The Secrets of Textile Fragments Hidden Inside the 19Th Century Chasuble from Dubrovnik

materials

Article Revealing the Origin: The Secrets of Textile Fragments Hidden inside the 19th Century Chasuble from Dubrovnik

Danijela Jemo 1,* and Djurdjica Parac-Osterman 2

1 Art and Restoration Department, University of Dubrovnik, 20000 Dubrovnik, Croatia 2 Faculty of Textile Technology, University of Zagreb, 10000 Zagreb, Croatia; [email protected] * Correspondence: [email protected]; Tel.: +385-20-446-032

Abstract: This paper presents the analysis carried out during the textile conservation–restoration process with the goal to reveal the secrets of textile fragments hidden inside the 19th century chasuble from Dubrovnik. The discovered textile fragments were investigated by modern instrumental methods and compared with the original textile from the 19th century set of liturgical vestments, which the chasuble belongs to. In addition, all other old repairs and treatments on the chasuble that had significant impact on the historic textile over time were investigated and assessed. The polymer type of the fibres was established by microscopic examination and infrared (ATR FT-IR) spectroscopy. A comparison of type of fibres and textile construction parameters, both from fragments and from the original textile, was carried out in order to determine their possible associations. Based on UV-Vis and HPLC identification of chemical composition of dyes in extracts from textile fibres, both from textile fragments, old repairs and authentic historic textile, it was possible to designate some common characteristics of dyes as important factors in determining its authenticity.

Citation: Jemo, D.; Parac-Osterman, Keywords: natural dyes; SEM-EDX; FTIR-ATR; HPLC; 19th century textile; Dubrovnik D. Revealing the Origin: The Secrets of Textile Fragments Hidden inside the 19th Century Chasuble from Dubrovnik. Materials 2021, 14, 4650. 1. Introduction https://doi.org/10.3390/ma14164650 Archaeological and ancient textiles and their dyes represent valuable sources for the study of clothing and textiles during human history [1–3]. Studies on the history of clothing Academic Editors: Tanja Pušić, and textiles reveal the religious, social and legal regulations of clothing, as well as their Mirela Leskovac, Tihana Dekanićand cultural significance and historical, aesthetic or sentimental value [4]. In the absence of Ivo Grabchev valid documentation and origin data, textiles must be defined relying on their specific design and patterns, decoration, fabric types and weaves, dyes, through iconography, Received: 30 June 2021 modern ethnographic surveys and contemporary scientific analysis [2,4,5]. Accepted: 12 August 2021 Published: 18 August 2021 Based on interdisciplinary approaches and the involvement of specialists from different fields, it is possible to achieve a better understanding of the ancient textiles and their

Publisher’s Note: MDPI stays neutral characteristics [6]. with regard to jurisdictional claims in The analysis of historic material always involves balancing the usefulness of the published maps and institutional afﬁl- information that can be obtained against risk to the integrity of the object. Conservation– iations. restoration treatment is a key to the long-term preservation of textiles. Directions and recommendations given by the European Network for Conservation—Restoration Edu- cation (ENCoRE) describe the conservation–restoration process from examination, the highest level of research and diagnosis up to direct intervention or preventive action, if required [6]. Appropriate analytical methodology approach for the analysis of textile ﬁbres Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. and dyes in textile conservation may give a useful indication of the history and origins of This article is an open access article a textile, but also how the material has been processed in the past and what methods of distributed under the terms and conservation treatments to apply in order to preserve it for the future [7]. conditions of the Creative Commons Each historical item is unique and can tell us its story. Their interesting life span Attribution (CC BY) license (https:// represents a valuable source for different types of case study research. During history, creativecommons.org/licenses/by/ especially the years of the Second World War and after, old textile materials derived from 4.0/). different sources were often employed to make new garments or to repair those that were

Materials 2021, 14, 4650. https://doi.org/10.3390/ma14164650 https://www.mdpi.com/journal/materials Materials 2021, 14, 4650 2 of 20

damaged [2,7–10]. Worn parts were often cut away, while those which remained preserved were used as patches in repair work. Such is the case with the cultural heritage items from Dubrovnik investigated in this paper. The Republic of Ragusa (today’s city of Dubrovnik) existed from the 14th to the 19th century. It was an aristocratic, free city-state, with highly developed maritime trade and a diplomatic network. The textile industry of Dubrovnik was closely related to the production of woollen fabrics (Artis Lane). Since the production of silk fabrics was poorly represented, in the 19th century, they were mainly imported from the Orient, the Czech lands and England. One of the highly important crafts in the Republic was the dyeing of fabrics (Artis Tinctoria), first mentioned in the conclusions of the Grand Council from 1392. Natural dyes of plant and animal origin were used to dye the fabrics. Sources of natural purple-red dyes used in Dubrovnik area from the 14th to the 19th century were brazilwood (Caesalpinia brasiliensis), madder (Rubia tinctoria L.), kermes (Kermes vermilio L.) and Tyrian purple (Murex trunculus)[11]. The set of liturgical vestments is one of the five different sets (red, green, black, white and gold color) from the church of the Annunciation of the Blessed Virgin Mary (built in 15/16th century) from the island of Lokrum in front of the city of Dubrovnik. Based on the study of construction technique and distinctive stylistic features, all sets were dated back to the second half of the 19th century [12]. The items are the property of the Diocese of Dubrovnik, but due to the lack of previous documentation, the original owner is unknown. According to the parish priest, it can be assumed that during the 20th century, the sets were brought from the Dubrovnik Cathedral for the purpose of performing a liturgical service on the island. In 2008, with the beginning of the construction works on the island church, they were sent to the restoration workshop at the University of Dubrovnik. The main goal was to make an inventory list with a main documentation. Provided data served as a basis for protecting and preserving that cultural heritage and being put on the list in the Register of Cultural Property of the Republic of Croatia. A case study about the authenticity of subsequent interventions at the 19th century chasuble from Dubrovnik is highlighted in this paper. The chasuble is a part of a set of liturgical vestments that additionally consists of a velum, maniple, burse and stole (Figure1). Subsequent interventions discovered inside the chasuble include added textile fragments, which are presumed not to belong to the original item, and old stitching repairs done by hand, with yellow and red tone thread, as attempt to arrest or reduce the rate of textile deterioration. In the “Textile of Parament: Church Textiles of the Croatian History Museum”, Paviˇcić mentions the fraternity weavers’ workshops linked to the cathedrals alongside the coastal part of the Croatia—in Dubrovnik, Split and Trogir. Their members were knitted and tailored clothes and repaired older church vestments [13]. Some items made in these workshops were composed of various fabrics that originated from different damaged items. Those items previously had a different original purpose or originated from various historic periods, which greatly complicates their dating. Important historical information helpful to date this liturgical set refers to the maniple that a priest once used to wear over his arm. In 1967, the Roman Catholic Church removed the necessity of using a maniple in the liturgy [14]. In order to preserve liturgical sets from Dubrovnik, the undertaking of conservation– restoration treatment was decided. These works were carried out at the University of Dubrovnik. During the conservation–restoration process of the chasuble and velum material, samples were taken and different analyses were performed [12,15,16]. Identification methodology implied the use of non-destructive and micro-destructive testing, using modern instrumentation methods and analysis techniques. MaterialsMaterials 20212021, 14, ,x14 FOR, 4650 PEER REVIEW 3 of 213 of 20

a. b. c.

FigureFigure 1. Set 1. ofSet liturgical of liturgical vestments: vestments: (a) chasuble, (a) chasuble, (b) velum, (b) velum, (c) maniple, (c) maniple, (d) burse (d) burse and and(e) stole. (e) stole.

