

7_{Boersma, Foekje. Op de keper beschouwd : handboek voor het behoud van textielcollecties. 1e dr.}

Amsterdam: Stichting Textielcommissie Nederland, 2000.

Gohl, Erhard Paul Gottlieb., and Leo David. Vilensky. Textile Science: An Explanation of Fibre Properties. Melbourne: Longman Cheshire, 1993.

Landi, Sheila. Textile conservators manual.: London, Taylor & Francis, 2016.

Timár-Balázsy, Ágnes, and Dinah Eastop. Chemical Principles of Textile Conservation. London: Routledge, 2011.

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The article by Brooks, Mary & Sonia O’connor describes the process a silk fiber goes through from the excretion from the larvae to the end stages of the weaving . Particularly the section about degumming is very informative, in which it is explained that degumming to an extent, makes the fibers more vulnerable to pests and degradation but it does also make the fibers more susceptible to absorbing dyes. 8_{To estimate whether this bleaching}

treatment was harmful for the silk and has weakened it, it must first be established what the bleaching process for silk was at the time. There is more literature describing the bleaching of cotton and linen than there is about silk and wool. However, in The Art of Dying Wool, Silk, and Cotton, a historic source from 1789, a detailed explanation of the process of sulphurization is given.9_{In the source it is also described that it is only to be done}

to silks that had to be absolutely white, for example for wedding dresses. However, the silk fiber that is investigated is yellow. The question is whether or not this was bleached as it might not have been necessary to do so. The article ‘European silk production method and possible implications for textile conservation approaches’ by Mary Brooks and Sonia O’Connor, mentions that “watered silk was not bleached using a Sulphur method as it prevented the moiré effect from forming”.10_{This is corroborated by the historical source}

which mentions the same.11_{This is a very interesting observation as it would mean that the}

yellow fibers were not bleached as a clear moiré effect can be seen in the fabric of the coat. The last treatment that could have affected the yellow fiber is the weighting of the silk. There are many conservation related articles written about this treatment however most of them are focused on the period after 1870’s as this is when the metal salts weighting began to become popular. Metal salts silk weighting is known to be a destructive non reversible treatment on a silk fiber. But as it was not done before 1870 other weighting treatments will have to be considered. The treatments that were done before 1870 consist of vegetable weighting with animal glue or sugar. Thea van Oosten writes in ‘Degradation investigation into the degradation of weighted silk’ that all of these treatments are removed when the silk is washed and also that they have no influence on the stability of the silk.12_{The fact that the weighting agents would be removed when washed is important}

to keep in mind as the moiré making effect usually encompasses a form of wetting as well. This would mean that the weighting agent that was used could be affected, which would be an argument for not using it. The article by Brooks and O’ Connor mentions that gall nut tannins could have been used as these were used to weight light colored fibers like yellow and pink.13_{However, Marei Hacke mentions in her article ‘Weighted silk: history analysis}

and conservation’ that these bleached tannins were not developed until 1890 which is too late for this object to be considered.14_{The last article about the weighting of silk that is}

8_{Brooks, Mary & Sonia O’connor, European silk production method and possible implications for textile}

conservation approaches’. SFJ Jubilee conference, 1997. N.P.

9_{Hellot, Jean, Macquer, Pierre Joseph, and Lepileur d’Apligny. The Art of Dying Wool, Silk, and Cotton.}

Translated from the French of M. Hellot, M. Macquer, and M. Le Pileur d’Apligny. London: printed for R. Baldwin, 1789. 276.

10_{Brooks and O’connor, European silk production method and possible implications for textile conservation}

approaches, N.P.

11_{Hellot, Joseph and d’Apligny. The Art of Dying Wool, Silk, and Cotton, 278.}

12_{Oosten van, Thea. “Degradation investigation into the degradation of weighted silk” in Contributions of}

the central research Laboratory,(Amsterdam : The Laboratorium, 1994). 18.

13_{Brooks and O’connor, European silk production method and possible implications for textile conservation}

approaches, N.P.

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interesting to consider is ‘Understanding the ageing behavior of 19th/20th century tin weighted silks’ written by Paul Garside, Paul Wyeth and Xiomei Zhang.15_{In this article the}

condition of historic silk is examined by looking at its pH and tensile strength. The conclusion is that both an increased acidity and a decreased tensile strength indicate a deterioration of the fiber. However, the tests that are done in this article require samples that are bigger than what would be possible to take from coat BK-NM-8246. SEM EDX however requires smaller samples and would be a good option.