In theIn a“Textile combination of Parament: of physical, Church biological Textiles and/or of the chemical Croatian damaging History factors, Museum”, different Pavideteriorationčić mentions ofthe cultural fraternity objects weavers’ may worksh occur [9ops,17, 18linked]. Some to the changes cathedrals in historic alongside textiles the can coastalbe caused part of bythe manufacturing Croatia—in Dubrovnik, processes. Split The processand Trogir. of artificial Their members silk weighting were knitted in the late and19th tailored and clothes early 20th and centuries repaired canolder cause chur rottingch vestments and weakening [13]. Some ofitems textile made fibres, in these leading workshopsto breakage were over composed time [9 ].of Additionally, various fabric metals that salts originated based on from iron different used as adamaged dye fixative items.(mordant) Those items to give previously a rich dense had blacka different colour original can deteriorate purpose fibresor originated [9,18,19 ].from various historic periods,In the middle which ofgreatly the 19 complicates century, synthetic their dating. dyes Important came into historical the scene information and gradually helpfulsuppressed to date this natural liturgical dyes that set refers were exclusivelyto the maniple used that until a priest then for once colouring used to ofwear textiles over [ 20]. his arm.The inventionIn 1967, the of Roman synthetic Catholic dyes Church had a big removed impact the on necessity methods of of using dyeing a maniple in respect in to the application,liturgy [14]. fastness properties, colour range and availability. In orderDifferent to preserve instrumental liturgical techniques sets from and Dubrovnik, methods the of analysisundertaking allow of us conservation– to better under- restorationstand historical treatment textiles, was decided. reducing These the rate works of textile were deteriorationcarried out at and the increasingUniversity the of lifetimeDu- brovnik.of fragile During artefacts. the conservation–restoration The application of scientific process methods of the chasuble to the conservation and velum material, of cultural samplesheritage were commenced taken and different at the end analyses of the 18th were century, performed and just [12,15,16]. over a hundred Identification years meth- later they odologywere stillimplied restricted the use to spotof non-destructive tests, optical microscopy and micro-destructive and some spectroscopy testing, using techniques modern [ 21]. instrumentationHowever, today methods modern and analytical analysis techniquestechniques offer a great deal of information extending theIn scopea combination of classical, of physical, chemical andbiological physical and/or analysis. chemical Physical damaging characteristics factors, different of the fibres, deteriorationsuch as colour, of cultural longitudinal objects andmay cross-sectionaloccur [9,17,18]. shape, Some changes can be observed in historic with textiles transmitted can be causedlight [7 by,22 ,manufacturing23]. Infrared microspectroscopy processes. The process provides of artificial complementary silk weighting information in the late to opti- 19thcal and microscopy early 20th whencenturies identifying can cause polymer rotting typeand weakening of fibres, but of istextile also ideallyfibres, leading suited toto the breakageexamination over time of organic[9]. Additionally, materials metal such assalts natural based dyes on iron [24 –used26]. Dayas a dye analysis fixative in historical(mor- textiles and archaeological finds poses particular challenges, especially as the percentage dant) to give a rich dense black colour can deteriorate fibres [9,18,19]. of dyes are usually much lower compared to recent, contemporary textiles. Scanning In the middle of the 19 century, synthetic dyes came into the scene and gradually electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) suppressed natural dyes that were exclusively used until then for colouring of textiles and XRF can provide valuable information about the composition of inorganic aspects, [20]. The invention of synthetic dyes had a big impact on methods of dyeing in respect to for example, mordant used with the dyestuffs [7,9,27,28]. Until the second half of the application, fastness properties, colour range and availability. 19th century, archaeological and historical textiles were dyed with natural dye sources [3]. Different instrumental techniques and methods of analysis allow us to better under- High-performance liquid chromatography (HPLC) combined with spectrophotometric stand historical textiles, reducing the rate of textile deterioration and increasing the life- UV-Vis detection [29] and mass spectrometric detection [30] is used for characterisation of time of fragile artefacts. The application of scientific methods to the conservation of cul- dyestuffs or pigments that may have been used as colorants in historical textile materials. tural heritage commenced at the end of the 18th century, and just over a hundred years Principles of textile conservation involve systematic study, documentation and scien- latertific they investigation were still restricted of textiles. to To spot offer test a mores, optical complete microscopy understanding and some of each spectroscopy textile artefact

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that is unique and irreplaceable, it is necessary to determine its construction, materials, condition and authenticity [31]. Analytical methodology applied in this work was adapted to the specific demands that arise when cultural heritage material is analysed. The primary aim of this study was the application of scientific methods to the conservation–restoration of cultural heritage that brings a new dimension to the understanding of a historical object. Supplemented by the comparative analysis, it was a useful tool to explain differences and similarities between the original historic textile and the fragments, revealing the hidden secrets. Identification of the chemical composition of dyes gave valuable data about the cultural heritage textile located in the area of Dubrovnik.

2. Materials and Methods 2.1. Materials In textile conservation, material investigation carried out on textile samples of original artefacts consider taking small amount of all different types of warp and weft, since they may contain different component materials [9,32]. To identify and compare fibre content and present dyes, a representative amount of warp and weft thread samples of the original historic textile was taken from the chasuble and velum item. The samples of threads from the textile fragments and stitches on chasuble were also taken. Considering the value and the fragility of cultural heritage material, the threads were cut away from the hidden parts or mechanically damaged areas without damaging the integrity of the object. For each instrumental method applied in this work, up to 5 millimetres of thread were cut away from the warp (Sample 1, 3, 5, 7, Table1) and the weft ( Sample 2, 4, 6, 8, Table1), as well as from the stitches (Sample 9 and 10, Table1). The optimum sample length used for the investigation is determined based on the satisfactory results obtained by testing such a small amount of sample, respecting the fact that the cultural heritage is explored. Based on microscopic observations and the information about the general structure of the fibre obtained from the surface, we conclude that the quality of the samples is satisfactory to Materials 2021, 14, x FOR PEER REVIEW provide enough evidence for the identification [15]. 5 of 21

Materials 2021, 14, x FOR PEER REVIEW 5 of 21 Table 1. Samples taken from the main fabric of chasuble and velum. Table 1. Samples taken from the main fabric of chasuble and velum. (a) Chasuble(a) Chasuble Dama Damasksk Fabric Fabric (Figure (Figure 1a)1a) Table 1. Samples taken from the main fabric of chasuble and velum. (a) Chasuble Damask Fabric (Figure 1a) red tone siredlk warp tone silk from warp damask from damask fabric; fabric; Sample 1 Sample 1 multifilamentmultiﬁlament yarn spun yarn in spun the s-direc- in the s-direction red tone silk warption from damask fabric; Sample 1 multifilament yarn spun in the s-direc- red tone cotton weft;tion 2 s-spun yarns plied Sample 2 red tone cotton weft; 2 s-spun yarns plied Sample 2 in the z-direction red tone cotton weft; in2 s-spun the z-direction yarns plied Sample 2 (b) Velum Damaskin the z-directionFabric (Figure 1b) (b) Velum Damask Fabric (Figurered1b) tone silk warp from damask fabric; (b) Velum Damask Fabric (Figure 1b) Sample 3 multifilament yarn spun in the s-direc- red tone siredlk warp tonetion silk from warp damask from damask fabric; fabric; Sample 3 Sample 3 multifilamentmultiﬁlament yarn spun yarn in spun the s-direc- in the s-direction Sample 4 red tone cottontion weft; z-spun

Sample 4 red tone cotton weft; z-spun Sample 3 red tone cotton weft; z-spun (f) Mapping Fragments (c) Fragment 1—Damask Fabric redDiscove tone redsilk Undewarp rfrom the Lampas damask Fabricfabric; Location and the Stitches Sample 5 multifilament yarn spun in the s-direc- on(f )theMapping Chasuble Fragments (Marked (c) Fragment 1—Damask Fabric redDiscove tone redsilk Undewarption rfrom the Lampas damask Fabricfabric; Locationin and Black) the Stitches Sample 5 multifilament yarn spun in the s-direc- on the Chasuble (Marked tion red tone cotton weft from damask fab- in Black) Sample 6 ric; z-spun red tone cotton weft from damask fab- Sample 6 ric; z-spun (d) Fragment 2—Damask Fabric Attached to the Interlining Inside the Chasuble

(d) Fragment 2—Damask Fabric Attached to the Interlining Inside the Chasuble red tone silk warp; multifilament yarn Sample 7 spun in the s-direction red tone silk warp; multifilament yarn Sample 7 spun in the s-direction

black arrows indicate red Sample 8 red tone cotton weft; z-spun black arrows thread indicate red Sample 8 red tone cotton weft; z-spun stitches thread (e) Stitchingstitches Threads Designated as Subsequent Interventions (e) Stitching Threads Designated as Subsequent Interventions red tone cotton yarn; 4 z-spun yarns Sample 9 plied in the s-direction red tone cotton yarn; 4 z-spun yarns Sample 9 plied in the s-direction

Sample 10 yellow tone cotton yarn; s-spun

Sample 10 yellow tone cotton yarn; s-spun Materials 2021, 14, x FOR PEER REVIEW 5 of 21

Table 1. Samples taken from the main fabric of chasuble and velum.

(a) Chasuble Damask Fabric (Figure 1a) red tone silk warp from damask fabric; Sample 1 multifilament yarn spun in the s-direction

red tone cotton weft; 2 s-spun yarns plied Sample 2 in the z-direction

(b) Velum Damask Fabric (Figure 1b)

Materials 2021, 14, 4650 red tone silk warp from damask fabric;5 of 20 Sample 3 multifilament yarn spun in the s-direction

Table 1. Cont. Sample 4 red tone cotton weft; z-spun

(c) Fragment 1—Damask Fabric Discovered Under the Lampas Fabric (f) Mapping Fragments red tone silk warp from damask fabric; Location and the Stitches Sample 5 multifilament yarn spun in the s-direc- on the Chasuble (Marked tion in Black) red tone cotton weft from damask fab- Sample 6 ric; z-spun

(d) Fragment 2—Damask Fabric Attached to the Interlining Inside the Chasuble

red tone silk warp; multifilament yarn Sample 7 spun in the s-direction

black arrows indicate red Sample 8 red tone cotton weft; z-spun thread stitches (e) Stitching Threads Designated as Subsequent Interventions

red tone cotton yarn; 4 z-spun yarns Sample 9 plied in the s-direction

Sample 10 yellow tone cotton yarn; s-spun

2.1.1. Original Historic Textile The set of Liturgical vestments from Dubrovnik is composed of five different pieces, made from various textile materials (Figure1). Based on the previous visual and tactile analysis, we came to the conclusion that all other items of the set are made of the same red damask materials found on the chasuble (Figure1a) and velum (Figure1b) [ 15]. Therefore, it was enough to take only samples of damask fabric from the chasuble and velum for the analysis (Table1a,b). The examination of samples under an optical microscope revealed that fabrics were made of two types of fibre. It is not a mixture of fibres, but a weave structure where all warp samples are 100% silk; the same applies to the weft samples taken from all fabrics, which are 100% cotton. This was confirmed by FTIR-ATR analysis that gave a high percentage of matching with the reference fibre, further discussed in Section 3.1.1. Materials 2021, 14, 4650 6 of 20

2.1.2. Old Repairs on Chasuble—Textile Fragments and Stitches In the condition report, based on a close examination of the chasuble, various damages were noted such as surface impurities, stains and damage caused by wear and tear, defor- mation of the material, damages in the weave structure, loss of seam integrity on the stitch line joining two pieces of fabric, discoloration, folds, creases and previous repairs [15]. There are also subsequent interventions present that appeared over time, such as red damask fragments (Table1c,d) and repairs by sewing with red and yellow threads (Table1e ). During conservation and restoration works, damask fragments were found hidden inside the chasuble (Table1f). They are located on the backside of the object, under the lampas fabric (Table1c), as well as a small fragment attached to the interlining inside the chasuble and stitched with red thread (Table1d). Discovered fragments beneath the cross on the backside of the chasuble are used to support damaged lampas fabric, distributing the weight of the damaged textile evenly. The true meaning and role of Fragment 2 will become understandable only later, after the analysis. Sample descriptions taken from Fragment 1 and Fragment 2 are given in Table1. Stitches that have been sewn by red and yellow thread, designated as old repairs or subsequent interventions on the chasuble, are given in Table1e. These stitches appeared over time during use, found on damaged parts of the original damask and lampas fabric. The ﬁrst one is dense lines of yellow stitching which overlay the surface of lampas fabric, following the yellow weave pattern. The second repair is the red thread of the support stitch, whose role was to securely anchor the lost weft threads from damask fabric. The same red thread stitch was found in the lampas fabric and in Fragment 2 (Table1d).

2.2. Methods Performing the research according to the algorithm shown in Figure2, each technique Materials 2021, 14, x FOR PEER REVIEWprovided different data useful for analysis and identification purposes. Yarns or threads7 of from 21

the textile fabrics or seems, as well as the dye extract from those samples, were investigated.

1.1. Stylistic features 1.1.1.Visual Artefact Manufactur- and Construction technique Examination ing and Dating

1. Identifica- 1.2. Fabric Technical tion of Textile 1.2.1. Digital Microscope Fabric properties Analysis Materials

1.3. Morphological in- 1.3.1. Optical Microscope Analytical formation and fiber 1.3.2. SEM Fiber origin approach 3. Comparative molecular structure 1.3.3. FTIR-ATR Analysis

2.1. Colored 2.1.1. FTIR-ATR fiber Chemical 2. Identifica- 2.1.2. SEM-EDX Composition of tion of Dyes 2.2. Dye 2.2.1. UV-Vis Spectroscopy Dye Extract 2.2.2. HPLC

FigureFigure 2. 2.AnalyticalAnalytical Methodology Methodology Applied. Applied.

Visual analysis of the items’ construction, such as cutting parts and structural seams, gave valuable information about the shape of the artefact, production and style, relevant for the typological dating. Fabric design and patterns revealed the fabric type characteristic of the specific historical period (Figure 2, block 1.1.). Using a digital microscope, fabric technical analysis was performed, obtaining data about the fabric properties, such as weave structure and type, yarn twist and fabric density. This information was important for the historic textile documentation, as well as for the comparative analysis (Figure 2, block 1.2.). Different techniques and data science tools were used for comparing and classifying textile fibres (Figure 2, block 1.3.). Optical microscopy was used to examine each sample in order to verify that the samples are homogeneous and do not contain any other fibre types (Figure 2, block 1.3.1.). The polymer type of the fibres was established by optical microscopy, SEM and FTIR-ATR (Figure 2, blocks 1.3.1, 1.3.2., 1.3.3.). The identification of the dye components present on the coloured fibres was performed by FTIR-ATR, SEM-EDS, HPLC and UV-Vis Spectroscopy, on both the solid samples and dye extracts (Figure 2, blocks 2.1. and 2.2.). The analysis provided data on the chemical composition of each dye present in the sample to confirm dye sources used as colorants on the investigated historical textile materials. Finally, a comparative analysis was applied to identify and match textile fabrics, yarns, fibres and dyes in order to confirm their authenticity and to establish common features (Figure 2, block 3.). Abbreviations: SEM, (Scanning electron microscope), FTIR-ATR (Fourier-transform infrared spectrometry with attenuated total reflectance), SEM-EDX (Scanning electron microscopy with an energy dispersive X-ray Spectroscopy), HPLC (High performance liquid chromatography).