1.3 The outer fabric /moiré

A lot of information can be found on moiré silk and the production of the moiré effect. The article ‘Moiré gaufre, plisse’ of Frieda Sorber is a good starting point as it gives information about the history of moiré but also its production processes through history.16_{The article}

by G. Gilonne can give a good indication of the kind of moiré it is, although Sorber mentions that naming the kind of moiré by name can also cause confusion in the long run as they can mean different things in different languages and such.17_{The production process of moiré}

is also mentioned in the famous ‘Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métier’s by Diderot and d’Almbert, here prints of the press/calender that was used specifically in the eighteenth century and the way the silk was folded before it was pressed can be found.18_{For information about the gros de Tours in which the moiré effect}

is produced ‘Clothing Technology’ by Eberle et al. can be used.19_{This book gives a fairly}

modern insight into textiles and their weaving structures but the gros de Tours has not changed. However, none of these books and articles talk about the width of the rib that is usually used for a moiré nor do they talk about the thickness of the gros de Tours that was regularly needed.

1.4 The construction of the justaucorps

In this sub-category literature concerning historical patterns and the construction of men’s clothing will be discussed, as the construction could be of influence on the deterioration of the justaucorps. Literature about the fit and historical patterns are plenty full. There are eighteenth century sources as well as modern sources. The Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers is a good example of an eighteenth century source. It shows how patterns are laid out on a width of fabric. This also tells us something about the width of the fabric that was regularly used and what the selvedge was, which indicates the warp and the weft. An even more important contemporary source that also shows the construction of eighteenth-century men’s coats is ‘Art du tailleur’ by Garsault.20

The book by Norah Waugh gives more insight into the patterns that were used.21_{Waugh is}

particularly interesting for the pattern drawings of the interlinings. These are of great 15_{Garside, P., Wyeth, P. and Zhang, X. "The inherent acidic characteristics of silk, part II" Preservation}

science no.7 (2010): 126-131.

16_{Sorber, F., “Moiré Gaufré, Plissé” Stichting textielcommissie Nederland. Vlaggen en Vaandels.}

Textielveredeling, ed. A.J. Graaf (Amsterdam: stichting textielcommissie Nederland 1999). 113-125.

17_{Gilonne, G. Soieries de lyon: documents techniques et pratiques sur l'art et la fabrication de soieries, tissus}

á mailles, tulles, dentelles, et leur utilisation dans nouveauté. 1948.

18_{Author anonymous. ‘Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers. D.}

Diderot, Le Rond d’Alembert, J. (red.) Paris: Le Breton, 1752.

19_{Eberle, Hannelore, Ring, Werner, and Kilgus, Roland. Clothing Technology : from Fibre to Fashion. 6th}

[English] ed. Haan-Gruiten: Verlag Europa-Lehrmittel, 2014. 75.

20_{Garsault, M. de, Description des Arts et Métiers, L’Art de Tailleur, Paris, 1769.}

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importance to the research as they might have an influence on the outer-fabric. Waugh also gives an elaborate account on how the male fashion changed between 1680 and 1800, which is of great help in correctly dating object BK-NM-8246. Finally, der Kinderen-Besier cannot be overlooked since she wrote shortly about object BK-NM-8246 but also explains the changes in fashion in the eighteenth century.22

1.5 The evidence of wear and tear

Wear and tear are clear products of external causes of damage Philip Sykas gives a comprised list of research that has been done about this subject.23_{However the articles}

given here are more based on analytical research like SEM EDX. For example the atlas of fiber fracture which analyses pictures of damaged fibers in order to determine what external factors caused the damage.24_{From a more practical standpoint in determining}

wear and tear without using analytical techniques Mida and Kim give a check list of what to look for when looking for signs of wear and tear.25

1.6 The position of this thesis within current scientific knowledge

The aim of this thesis is to gain a better insight into the possible causes of damage on object BK-NM-8246. Focusing on the effect that the production of the materials had on the aging of this object vs. the effects of the use of the coat. Many production methods were considered like material itself, the treatment of these materials, the combination of materials, the making of the moiré effect and the construction. Additionally, the use and the damage hereof were asserted by comparing the damage of object BK-NM-8246 to other similar justaucorps from the Centraal Museum in Utrecht and the Gemeentemuseum in The Hague.

The research into the combination of linen and silk will add to what little knowledge there already is, as not much is written about this mix of these fibers in particular. As a case study this research can be an interesting starting point for further investigation.