Materials 2021, 14, 4650 7 of 20

Visual analysis of the items’ construction, such as cutting parts and structural seams, gave valuable information about the shape of the artefact, production and style, relevant for the typological dating. Fabric design and patterns revealed the fabric type characteristic of the specific historical period (Figure2, block 1.1). Using a digital microscope, fabric technical analysis was performed, obtaining data about the fabric properties, such as weave structure and type, yarn twist and fabric density. This information was important for the historic textile documentation, as well as for the comparative analysis (Figure2, block 1.2). Different techniques and data science tools were used for comparing and classifying textile fibres (Figure2, block 1.3). Optical microscopy was used to examine each sample in order to verify that the samples are homogeneous and do not contain any other fibre types (Figure2, block 1.3.1). The polymer type of the fibres was established by optical microscopy, SEM and FTIR-ATR (Figure2, blocks 1.3.1, 1.3.2, 1.3.3). The identification of the dye components present on the coloured fibres was performed by FTIR-ATR, SEM-EDS, HPLC and UV-Vis Spectroscopy, on both the solid samples and dye extracts (Figure2, blocks 2.1 and 2.2). The analysis provided data on the chemical composition of each dye present in the sample to confirm dye sources used as colorants on the investigated historical textile materials. Finally, a comparative analysis was applied to identify and match textile fabrics, yarns, fibres and dyes in order to confirm their authenticity and to establish common features (Figure2, block 3). Abbreviations: SEM, (Scanning electron microscope), FTIR-ATR (Fourier-transform infrared spectrometry with attenuated total reflectance), SEM-EDX (Scanning electron microscopy with an energy dispersive X-ray Spectroscopy), HPLC (High performance liquid chromatography).

2.2.1. Instrumentation and Software A preliminary examination using digital microscope Dino-Lite Pro AM 413T (1.3 megapixel image sensor, 10×−50×, 200× magnification, 8 White LEDs On/Off, USB 2.0 output and software Dino Capture 2.0. (Almere, The Netherlands) provided a quick, ac- curate and non-destructive method to characterise textile surface material (weave structure, thread count, surface damage). The polymer type of fibres was found by microscopic examination and infrared (IR) spectroscopy. Optical microscope analysis provided clear views of the morphology of the fibres. All fibre samples are examined with an Olympus BX40F4 microscope (ocular WH10x/22, objectives 10× and 40×) connecting to the computer via Olympus SC30 camera 3.3 MP (2048 × 1532 resolution, Olympus Europa SE & Co. KG, Hamburg, Germany) and software Stream Start (v1.5.1). Advantages of using scanning electron microscopy (SEM) were the ability to visually characterise fibres plus elemental analysis to identify mordant present in the samples. The samples were investigated using a TESCAN Scanning Electron Microscope (FE-SEM, MIRA\LMU, Czech Republic, program Mira TC, In-Flight Beam TracingTM, EasySEMTM, Wide Field OpticsTM) equipped with energy-dispersive spectroscopy (EDX with detector Quantax, Bruker SC7620-CF Mini AXS Microanalysis). FTIR spectroscopy (FTIR-ATR, PerkinElmer Spectrum 100) was applied to confirm whether the characteristic peaks for the suspected organic polymers were present in the spectra of the sample, using the spectra of known fibres as reference. FTIR-ATR was also used for identification of dye components present in colored fibres. FTIR-ATR of textile samples was traced in four scans at a resolution of 4 cm−1 in a wavelength range from 4000 to 400 cm−1 and software OMNIC Spectra Software 9.1.24. By using the same identical scan conditions to record both the fibre (reference) spectrum and the spectrum of the coloured sample, the intensity of the raw fibre spectrum was removed from the sample spectra by digital subtraction. Collected spectra were subtracted using Omnic 9.1.24 software, thus gaining a better understanding of the dye component. Materials 2021, 14, 4650 8 of 20

The chemical constituents of the extracted dye (Section 2.2.2) were identified through spectrophotometric and chromatographic analysis. The extracted dye was dissolved using water as solvent and scanned through UV-Visible spectrophotometer (Varian Cary® 50, Shimadzu Europe, Duisburg, Germany). The wavelength of the dye at lambda (k) max was measured and the compounds present in the extracts were interpreted. HPLC analysis of dyes were carried out using an Agilent 1200 series system (Agilent Technologies, Hewlett-Packard, Germany), including a diode array detector and the chromatographic system controlled by ChemStation software. HPLC conditions: C18 column 4.6 × 150 mm, 5 nm (4.6 × 150 mm and 5 µm particle size, ZORBAX Eclipse XDB, mobile phase A = 10% of methanol/water, v/v, B = 100% of methanol, gradient at start 16% B, at 15 min 90% B, at 23 min 100% B and 30 min 60% B, flow rate 0.5 mL/min, temp. 25 ◦C, injection vol. 10 mL, identification wavelength 254 nm. All reagents were analytical grade: methanol (HPLC-hipergradient grade), dimethylform-amide DMF (HPLC-gradient grade), formic acid (HPLC-gradient grade) from Merck, Germany. The method used to identify the dye was that of Jemo and Parac (2017). All additional data of the equipment used in this research are described in the Equip- ment catalogue of the University of Zagreb Faculty of Textile Technology [33]. Literature sources and online databases were used as a database of natural colours for FTIR analysis (IRUG-Infrared and Raman Spectral Database Users Group: Schweppe Collection, Getty Conservation Institute, [34]; SDBS-Spectral Database for Organic Com- pounds, [35]) and for HPLC analysis, (Eu-ARTECH Project-Analytical strategies for natural dyestuffs and cultural heritage objects, [30,32,36–50].

2.2.2. Extraction of Colorant The dye was extracted from both warp and weft textile samples (~0.002 g, fragments and original textile) using a solution of 5% Formic acid/MeOH at 100 ◦C for 10 min. Then, the solution was ﬁltered (Chromaﬁl PET-45/25, Macherey-Nagel, Düren, Germany) and a volume of 250 µL of the mixture MeOH; DMF (1:1, v/v) was added to the dry residue, then heated for 5 min at 100 ◦C. The extract obtained was used for UV-Vis i HPLC analysis.

3. Results and Discussions The starting point for making decisions in the textile conservation process to discover the materials present in any object is an examination [18]. It is equally important to analyse the original material, as well as the one added during a later time. Analytical techniques suitable for the analysis of cultural heritage are highly complex, and extremely small amounts of fibre sample are allowed to be taken from the carefully selected area. That is why the identification of textile materials was performed first, followed by the chemical composition of dyes, as shown in Figure2.

3.1. Identification of Textile Materials Analyses were carried out on warp and weft samples derived from the original textile fabric (Chasuble and Velum, Table1a,b), from fragments (Fragment 1 and 2, Table1c,d) as well as from sewing threads of old repairs (Table1e). Optical, scanning electron microscopy and FTIR-ATR analysis was used for fibre identification, while a Dino-Lite digital microscope with magnification: 10×−70×, 200× was used for weave and yarn characterisation.

3.1.1. Fibre Classification The surface morphology of all fibres was investigated using optical and scanning electron microscopy. It was found that analysed warp samples (Sample 1, 3, 5 and 7; Table1a–d ) correspond to the protein-based silk fibres (Bombyx mori, Figure3a), which have also been confirmed by FTIR-ATR analysis (Figure3b). Using OMNIC Spectra Software, the statistical discriminant analysis was performed determining that the similarity Materials 2021, 14, 4650 9 of 20

Materials 2021, 14, x FOR PEER REVIEWpercentage of the silk ﬁbre spectra from the database compared to each ﬁbre from10 theof 21 warp sample is around 70%.