Also interesting for the conservation field is the overview of possible before and after treatments of silk that is given and the effects it has on the fibers. It also explores the differences in strength and damage between light and dark colored silks.

As said previously much literature exists about moiré and the production of it. This research might contribute to the field as it is written from a conservation perspective, as the possible damages that can possibly occur by applying the moiré effect to silk is rarely discussed in literature.

The final subject that is researched in this thesis regarding the production is the construction of the coat. Again, many sources can be found on the construction of a justaucorps but not from a conservation standpoint. This thesis zooms in on the construction of the coat and how it might cause damage. For example, interlinings and their 22_{Kinderen-Besier, J.H. Der, and Nederlansch Museum Voor Geschiedenis En Kunst Amsterdam. De}

Kleeding Onzer Voorouders: 1700-1900 : De Kostuumafdeeling in Het Nederlandsch Museum Voor Geschiedenis En Kunst Te Amsterdam. Amsterdam: Van Looy, 1926.

23_{Sykas, Philip A., “Investigative methodologies: Understanding the Fabric of Fashion” in The Handbook of}

Fashion Studies, ed. Sandy Black, Amy de la Haye, Joanne Entwistle, Agnes Rocamora, Regina A. Root and Helen Thomas ( London: Bloomsbury, 2013). 235-267.

24_{Hearle, John William Stanley., Brenda Lomas, and William D. Cooke. Atlas of Fibre Fracture and Damage}

to Textiles. Cambridge: Woodhead Publishing, 2006. 18.

25_{Mida, Ingrid, and Alexandra Kim. The Dress Detective: A Practical Guide to Object-based Research in}

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stiffness in comparison to the outer fabric are discussed. However, as this damage only occurs in combination with movement, as the last subject the heteronomous damage is important to regard together with this subject.

The damages of object BK-NM-8246 were compared with other similar justaucorps and as such a template of were damage in these kinds of coats usually occur was established. This can be of relevance to research of similar objects in the future.

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2. Historical context

In this chapter the historical context of the object will be explained. First T

the fashion of the period is described and whether the model of the coat fits within this fashion frame. To do this a detailed description of the coat is given which will be compared to research that has been written about fashion in this time. The function of the coat will also be examined within this period.

Second, the provenance of the object will be discussed by discussing its previous and current owners. The objects position within the museum then and now will be discussed and its current values within the museum will also be explained. This information was gathered by looking into the provided institutional records, the archive of the Rijksmuseum and by consulting the textile conservators of the Rijksmuseum.

2.1 Object description and placement in fashion

The object is an eighteenth-century justaucorps dated between 1735 and 1765 by the Rijksmuseum Amsterdam (Figure I.1, I.2, I.3) It is made of a purple and yellow silk gros de Tours that has a moiré effect applied to it. The bodice and skirt are lined with a blue silk twill and the sleeves are lined with a white plain weave linen (I.10, I.9). The justaucorps is made of two front and two back panels. It has a round neckline with no collar. On both sides of the front panel there are 17 buttons and buttonholes. The buttonholes are only partially open as only the eleven upper ones are functional. The rest of the buttonholes are purely decorative and are closed with the blue lining covering the back. On both sides of the front panels are deep pockets, placed between the outer fabric and the blue lining. The opening of the pocket is V-shaped and five buttons are sewn under this V-shape. On top of this pocket a pocket flap is positioned that has five buttonholes of which three are opened. The back seam that connects the two back panels runs from the neck until the beginning of the back slit. This slit is decorated with seven horizontally positioned buttonholes on each side which are purely decorative as there are no buttons to go with the holes. The side seams which connect the front with the back panels start under the sleeves and run down until the pocket flap. This is also the height where the back slit starts. Also, at this height a button can be found on each half of the back panel, this is where the skirt of the coat starts. The area under the button consists of three triangular pattern pieces that form a fan, this gives width to the skirt and it also functions as open slits. The fan shaped pattern pieces are stiffened by an interlining and stiffly stand out from the body. On the underside of the slit, a button keeps the fold of one fan shaped pattern piece closed. The sleeves consist of an upper and under sleeve with a cuff that is only slightly wider than the sleeve. The cuff which is 21cm wide and 13 cm high is decorated with three buttons and buttonholes which are decorative.

2.2 Date

In this description of the object some aspects are mentioned that could indicate a certain time period. Starting with the back of the justaucorps that consists of two panels. The fact that two panels were used instead of one, gave the opportunity to make the coat more fitting.26_{Justaucorps with one back panel were made until 1725 after this time justaucorps}

with two back-panels emerged. Another important indicator is that the coat has no collar, this was done because the collar would be almost entirely covered by the big wigs that 26_{Der Kinderen-Besier, De Kleeding Onzer Voorouders. 79.}

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were fashionable at the time.27_{Standing collars appeared from the 1760’s.}28_{The stiffening}

of the triangular inlays that give a wider appearance to the skirt was fashionable until the 1760’s as well. Another detail of the justaucorps that was subject to the changing of fashion was the cuff size. Earlier coats had larger and wider cuffs who would be folded back so the silk lining would show. These would be fastened by buttons. Smaller cuffs that do not show the lining but only the outer fabric appear from around 1730.29_{Even though the current}

cuffs on the coat seem to be from a later time period they are not entirely indicative of the time, because when looked up closely three clusters of stitch holes can be found above the cuff. These holes can also be seen from the inside on the linen lining. The stich holes might indicate that the coat was altered for some reason. One option could be that it was to be worn by another person with shorter arms but, the coat shows no signs of alterations in other places where this would be expected. It is more likely that the cuffs were altered to abide by the changing fashions, as this is a small detail that was easily altered. It could be that these holes are also the reason for the rather broad dating of the coat by the Rijksmuseum as wider cuffs would make the coat of an earlier dating.

The object is a justaucorps that is dated between 1735 and 1765 by the Rijksmuseum Amsterdam. The model of the coat is consistent with the fashion during this time. However, it would be more accurate to date the object at the early ends of this time period 1735-1750. Because the entire model within the skirt, the stiff interlining, and the round neck, point to the first half of the eighteenth century. An explanation for it to be dated by the Rijksmuseum until 1865 can be found in the alteration of the cuffs which could have been done to abide to changing fashions as this is a small adjustment to make the model last longer in fashion.

2.3 Original function

The clothing of the male and female elite in the eighteenth century can be divided in three categories: grand parure, parure and negligée.30_{Christian-Campbell explains that these}

terms are explained differently for men, and that a grand parure is also known as a grand habit. Clothing that was worn in court originates from the ceremonies that were customary at the French court.31_{For men for example this meant that their justaucorps had to be}

embroidered with precious metals. Also, their buttons would have to have jewels on them, and their wigs would have to be a certain style. The clothing of the courtiers was to represent the power and grandeur of the French king in all its magnificence.32_{Grand habit}

would mostly be worn for royal gala’s and ceremonial happenings during court. The parure is a style of clothing that would be worn at court but yet was a slightly toned-down version of the grand parure. Then there is the negligée, which in France was worn at home, on a walk, during visits that had no official character, at domestic parties and on many other occasions.33_{Although, negligée sounds like a more relaxed style that would be worn at}

home the textiles would still be very luxurious and often consisted of silk. This is also the case for the fit of the clothing, negligée did not mean that the comfort of the clothing 27_{Der Kinderen-Besier, De Kleeding Onzer Voorouders. 78.}

28_{Waugh, The Cut of Men's Clothes. 53.}

29_{Der Kinderen-Besier, De Kleeding Onzer Voorouders. 81.} 30_{Der Kinderen-Besier, De Kleeding Onzer Voorouders.16-17.}

31_{Chrisman-Campbell, Kimberly. Fashion Victims: Dress at the Court of Louis XVI and Marie-Antoinette. New}

Haven and London: Yale University Press, 2015. 111.

32_Ibid.

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improved a lot as the restricting shapes were often still worn. Object BK-NM-8246 would most likely be categorised as negligée as the material is very luxurious but it had no further decoration whatsoever. Even the buttons are of the simplest kind.

2.4 Provenance

History of the object: In 1886 the object was donated to the Nederlandsch museum voor Geschiedenis en Kunst by Abraham Bredius (1855-1946) who was vice president of the museum at the time. The collection of this museum was housed inside the Rijksmuseum building at the time and later became part of the Rijksmuseum collection. After consulting the archive for any possible donation documentation, it was concluded that no such documents existed. During this time of transition from the Nederlandsch museum voor Geschiedenis en Kunst to the Rijksmuseum Amsterdam these documents were often not kept up to date or made at all. This means that no further provenance is known about this object. However, the fact that it was donated by Bredius can be indicative to a degree, as he was a connoisseur and collector of many objects. It is known that Bredius had a special affinity for costume. This was exceptional at this time as historical costumes were not yet appreciated in the way they are now.34_{Bredius collected costumes from different times}

and cultures and even had a cabinet in his own Bredius museum that was dedicated to costumes. 35