0.22 SVIL A 0.20 Silk 0.18 0.16 0.14 0.12 0.10 Ab s or ba nc e 0.08 0.06 Materials 2021, 14, x FOR PEER REVIEW 0.04 10 of 21 0.02 0.20 2F_2x o 0.18 Sample 0.16 0.22 SVIL A 0.14 0.20 0.12 Silk 0.18 0.10 0.16 0.08 Ab s or ba nc e 0.14 0.06 0.12 0.04 0.10 0.02Ab s or ba nc e 0.08 0.00 0.06 400 0 350 0 300 0 250 0 200 0 150 0 100 0 500 0.04 Wav enumbers (cm-1) 0.02 (a) 0.20 2F_2x o (b) 0.18 Sample FigureFigure 3. Silk 3. Silk warp warp from from Fragment Fragment 2, Sample 2, Sample 7:( a7): ( SEMa) SEM photograph; 0.16 photograph; (b )(b FTIR-ATR) FTIR-ATR spectra spectra of of reference reference silk silk and and sample sample (red). (red). 0.14 0.12 It should be noted that 0.10 investigated samples contain other additives in the ﬁbre, 0.08

such as dyes, impurities,Ab s or ba ncmicroorganisms e and the products resulting from their metabolic activity, which caused a small 0.06 deviation from the uncoloured reference fibre. 0.04 On the other hand, 0.02all fibres from weft samples (Sample 2, 4, 6 and 8; Table1a–d) exhibited a distinctively flat0.00 “ribbon”, with a twist across the fiber length and a kidney- 400 0 350 0 300 0 250 0 200 0 150 0 100 0 500 shaped cross-sectional structure, all of which are characteristicWav enumbers (cm-1) of cellulosic seed fibres such (aas) cotton (Figure4a). Characteristic spectral bands( forb) cotton have also been confirmed Figure 3. Silk warp fromby Fragment FTIR-ATR 2, Sample spectroscopy 7: (a) SEM (Figurephotograph;4b), ( withb) FTIR-ATR the average spectra similarity of reference to silk the and reference sample cotton (red). fibre of 70%.

(a) (b) Figure 4. Cotton weft from Fragment 2, sample 8: (a) SEM photograph; (b) FTIR-ATR spectra of reference cotton and sample (red).

Due to their organic nature, textiles are among the most sensitive objects of cultural heritage and therefore over time become more fragile [9,17,18]. Damaged textile is often preserved adding repair patches or stitches, more or less successfully. Repair stitches recorded on the chasuble mutually differ. Sample 9 (red thread) proved to be mercerised cotton, while Sample 10 taken from the yellow thread was made of viscous fibre, based on morphological features and confirmed by IR microscopy with (a) (b) the average similarity to the reference fibre of 70%. FigureFigure 4. Cotton 4. Cotton weft fromweft from Fragment Fragment 2, sample 2, sample 8:(a 8): SEM (a) SEM photograph; photograph; (b) ( FTIR-ATRb) FTIR-ATR spectra spectra of referenceof reference cotton cotton and and sample sample (red). (red).

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Samples of warp and weft recorded by SEM and FTIR are given in Figures3 and4. Due to their organic nature, textiles are among the most sensitive objects of cultural heritage and therefore over time become more fragile [9,17,18]. Damaged textile is often preserved adding repair patches or stitches, more or less successfully. Repair stitches recorded on the chasuble mutually differ. Sample 9 (red thread) proved to be mercerised cotton, while Sample 10 taken from the yellow thread was made of viscous fibre, based on morphological features and confirmed by IR microscopy with the average similarity to the reference fibre of 70%.

3.1.2. Evaluation and Comparison of Fabrics Construction Parameters and Old Repairs Analysis of fabric construction parameters was carried out with the goal to show differences or conﬁrm similarities between discovered textile fragments hidden inside the chasuble and the original textile from the 19th century set of liturgical vestments from Dubrovnik, as shown in Table2.

Table 2. Fabrics construction parameters and ﬁbre classiﬁcation.

Fabric Density (Threads/cm) Fibre Identiﬁcation Material Type of Weave Warp * Weft ** Warp * Weft ** Classic damask in ﬁve-end satin, Chasuble 114 28 Silk Cotton (tal. Damasco classico) 1 Damask woven in combination of Velum eight-end satin and weft-faced 64 36 Silk Cotton twill (tal. Damasco di Lione) Damask woven in combination of Fragment 1 eight-end satin and weft-faced 64 36 Silk Cotton twill (tal. Damasco di Lione) Damask woven in combination of Fragment 2 eight-end satin and weft-faced 64 36 Silk Cotton twill (tal. Damasco di Lione) 1 The same fabric can be found on the maniple from the same set (Figure1c) [16]. * Samples: 1, 3, 5, 7. ** Samples: 2, 4, 6, 8.

Although all the warp samples (Sample 1, 3, 5 and 7) are classified as silk fibre and those from the weft (Sample 2, 4, 6 and 8) as cotton, some design and construction fabric parameters differ from each other (Table2). From Table2, it is evident that fragments from chasuble and damask from velum share common characteristics of weave pattern and yarn density, but not damask from the chasuble. Similarities in the samples of warp and weft taken from the textile fragments (Frag- ment 1 and 2) and damask from the chasuble are observed in colour tone (red tone), type of colorant (Table 4) and raw material composition (silk warp and cotton weft, Table2), as confirmed by the microscopic, spectroscopic and chromatographic analysis. Nevertheless, the design motive that is identical in both Fragment 1 and 2 differs from the original damask fabric of the chasuble. In addition, all other old repairs as interventive treatment on the chasuble that had significant impact on the historic textile over time were investigated and assessed. Par- ticularly interesting is the facts that on Fragment 2 (Table1d) there are identical repairs, made with the same thread and sewing techniques, as well as on lampas fabric (Table1e, Sample 9).

3.2. Chemical Composition of Dyes Extracted from Textile Samples Liturgical vestments from Dubrovnik date to the 19th century, the time when only natural dyes were used. Therefore, the presence of natural dyes, with the exception of subsequent interventions, is expected on all samples in this paper. Materials 2021, 14, 4650 11 of 20

Based on the available literature and historical and archaeological research, natural dyes of plant and animal origin, used in Dubrovnik and its surroundings, for dyeing red or purple are: kermes vermilio L., Caesalpinia echinata L., Rubia tinctorum L., Murex trunculus, Dactylopius coccus costa [45–50]. All samples taken from original textile fabrics (chasuble and velum) and from old Materials 2021,repairs 14, x FOR PEER (textile REVIEW fragments and sewing threads) were analysed for chemical and functional12 of 21

group identiﬁcation of their dye components and the presence of mordants. Most of the natural dyes are mordant dyes. A mordant is a metallic oxide, which, depending on the chemicalMost of the constitution, natural dyes are can mordant give differentdyes. A mordant hue colours is a metallic with oxide, the same which, dye. By using SEM-EDXdepending analysis, on the chemical it was possibleconstitution, to can determine give different various hue colours mordants with the insame coloured dye. By using SEM-EDX analysis, it was possible to determine various mordants in coloured samples. Figuresamples.5 shows Figure warp 5 shows and warp weft and samples weft sa frommples thefrom chasuble the chasuble damask damask fabric.

(a)

(b)

Figure 5. SEM-EDX analysis: (a) Sample 1;(b) Sample 2.

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Materials 2021, 14, 4650 12 of 20 Figure 5. SEM-EDX analysis: (a) Sample 1; (b) Sample 2.

AluminumAluminum detected on the silk warp warp samples samples ( Sample 1 , Figure Figure 55a;a; Sample 3, 5, 7 7)) may may indicate the presence of inorganic salt, called potassium aluminum sulfate (AlK(SO4)2), an indicate the presence of inorganic salt, called potassium aluminum sulfate (AlK(SO4)2), an importantimportant historic historic mordant mordant used used in in dyeing. dyeing. On On the the other other hand, hand, there there were were no elements thatthat could could be traced toto mordantsmordants onon thethe weftweft cotton cotton samples samples ( Sample(Sample 2 ,2 Figure, Figure5b; 5b;Sample Sample 4, 4,6, 6, 8) 8 as) as well well as as on onSample Sample 9 and9 and10 10. . TheThe FTIR-ATR technique diddid enableenable thethe comparisoncomparison of of different different samples samples and and charac- char- acterisationterisation of of the the polymer, polymer, but but gave gave incomplete incomplete information information on the on dyesthe dyes present present in coloured in col- ouredﬁbre. Infibre. order In order to enhance to enhance this information, this informatio Omnicn, Omnic 9.1.24 9.1.24 software software is used is used to subtract to subtract the thespectrum spectrum of the of characteristicthe characteristic uncoloured uncoloured reference reference ﬁbre from fibre the from spectrum the spectrum of the coloured of the colouredsample, thus sample, making thus it making easier for it someeasier individualfor some individual dye components dye components of coloured of samples coloured to samplesbe distinguished to be distinguished (Figure6). (Figure 6).

Figure 6. FTIR-ATR absorption spectra: 1-undyed sample sample of of reference reference silk fibre, ﬁbre, 2- Sample 1 ,, 3-dye spectrum obtained obtained by by spectral subtraction of reference silk spectraspectra from the coloured samplesample spectrum.spectrum.

ItIt can bebe statedstated thatthat all all FTIR-ATR FTIR-ATR samples samples spectra spectra from from the the chasuble chasuble highlight highlight absorp- ab- sorptiontion bands bands of 1710 of 1710 cm− cm1 to−1 to 1550 1550 cm cm−1−1in in which which intervals intervals are are detected: detected: conjugatedconjugated C=OC=O groups,groups, carbonyl carbonyl groups, groups, stretching of C-N bonds, stretching of C=C alkenes and amine N-HN-H stretch. stretch. Additionally, Additionally, absorbing absorbing bands bands of of 1450 1450 cm cm−1− to1 to600 600 cm cm−1 are−1 arecharacteristic characteristic for aromaticfor aromatic compounds, compounds, esters, esters, ethers, ethers, phenols, phenols, alcohols, alcohols, which which are otherwise are otherwise found found in nat- in uralnatural dye. dye. FTIR-ATRFTIR-ATR analysis of all all warp warp samples samples ( (SampleSample 1, 1, 3, 3, 5, 5, 7 7)) shows shows characteristic characteristic finger- ﬁnger- printprint spectral features of C=C bond bond stretchi stretching,ng, conjugated conjugated C=O C=O groups, groups, carbonyl carbonyl groups, groups, -OH groups groups in in the the region region of of 1100 1100 cm cm−1 −to1 1600to 1600 cm− cm1, which,−1, which, according according to the to spectral the spectral data- basedatabase (Section (Section 2.2.1.) 2.2.1 are) characteristic are characteristic functional functional groups groups found found in madder in madder root. root. OnOn the the other hand, all weft samples ( Sample 2, 4, 6, 8) havehave conjugatedconjugated C=OC=O groups − − − atat 1665 1665 cm cm−1 and1 and stretching stretching of aromatic of aromatic C=C C=C bond bond at 1584 at1584 cm−1 cmand 11467and cm 1467−1, all cm charac-1, all teristiccharacteristic of the Murex of the trunculusMurex trunculus used inused the Dubrovnik in the Dubrovnik area. In area.addition In addition to its two to smaller its two −1 −1 0 peakssmaller at peaks977 cm at−1 977and cm 947 cmand−1, 947this cmcan be, this attributed can be attributedto 6,6′-dibromoindigo. to 6,6 -dibromoindigo. −1 BothBoth warp warp and and weft weft samples samples exhibit exhibit strong strong peaks peaks in the in the region region of 1100 of 1100 cm−1 cm to 1700to −1 cm1700−1, cmcorresponding, corresponding to the stretching to the stretching vibratio vibrationn of the C=C of the bond, C=C conjugated bond, conjugated C=O groups, C=O carbonylgroups, carbonyl groups and groups -OH andgroups, -OH characteristic groups, characteristic for infrared for spectra infrared of spectra cochineal ofcochineal dye. The −1 sharpdye. The peaks sharp observed peaksobserved at 1700–800 at 1700–800 cm−1 for cmSamplefor 9Sample and Sample 9 and 10Sample are characteristic 10 are character- of syntheticistic of synthetic dyes (Figure dyes (Figure7). 7).

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Figure 7. FTIR-ATR absorption spectra: 1-Sample 9, 2-Sample 10. Figure 7. FTIR-ATR absorption spectra: 1-Sample 9, 2-Sample 10. Bearing in mind the fact that Sample 10 (viscose fibre) and Sample 9 (mercerized cotton) are made of fibres whose production started at the beginning of the last century, it can be Bearing in mind the fact that Sample 10 (viscose fibre) and Sample 9 (mercerized cot- concluded that these subsequent interventions occurred during the 20th century. ton) are made of fibres whose production started at the beginning of the last century, it Chemical characterisation of dyes extracted from warp and weft samples was per- can be concluded that these subsequent interventions occurred during the 20th century. formed through spectrophotometric and chromatographic measurements. Although UV- Chemical characterisation of dyes extracted from warp and weft samples was per- Vis absorption spectra from dye extract determine only the physical characteristics of the formed through spectrophotometric and chromatographic measurements. Although UV- dye, and achieved spectra can be interpreted at the level of qualitative information, identi- Vis absorption spectra from dye extract determine only the physical characteristics of the fication of the peaks produced in the sample extracts gave a good indication for further dye, and achieved spectra can be interpreted at the level of qualitative information, iden- analysis. It is important to note that UV-Vis spectra taken of the whole sample can contain sometification overlapping of the peaks data produced (if more than in the one sample dyeis extracts present), gave and a good therefore indication the absorption for further maximaanalysis. of It the is UV-Visimportant spectral to note profile that UV-Vis of the individual spectra taken dye moleculesof the whole is notsample always can clearly contain distinguished.some overlapping Nevertheless, data (if more it can than be concluded one dye thatis present), Vis spectra and oftherefore all silk warp the absorption samples aremaxima slightly of different, the UV-Vis but theyspectral all exhibit profile an of intense the individual absorption dye band molecules around 500–555is not always nm, thatclearly may distinguished. indicate their antraquinonNevertheless, origin it can (Figure be concluded7), as pointed that Vis by FTIR-ATRspectra of analysis.all silk warp samplesVis spectra are slightly of all cottondifferent, weft but samples they all show exhibit some an intense similarities absorption and intense band absorptionaround 500– bands555 nm, in the that region may aroundindicate 500–550 their antraquinon nm (Figure 8origin). (Figure 7), as pointed by FTIR-ATR analysis.According to the sample database of original components, the characteristic wave- lengthVis of maximumspectra of all absorption cotton weft (λ maxsamples) in the show range some of 540–555similarities nm and can intense be attributed absorption to pseudopurpurine,bands in the region purpurine around 500–550 and colour nm from (Figure the 8). sea snails in the Muricidae family, while λmax 510According nm can referto the to sample alizarin, database cochineal of or original kermes components, dye. the characteristic wave- lengthDifferences of maximum can be absorption observed in (λ themax) UV in the area. range While of the540–555 extract nm of can the be weft attributed cotton samples to pseu- (Figuredopurpurine,8) shows purpurineλmax at 275 and nm, colour the extract from of the warp sea samplessnails in (Figure the Muricidae9) shows family,λmax at while 265 nm λmax and510 two nm peakscan refer at 289 to nmalizarin, and 299cochineal nm, indicating or kermes that dye. it is a dye from another source. Differences can be observed in the UV area. While the extract of the weft cotton samples (Figure 8.) shows λmax at 275 nm, the extract of warp samples (Figure 9) shows λmax at 265 nm and two peaks at 289 nm and 299 nm, indicating that it is a dye from another source.