The coat was donated as part of a set together with a vest BK-NM-8244.The vest is a long sleeved under vest that is dated by the museum at 1730. However, upon inspection of the two objects it cannot be said with certainty that they indeed are related, as hardly any similar physical features can be found between the objects. The objects are both made of a ‘watered silk’ but the gros de Tours weave is much finer in the vest than in the justaucorps. Also, the justaucorps is made of a purple and yellow colour with a blue lining and the vest is made of a white silk with a blue lining. Yet, the blue linings have a different weave structure and a different hue. Also, blue linings in clothing were not uncommon in the eighteenth century and can be found in many examples of justaucorps. Finally, the buttons are different in both objects. If the two garments were to be a set, one would at least expect the same buttons. Thus, it cannot be concluded that they are a set. This is also corroborated by the fact that the two objects are dated differently by the Rijksmuseum. By physical comparison of the two objects, a relation of the objects seems unlikely, with the only relation that they both were donated to the museum by mister Abraham Bredius at the same time. Finally, it must be said that Der Kinderen-Besier does mention the justaucorps and vest as a set in De Kleeding Onzer Voorouders: 1700-1900 : De Kostuumafdeeling in Het Nederlandsch Museum Voor Geschiedenis En Kunst Te Amsterdam.36_{In this book Der Kinderen-Besier discusses the costume department of the}

Nederlandsch Museum voor Geschiedenis en Kunst te Amsterdam. The information that is given about the object is limited but she does treat the two objects as a set. Der Kinderen-Besier also mentioned that breeches once belonged to the set but that this was a modern addition that was made in 1924, the breeches do not exist in the collection anymore.37

However, the fact that breeches were made for the set does indicate that the justaucorps has been on display at a certain time. Unfortunately, no pictures survive from this time so 34_{du Mortier, Meijer, “Moving forward together” 238.}

35_{Dutch newspaper: de Tijd, 22-06-1957. 4.}

36_{Der Kinderen-Besier, De Kleeding Onzer Voorouders. 89.} 37_Ibid.

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it cannot be said if the current damage was already present at the time. Furthermore, it is not specified if the author thinks that the justaucorps and the vest are a set or, if she treats them as a set because the museum regards them as such. Also, Der Kinderen-Besier dates the objects from 1750 to 1770 as opposed to the 1730-1765 of the Rijksmuseum. Even though this is a smaller time span, it is on the late side especially if she thinks the vest belongs together with the justaucorps as a set because, long-sleeved vests were usually used in the first half of the eighteenth century.38

2.5 Heritage value

The issue of value deserves a separate paragraph as its currentvalue and its heritage value differ from each other but are important for the research of the object. That the coat was outfitted with replica breeches a jabot and lace flounces in 1924 indicates that the justaucorps has been on show around this time. There are no pictures of this object in these expositions who survived. However, the object must have been in a considerably better state than it is now, as it would be very distracting to show the object with the damage that it currently has.

An object in a museum that can be shared with the public represents certain values for the museum. Der Kinderen-Besier writes in her book De Kleeding Onzer Voorouders: 1700-1900 that the costumes are of value for the arts and crafts, theatre-arts and craft schools. But also because of their artistic values within the arts that were practiced at court.39_{In this case the values could be aesthetic, historical, associative end educational.}

Aesthetic value is applicable in this case because of its lustrous appearance, the moiré effect in the silk reflects the light that hits the fabric and must have given a luxurious feel to the object. The historical value of this object is obvious as it is a representation of what the elite wore almost 200 years before. Lastly the object also had an associative value, to explain this value an article by Barbara Laan is referred to.40_{This article discusses the}

creation and demise of the department of the Nederlandsch Museum voor Geschiedenis en Kunst in its original size and structure, with particular emphasis on the decorative arts and interior design. Laan mentions here that the museum started to make a distinction between Dutch traditional wear and historical costumes in 1916. After this separation the costumes that were left were characterized as historical costumes (that had been from a specific important person, mostly stadholders) and costumes that from a textile historic point of view were of importance (that belonged to city people who were part of the elite).41_{This could mean that the collection was particularly moulded and assembled for}

the elite culture. Which coincidently were also the people who would go to the museum at this time. The associative value that comes to play here is that the collection of the museum shows objects of the elite to the elite, it creates an associative moment between the spectator and the object. Lastly the educational value can simply be explained as the object show examples of what the elite wore 200 years earlier. Also, der Kinderen-Besier describes how some of the objects have been used to make new patterns and how the study into the textiles is still ongoing during the writing of her book.42