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Figure 8. UV-Vis absorption spectrum of cotton wefts: 1-Sample 6 (Fragment 1), 2-Sample 8 (Frag- Figure 8. UV-Vis absorption spectrum of cotton wefts: 1-Sample 6 (Fragment 1), 2-Sample 8 (Fragment 2), Figurement 8. 2), UV-Vis 3-Sample absorption 2 (Chasuble), spectrum 4-Sample of cotton 4 (Velum). wefts: 1-Sample 6 (Fragment 1), 2-Sample 8 (Frag- ment3-Sample 2), 3-Sample 2 (Chasuble), 2 (Chasuble), 4-Sample 4-Sample 4 (Velum). 4 (Velum).

FigureFigure 9. 9. UV-VisUV-Vis absorption absorption spectrum spectrum of of silk warps: 1-Sample 55 (Fragment(Fragment 1),1), 2-Sample 2-Sample 7 7 (Fragment (Fragment 2), Figure2),3-Sample 3-Sample 9. UV-Vis 1 (Chasuble),1 (Chasuble),absorption 4-Sample spectrum4-Sample 3 of (Velum).3 (Velum).silk warps: 1-Sample 5 (Fragment 1), 2-Sample 7 (Fragment 2), 3-Sample 1 (Chasuble), 4-Sample 3 (Velum).

AA peak peak of of yellow yellow orange orange tone tone λλmaxmax 415415 and and 495 495 nm nm characterises characterises SampleSample 9 9andand 1010 ofof thetheA subsequent subsequentpeak of yellow interventions interventions orange tone (Figure (Figure λmax 10). 41510). and 495 nm characterises Sample 9 and 10 of the subsequent interventions (Figure 10).

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FigureFigure 10. UV-Vis 10. UV-Vis absorption absorption spectra spectra of samples of samples from from subsequent subsequent sewing sewing interventions: interventions: 1-Sample 1-Sample 9, 9, 2-Sample2-Sample 10 (Velum) 10 (Velum)..

High-performanceHigh-performance liquid liquid chromatography chromatography (HPLC) (HPLC) was was used used to identify to identify detectable detectable tracestraces of dye of dye components components on onextracts extracts from from textile textile samples samples (Table (Table 3).3 ).

TableTable 3. Traces 3. Traces of ofdye dye components components on on extracts fromfrom textile textile samples samples determined determined by HPLCby HPLC chromatography. chromatography. High-Performance Liquid Chromatography SampleHigh-Performance Rt. Liquid Time (min)Chromatography Compound 26.84 alizarin Sample Rt. Time (min) 28.14Compound purpurin Sample 1 26.84 33alizarin pseudopurpurin or munjistin 28.14 18purpurin carminic acid 21 flavokermesic acid Sample 1 33 pseudopurpurin or munjistin 18 26.85carminic acid alizarine 28.15 purpurine Samples 3, 5, 7 21 33flavokermesic pseudopurpurin acid or munjistin 26.85 18alizarine carminic acid 28.15 21purpurine flavokermesic acid Samples 3, 33 28.2 pseudopurpurin or munjistin indigotin 5, 7 Samples 2, 4 18 29.40carminic acid indigorubin 21 33flavokermesic acid dibromindigo 18 carminic acid Samples 6, 8 28.2 indigotin Samples 2, 21 flavokermesic acid 29.40 indigorubin 4 33 dibromindigo SamplesResults 6, indicate that18 the most dominant identifiedcarminic colorants acid in Sample 1 (silk warp) are8 anthraquinones alizarin21 and purpurin. In addition,flavokermesic a peak at acid 33 min is attributed to pseudopurpurin or munjistin, all derived from the root cultures of Rubia tinctorum L. (TableResults3 , Figureindicate 11 ).that During the most the dyeingdominant process, identified alizarin colorants forms ain complex Sample 1 with (silk metal warp) ions aresuch anthraquinones as aluminium, alizarin which and is identifiedpurpurin. byIn SEM-EDXaddition, a analysispeak at (Figure33 min 5is). attributed However, to two more peaks were observed at lower retention times in the HPLC chromatogram: carminic pseudopurpurin or munjistin, all derived from the root cultures of Rubia tinctorum L. acid (rt = 18 min) and flavokermesic acid (rt = 21 min) (Table3, Figure 11). This result (Table 3, Figure 11). During the dyeing process, alizarin forms a complex with metal ions confirms that the dye used in the Sample 1 is the madder and cochineal dyes. such as aluminium, which is identified by SEM-EDX analysis (Figure 5). However, two more peaks were observed at lower retention times in the HPLC chromatogram: carminic acid (rt = 18 min) and flavokermesic acid (rt = 21 min) (Table 3, Figure 11). This result confirms that the dye used in the Sample 1 is the madder and cochineal dyes.

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purpurin munjistin flavokermesic acid alizarin

carminic acid

FigureFigure 11. HPLC 11. HPLCchromatograms chromatograms of silk of warps: silk warps: 1-Sample 1-Sample 1, from 1, fromchasuble, chasuble, 2-Sample 2-Sample 7, from 7, from Fragment Fragment 2 as 2 prior as prior interven- intervention, tion, 3-3-SampleSample 3 3fromfrom Velum. Velum.

HPLCHPLC chromatograms chromatograms provide provide similar similar values values for Sample for Sample 3 (silk3 warp(silk warpof the oforiginal the original damaskdamask fabric fabricof the ofVelum) the Velum) and Sample and Sample 7 (silk 7warp(silk from warp fragment from fragment 2). FTIR-ATR 2). FTIR-ATR analysis analysis revealedrevealed that those that thosesamples samples have identical have identical infrared infrared spectra spectra as well. as Based well. Basedon the on HPLC the HPLC peak, peak,areas for areas the for three the components three components of the ofmadder the madder dye are dye identified are identified as follows: as follows: alizarin alizarin (rt = 26.85(rt = min), 26.85 purpurin min), purpurin (rt = 28.15 (rt = min) 28.15 and min) pseudopurpurin and pseudopurpurin or munjistin or munjistin (rt = 33 (rt min). = 33 min). Additional retention times were also observed, such as ~18 min of carminic acid and Additional retention times were also observed, such as ~18 min of carminic acid and ~21 ~21 min of flavokermesic acid. HPLC results indicate that the dye used in these samples is min of flavokermesic acid. HPLC results indicate that the dye used in these samples is a a mixture of madder and cochineal dye. mixture of madder and cochineal dye. For weft cotton samples (Sample 2, 4, 6 and 8), the analytical method with a reducing For weft cotton samples (Sample 2, 4, 6 and 8), the analytical method with a reducing agent was used to prove the characteristic behaviour of indigoid dyes. Treatment with agent was used to prove the characteristic behaviour of indigoid dyes. Treatment with a a reducing agent yielded yellow-green “leuco indigo” form, which then changed to a reducing agent yielded yellow-green “leuco indigo” form, which then changed to a bluish bluish tone by the processes of oxidation. The major chromatographic peaks seen in those tone by the processes of oxidation. The major chromatographic peaks seen in those sam- samples showed characteristic retention times at 28.2 min of indigotin, at 29.40 min of ples showed characteristic retention times at 28.2 min of indigotin, at 29.40 min of indigo- indigorubin and at ~33 min of 6,60-dibromindigo, all characteristic for the Murex sea snail rubin and at ~33 min of 6,6′-dibromindigo, all characteristic for the Murex sea snail dye dye (Figure 12). The peak eluted at 18 min was marked as carminic acid and the peak at (Figure 12). The peak eluted at 18 min was marked as carminic acid and the peak at 21 21 min as flavokermesic acid (Figure 12). Based on the obtained result and data available min asin flavokermesic the literature, acid those (Figure compounds 12). Based indicate on the the obtained presence ofresult the cochinealand data available dye. Considering in the literature,the fact thatthose those compounds weft cotton indicate samples the containpresence all of chromophore the cochineal groups dye. Considering mentioned above, the factit that is confirmed those weft that cotton the extracted samples cont dyeain is a all mixture chromophore of dyes fromgroups and mentioned cochineal. above, it is confirmed that the extracted dye is a mixture of dyes from and cochineal. The results of dyestuff analysis of investigated samples are given in Table 4.