38_{Waugh, The Cut of Men's Clothes. 54.}

39_{Der Kinderen-Besier, De Kleeding Onzer Voorouders. 3.} 40_{Laan,“Kunstnijverheid en interieur,” 69-102.}

41_{Laan,“Kunstnijverheid en interieur,” 88.}

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The current value to the Rijksmuseum has to be represented by different values as previously mentioned as the object is in such a state that it cannot be put on display anymore. It has thus lost its aesthetic, educational and its associative value. The current values can be described as: historical, and research. The historical value still applies to the object as it is an object that is indicative of its time. It can, however, be argued that this value is no longer applicable as the object will not be shown to the public anymore. The research value of this object is apparent as the Rijksmuseum has made it possible for a master student to research this object. The research is about the history, materials, production and damages of the object.

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3. The condition of BK-NM-8246

(Appendix I and II)

In the previous chapters the object was placed in a scientific and historical context. This chapter will focus on the condition of the object at present. This determination of the damage is necessary because it will help to indicate the possible intrinsic and external causes of damage that will be discussed in chapters 4 and 5.

An assessment of the condition will be given outlining the most important parameters and the corresponding condition assessment. To start, the overall condition of the object will be discussed, after which the damage is split into different categories. Here a short description of these damages will be given. This chapter comes with a damage map and the condition report which can both be found in the appendices.

3.1 Overall condition

Before an overall condition is defined it must be said that determining the condition of an object is not an exact science. The determination of the condition is built up out of the conservator’s personal knowledge and experience in combination with other previously established classification systems out of which the conservator can choose. In addition, there is a direct connection between the determination of condition and the context it is in. As such criteria like, function, purpose, expectation and use play a significant role in the determination of the condition.43_{Furthermore it is also possible to use analytical}

techniques to establish the condition of certain aspects of the object. For example, the flexibility or brittleness of the fibres which can be tested with tensile strength tests or examined with SEM-EDX, respectively. In this research a combination of all of the above is used to determine the condition of the object.

Overall, the justaucorps is in a poor condition. For this condition classification the system by Jonathan Ashley-Smith is used in which poor is described as: “ restricted use, probably unstable. Action desirable”.44_{The classification of poor was chosen because the}

object is very fragile even though this is not apparent at first sight. This means that the object can only be handled sparingly and with a lot of care.

The main problem in the object can be found in the outer-fabric. This is a gros de Tours on which a moiré effect is applied. The gros de Tours is a warp faced fabric that consists of the weft, which is made of three bundles of untwisted linen floss, and two silk warp systems. These warp systems also consist of floss, but they are made of silk. As each warp has its own colour, together they create ribs with alternating colours (Appendix III Fig. III.3) In the object multiple areas show a characteristic damage which looks like yellow threads that are floating loosely (Appendix I Fig I.4, I.5 and Appendix II green) These loose hanging threads are the bundles of linen that normally reside underneath the two-coloured

43_{Dean, Sully. "Conservation, Theory and Practice. Materials, Values and People in Heritage}

Conservation." The International Handbooks of Museum Studies: Museum Practice. Ed. Conal McCarthy.: Museum Practice Vol.2. Chichester, West Sussex: John Wiley & Sons Ltd., 2015. 293-314.

44_{Ashley-Smith, Jonathan. Risk Assessment for Object Conservation. Oxford [etc.: Butterworth-Heinemann,}

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warp system and function as a filling thread. However, due to the embrittlement and loss of the yellow warp in certain areas, the linen is exposed and hangs loosely over the fabric.

3.2 Condition of the fibres

(Appendix VI. VIII.)

A preliminary examination of the state of the fibres was done with the Hirox type KH-8700 microscope. This method showed that of the three fibres that are present, purple silk, yellow silk and yellow linen, the yellow silk was in the worst condition. After examination with the Hirox microscope the fibres were examined with the SEM. This microscope can produce a very clear image of the surface of the fibre. For this examination six samples were taken of each fibre in an area that was exposed and one in an unexposed area (Appendix VI). The taking of the samples in the exposed area was straightforward, as it could be taken from an area that was already damaged. For the samples of unexposed fibres, a small sample was cut from inside a seam that was open (Appendix VI.1, 3, 5, 6). This piece was then dissected with tweezers under the microscope. Although taking a sample by cutting is fairly invasive, it was taken only after consultation with the Rijksmuseum Amsterdam. Also, the area from which it is taken was not visible and has a large seam margin. Taking a sample in this way ensured minimum mechanical damage on the fibre, giving a representative view of the damage in the sample for SEM.

The SEM image of the three fibres showed that all the fibres were very clean (Appendix VIII all). Also, there was no visible evidence of a coating which rules out an after treatment like animal glue, Arabic gum or sugar. Also, the purple silk and the yellow linen were in a very good state, flexible and with no signs of deterioration. The yellow fibres on the other hand showed many small fragments of broken fibre, as well as cracks and breaks in the longitude of the fibre (Figures VIII. 4,6,7). This can indicate material fatigue.45_Other

breaks that can be found were concentrated in small areas (Figure VIII.3) These breaks could have been caused by the application of the fibre to the sample stub under the SEM. The fibres were pushed down on the sticky side of the stub with a tweezer, most likely causing this damage pattern (Figure VI.4). All the fibres were applied to the sample stub with the same tweezer by the same person yet none of the other fibres exhibited the same damage pattern. The small fragments of fibre, the breaks in the longitude of the fibre and the concentrated damage pattern indicate that the yellow silk is very fragile.

3.3 Most important parameters of the condition assessment

(Appendix I and II)

The most important parameters of the condition assessment are Structure/ loss

• Loss of the yellow silk warp, overall on outer-fabric especially around creases, due to degradation of yellow silk, (Figures I.4 and 5. II Damage map 1 and 2). This is the most apparent and extensive damage that the object suffered.

Creasing distortion

• The object shows some obvious creasing. Most of the creases are centred around the waist and the armpits. These are places where there is more movement in the

45_{Hearle, John William Stanley., Brenda Lomas, and William D. Cooke. Atlas of Fibre Fracture and Damage}

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body hence these are common places to find this damage.46_{This damage is one of}

the most noteworthy damages as it is a factor in the loss of silk warp.

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4. Damages caused by intrinsic processes

In the previous chapter the condition of the object was discussed, based on this damage the possible intrinsic causes of damage will be discussed. Intrinsic causes of damage are all the processes that come from within the object, that could affect the original state of the object. The materials, the mix of materials, the before and after treatment of the yarns, the weaving of the fabric, the finishing of the textile and the construction of the justaucorps are all considered. The explanation of these findings will start with the smallest detail of this object, which is a fibre. From there the research will expand up to the construction of the coat as a whole. This chapter discusses mainly the outer-fabric of the coat as this is where the majority of the damage can be found.

4.1 Materials

The outer fabric is made of a duo-toned silk and linen gros de Tours. Onto this gros de Tours a moiré effect is applied. In §3.2 (Structure loss) the damage of the fabric is explained. The structure of the gros de Tours consists of two silk warp systems that each have their own colour, purple and yellow. The rib is created by the weft which consists of three bundles of linen that are completely covered by the silk warp. Silk is categorized as a lustrous and translucent fibre by Gohl and Vilensky in their book Textile science an explanation of fibre properties.47_{They point out that the lustrous effect of this fibre is due to the high}

proportion of light reflected very evenly by the smooth surface of the fibre. The greater the lustre, or the more light reflected, the lighter the appearance of the colour of the fibre.48

The reasoning behind choosing a silk for this material is obvious as it enhances the moiré effect that is applied to the gros de Tours afterwards. As silk is an animal fibre, which is protein, and linen is a plant-based fibre which is cellulose, the different properties of the two materials react to changing conditions in different ways. As explained in Table 4.1, but the most important differences and similarities are briefly discussed here. Linen is a bast fibre: the bast is the part that transports water through the plant. This is why it has very good water absorbing capabilities 65% of its own dry weight with a RH of 65% and a temperature of 20o_{C. As opposed to silk which can absorb 11% of its own dry weight under}

the same conditions.49_{Another difference is that linen is very heat resistant while silk is}

very sensitive to heat. Also noteworthy is that silk likes to reside in a slightly acidic environment while linen likes a slightly alkaline environment. 50_{This is important because}

the degradation product of linen is acidic.This should create a favourable environment for the silk. However, it is the silk that is in a bad condition. Finally, both fibres are very sensitive to degradation by visible light and UV.51

47_{Gohl, Vilensky, David, Textile Science, 201.} 48_Ibid.