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6-6′-dibrom in- indigo indigorubin flavokermesic digo acid

carminic acid

FigureFigure 12. 12.HPLC HPLC chromatograms chromatograms ofof cottoncotton wefts: 1- 1-SampleSample 2 2, ,from from chasuble; chasuble; 2-Sample 2-Sample 8, 8from, from Fragment Fragment 2 as 2 prior as prior inter- intervention;vention; 3-Sample 3-Sample 4 from 4 from velum. velum.

TableThe 4. results Characterisation of dyestuff of dyes analysis of investigating of investigated samples. samples are given in Table4. Material Sample Identified Dyes Table 4. Characterisation of dyes of investigating samples. Chasuble Sample 1 Madder (Rubia tinctorum L.), Cochineal (Dactylopius coccus) MaterialSample 2 Tyrian purple Sample (Murex trunculus), Cochineal Identiﬁed (Dactylopius Dyes coccus) Velum Sample 3 MadderSample (Rubia 1 tinctorum L.), CochinealMadder (Rubia (Dactylopius tinctorum L.),coccus) Chasuble Sample 4 Tyrian purple (Murex trunculusCochineal), Cochineal (Dactylopius (Dactylopius coccus coccus) ) Fragment 1 Sample 5 MadderSample (Rubia 2 tinctorum L.),Tyrian Cochineal purple ( (DactylopiusMurex trunculus coccus), ) Cochineal (Dactylopius coccus) Sample 6 Tyrian purple (Murex trunculus), Cochineal (Dactylopius coccus) Sample 3 Madder (Rubia tinctorum L.), FragmentVelum 2 Sample 7 Madder (Rubia tinctorum L.), Cochineal (Dactylopius coccus) Cochineal (Dactylopius coccus) Sample 8 Tyrian purple (Murex trunculus), Cochineal (Dactylopius coccus) Sample 4 Tyrian purple (Murex trunculus), Old repairs Sample 9 SyntheticCochineal dye (Dactylopius coccus) with Sample 10 Sample 5 SyntheticMadder dye (Rubia tinctorum L.), Fragment 1 stitches Cochineal (Dactylopius coccus) Sample 6 Tyrian purple (Murex trunculus), 4. Conclusions Cochineal (Dactylopius coccus) Sample 7 Madder (Rubia tinctorum L.), AnalysisFragment shows 2 that textile fragments discovered inside the chasuble do not belong to the original item. However, they are identical to the Cochinealfabric that (Dactylopius the velum coccus is made) of, Sample 8 Tyrian purple (Murex trunculus), since they have the same fabric characteristics, the warpCochineal and weft (Dactylopius are composed coccus) of the same type of fibre and they are dyed with the same type of dyes (Tables 2 and 4). Sample 9 Synthetic dye Old repairsThe right with answer stitches to the question of how the textile fragments identical to the velum Sample 10 Synthetic dye fabric got inside the chasuble may be is that they come from another set of liturgical vestments that were destroyed over time and then, at one point, used to stabilise the damaged 4.parts Conclusions of the chasuble in question. AnalysisSubsequent shows repairs that textile of the fragments lampas fabric discovered on theinside chasuble the chasubleexecuted doin red not belongand yellow to thethread original are item. particularly However, interesting they are identical(Table 1e). to theThe fabricsame thattype the of velumred seam is madeis also of, found since in theyFragment have the 2 same(Table fabric 1d). characteristics,Although analysis the warpshowed and that weft the are Fragment composed 2 of fabric the same is identical type ofto ﬁbre the anddamask they from are dyed the velum, with the therefore same type of the of dyes same (Tables age, the2 and results4). of the analysis of the sewingThe rightthread answer cast a todifferent the question light on of those how therepairs. textile Based fragments on the identicaldiscovery to that the fibres velum are fabriccomposed got inside of mercerised the chasuble cotton may dyed be iswith that the they synthetic come fromdye (Table another 4), setit was of liturgical concluded vestmentsthat the thread that were used destroyed to make the over stitches time on and fragment then, at 2 one is of point, more usedrecent to date. stabilise the damagedGiven parts the of fact the that chasuble the stitching in question. thread and the type of stitches found on Fragment 2 areSubsequent identical to repairsthose from of the the lampas red part fabric of the on lampas the chasuble fabric executedof the chasuble, in red andit can yellow be con- threadcluded are that particularly the small, interesting partially damaged (Table1e). parts The sameof the typeoriginal of red textile, seam were is also used found as a in test Fragmentsample to 2 (Tabledetermine1d). Althoughthe most suitable analysis sewing showed techniques that the Fragment that were 2 to fabric be applied is identical for the

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to the damask from the velum, therefore of the same age, the results of the analysis of the sewing thread cast a different light on those repairs. Based on the discovery that fibres are composed of mercerised cotton dyed with the synthetic dye (Table4), it was concluded that the thread used to make the stitches on fragment 2 is of more recent date. Given the fact that the stitching thread and the type of stitches found on Fragment 2 are identical to those from the red part of the lampas fabric of the chasuble, it can be concluded that the small, partially damaged parts of the original textile, were used as a test sample to determine the most suitable sewing techniques that were to be applied for the repair of the entire chasuble. For an unknown reason, it was decided to attach the mentioned fragment onto the interlining fabric inside the chasuble in order to preserve it as evidence. In addition, a synthetic dye was identified on a yellow thread from seams, which in regular, thick stitches cover damaged areas on the IHS monogram on lampas fabric. This evidence confirms the original thesis that at one point in time the chasuble was separated into pieces in order to carry out its complete stabilisation, after which it was reassembled. All of the above may suggest that this is a case of repairing worn-out liturgical vestments by removing damaged materials and joining the remaining parts, possibly from two different sets, into one. This assumption is based on the fact that some materials from the chasuble can be found on a few of the other artefacts that make up the liturgical set. A case study of textile fragments hidden inside the 19th century chasuble from Dubrovnik emphasised the importance of the application of modern instrumentation methods in the textile conservation–restoration study. Forensic scientists often need to identify and match textile fibres using sophisticated scientific instrumentation. The same method was applied in this paper where the fibre evidence and dyes from the fragments were compared with those from the liturgical set. As assumed, natural dyes were confirmed in all samples from the historic textile, with the exception of subsequent interventions. The red tone silk warps were dyed with two different natural dyes: madder (Rubia tinctorum L.) and cochineal (Dactylopius coccus); the red tone cotton wefts were also a mixture of the two dyes, dyed with Tyrian purple (Murex trunculus) and cochineal (Dactylopius coccus). The dyes identified on the historical textiles largely correspond to the known dyes used at that time in the Dubrovnik area. The results of dyestuff analysis can serve as a basis in creating a database of dyes used in the objects from this area. That will help to better understand the history and origins of each textile artefact that is registered as cultural property under protection by the Ministry of Culture.

Author Contributions: Conceptualisation, D.P.-O. and D.J.; methodology, D.J. and D.P.-O.; validation, D.P.-O.; formal analysis, D.P.-O. and D.J.; investigation, D.J. and D.P.-O.; resources, D.J.; data curation, D.P.-O.; writing—original draft preparation, D.J.; writing—review and editing, D.J. and D.P.-O.; visualisation, D.J.; supervision, D.P.-O. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: We have chosen to exclude this statement. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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