49_{Boersma, Op de keper beschouwd, 21.}

50_{Timár-Balázsy, Chemical Principles of Textile Conservation, 26.} 51_{Gohl, Vilensky, David, Textile Science, 201.}

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Cellulose (linen) Protein (silk)

Functional group Hydroxyl + aldehyde Carboxyl group + amino

group Chemical composition 64.1% cellulose 16.7%

hemicellulose 1.8% pectin 2.0% lignin

Fibroin (and sericin) Wet polymer is very elastic at

room temperature

DP 36000 300-3000

Crystallinity 90% crystallinity ? more than

silk crystallinity 65% To 75% Very crystalline

Thermal properties Very heat resistant Very heat sensitive

Decomposition begins at 310 o_C ₁₇₀ o_C

Ignition temp? - 420 o_C

Tg 220-230oC 175 oC

Elastic plastic nature Very inelastic More plastic than elastic

Light Absorbs ultraviolet radiation strongly below 200 nm slightly between 200 and 300 nm and weakly up to 400 nm

220-370 nm causes

yellowing and photo

deterioration of silk

Photo-oxidation Photo-oxidation

heterogeneous reaction

Effects of moisture Water decreases the glass transition temperature of cellulose

Moisture regain 12% or (7% at 65%) humidity 11% or (8.9 to 10.1%) at 65% humidity

Ideal relative humidity 45-60% +-5% below 40% desiccation above 65% swelling and colonization of micro organisms

Below 40% desiccation

In liquid water Swelling

40 %? 16.5%-18.7% direction 1.3% in axial transverse direction

moisture absorbing capacity 65% of its own dry weight with a RH of 65% and a temperature of 20 o_C

11% of its own dry weight with a RH of 65% and a temperature of 20 o_C

Hygroscopic nature Absorbent Very absorbent

Ultraviolet and visible

light Especially vegetable fibres Damaging to Silk is the most sensitive of the natural fibres to electromagnetic radiation Exposure to ultraviolet

radiation and light causes vegetable fibres to turn yellow/brown or fade. Become acidic

The result of photo oxidation is a discoloured, rigid and mechanically weakened silk fibre.

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Tannins make silk fibres very

vulnerable to

electromagnetic radiation Particularly sensitive to acids

Likes alkaline environments Likes acidic environments Table 4.1 the differences and similarities of linen and silk, information derived from Timár-Balázsy, Chemical Principles of Textile Conservation and Gohl, Vilensky, David, Textile Science.

4.2 Mixed materials

Mary Schoeser mentions in Silk that textiles made up from mixed materials are often in a worse state than textiles that only consist of one fibre type. The reason for this can be the way that the different fibres react to different environmental fluctuations.52_{As mentioned}

in 5.1 silk and linen can both absorb moisture. However, linen has a much greater ability to regulate water and swells more than silk.53_{The gros de Tours is woven in such a way that}

the silk warp entirely covers the linen weft. This is most unfortunate as the linen has the largest swelling ability. One can imagine that as the linen swells the silk will have less space and will come under pressure. This is problematic as silk is very crystalline and as such, not elastic. Another problem with the mixing of fibres is that the fibres will rub against each other when they swell in time causing abrasions on the fibre and making them brittle. This is called material fatigue.54

These may be plausible explanations for the cause of damage that suggest the conclusion that it could be a factor in the deterioration, but it is not the main cause of damage. This can be deduced from the fact that only the yellow silk is brittle, and the purple silk is intact. If only the tension of the linen swelling caused this damage to the yellow silk, the purple silk would also be damaged, but it is not.

4.3 The yarn and the treatment of the yarn

(Appendix III)

As can be seen in the Hirox images of the gros de Tours all of the yarns consist of non-twisted bundles of fibres (III.1,2 and 5). This is possible because the silk has very long fibres as does the linen, and it is called floss. Floss can be characterized as “Yarn made up from a bundle of fibres that is virtually non-twisted”.55_{Again the reason for choosing a untwisted}

yarn is the fact that it has an overall smoother surface than a twisted yarn, making it possible to reflect more light, thereby contributing to the moiré effect, a technique that heavily relies on the reflection of light.

4.4 Degumming and bleaching

(Appendix VIII.)

Silk comes from the silk worm, bombyx mori. The silk worm spins a cocoon of silk, which is processed by humans into silk threads. These are used for many purposes of which the textile production is a main segment. The production process of silk is long and complicated 52_{Schoeser, Silk, 234.}

53_{Boersma, Op de keper beschouwd, 51.} 54_Ibid.