A Physicochemical Examination of Blue Shades in Pottery: Rich, Deep and Endless
1
Faculty of Archaeology, Leiden University, Einsteinweg 2, 2333 CC Leiden, The Netherlands
2
Institute of Nanoscience and Nanotechnology “Demokritos” National Center for Scientific Research, Aghia Paraskevi, 15310 Athens, Greece
*
Author to whom correspondence should be addressed.
Colorants 2023, 2(2), 453-470; https://doi.org/10.3390/colorants2020021
Submission received: 28 February 2023
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Revised: 21 April 2023
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Accepted: 8 June 2023
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Published: 19 June 2023
Abstract
:This study attempts to take aspects of pottery technology into account while concentrating on the blue pigment and glaze recipes of various kinds of glazed pottery types; that is to say, Iznik ware, Kütahya ware, Miletus ware, glazed fritware, porcelain, polychrome glazed ware, and monochrome glazed ware were collected from a rescue excavation site within the Castle of Mytilene in Lesvos Island, Greece. The decoration, surface treatment, and production technology were investigated on the basis of 23 ceramic fragments that can be dated to the Turkish/Venetian period. The present study concerns the manufacture of glazed pottery, and in particular, colour recipes and issues of glaze technology. This study endeavoured to look into the specifics of the medieval colour recipes used on the glazed ceramics from Mytilene. This was accomplished by using an analytical process that took into account the compositional information of blue pigments, glazes, and slip coatings. The chemical analysis was conducted using scanning electron microscopy (SEM-EDS), Raman spectroscopy provided information about the compositional variation, and the optical examination via optical microscopy (OM) and scanning electron microscopy (SEM-EDS) yielded information about the sample stratigraphy of the examined ceramic sections. This investigation into glazed ceramics was able to define and reflect the key aspects of each society’s perception of colour through a large variety of colour and glaze recipes.
1. Introduction
The application of material analysis in the investigation of compositions and production technologies of archaeological glazed pottery has been a growing area of research during the past decade. This is because pottery has always been one of the primary fields in the study of archaeological material, seen from many different viewpoints (art history, economic, daily-life-related, etc.). Detailed chemical investigations of glazed pottery have not received much attention despite the growing interest in archaeological pottery techniques in recent years. Glaze composition and blue pigments from the Near and Far East have not been studied to their full potential yet, although some important studies have been published [1,2,3,4,5]. For this purpose, blue pigment recipes from 23 ceramic fragments collected within the Castle of Mytilene were investigated in this study (Table 1).
Mytilene, the capital city of the eastern Aegean island of Lesvos, is located on the island’s southeastern shore, 12 miles from the northeast coast of Western Turkey (Asia Minor). Mytilene was a prosperous Greek seaport connecting the East and West. Its geographical location is privileged since Mytilene is close to the west coast of the Gulf of Adramyttion (Hadramut) and, in the past, dominated the straits between Lesvos and Western Turkey (Asia Minor). During the Byzantine period, Lesvos was in relative proximity to great cities, such as Constantinople, Thessaloniki, Nicaea (later Iznik), Ephesus, Phocaea, etc., while also maintaining its commercial links with Egypt and the Near East, which dated back to ancient times. The history of Lesvos is completely interwoven with that of the Aegean Sea, and the Eastern Mediterranean in general [6].
The Castle of Mytilene in Lesvos lies on the northwest part of the island, extending from the north harbour of the town to the summit of the hill (Figure 1 and Figure 2). Τhe oldest confirmed phase of its construction was in the 6th century during the reign of Justinian I. After the Ottoman conquest of Lesvos in 1462, the Ottomans kept the castle (Kastro) for both defensive and residential use and preserved it until 1912. The castle was further strengthened with the addition of a new fortification wall outside the old one and, in 1501, they added the lower castle (Kato Kastro). During the final years of the Ottoman domination, the upper castle (Epano Kastro) was used as soldiers’ barracks; the middle castle, Mesaio Kastro, was used as a prison for those awaiting trial, while the Kato Kastro was inhabited by the Muslim population. After the liberation of the island, Epano Kastro was used as lodges for the Greek army, Mesaio Kastro was used as a residential area for poor Greeks, and Kato Kastro was inhabited by the poor Muslim population still remaining on the island until the official population exchange of 1924 [7].
The Ottoman period yielded a rich collection of different ceramic wares from the 16th to the 19th century. Finds from the 16th century include small quantities of Iznik ware and Italian Montelupo ware; from the 18th century are also imports of Chinese blue-on-white ceramics, which were copied by Ottoman workshops. Other imports from the late 18th to early 19th century include monochrome green glazed ware from Chios, Didymoteicho ware from Northern Greece, and a small quantity of Çanakkale ware from the Dardanelles [8,9,10,11]. It is likely, however, that well-known current centres of ceramic production of Lesvos, such as Mantamados and Agiassos, were active in the 19th century as well [11].
This paper focuses on the study of blue pigment and glaze recipes of 23 glazed ceramics collected from the Castle of Mytilene in Lesvos (Table 1, Figure 3). The study of decoration and iconography of these artifacts is significant because it attests to various sources of influence from the Middle East and the Mediterranean. As part of a larger investigation on the production processes used to create medieval ceramics, the compositional variance of the glazes and blue pigments was examined using scanning electron microscopy (SEM-EDS) and Raman spectroscopy. Additionally, OM and SEM-EDS were used to study the surface preparation, stratigraphy, and manufacturing methods. In this study, an attempt was made to define variant ways to approach colour and glazes through combining scientific approaches and archaeological evidence. The need for a greater understanding of colour mixing, colour application, and pattern development in relation to aesthetic perception was made evident. Therefore, chemistry, the chemical reaction of the glazes, and the decoration techniques of pottery were studied. These studies of glazed ceramics could lead to the discovery of crucial elements for understanding each pottery workshop’s sense of colour and culture in different regions.
The decoration and the colour palette of pottery have been a defining feature for each region throughout art history. Despite the great diversity in the use of colour between chronological periods, there are some surprisingly stable and unifying features in the decoration of pottery artifacts. For example, pottery artists’ palettes around the Aegean seem to be focused on the blue-turquoise range of the spectrum through geometric designs or free style lines, plants, or vegetal motifs. Here, the impact of the landscape of each region on the aesthetic preferences of the potters, and in this case the inspiration from the Aegean Sea, is obvious. Furthermore, different shades of blue were also preferred in Islam as turquoise and cobalt are considered symbolic of the earth and sky (with heaven being akin to the sky). Moreover, the colour blue symbolises immortality and advancement in Chinese culture. The predilection for blue and turquoise colours as well as for complex blue colour composition was proven by the many different blue recipes that were analysed.
2. Materials and Methods
The 23 glazed ceramic fragments were studied under a stereo microscope, focusing on the stratigraphy of the layers and specifically on the description of colours, glazes, and slip coating structure. Additionally, 18 samples were taken from the selected fragments for the preparation and investigation of cross sections through a binocular polarising microscope. The sections were polished with a 0.25 mm diamond paste, embedded in polyester resin, and then covered in a coating of carbon. Another aspect of this optical examination was the microstructure of the glaze and slip coating, in terms of characteristics such as homogeneity, inclusions, and porosity. They were then investigated through the use of a Quanta Inspect D8334 SEM-EDS FEI. In order to obtain the best excitation of the low-energy and low-concentration elements, spectra with a lifetime of 100 s were taken while the EDS was a working voltage of 25 kV. Τhe beam diameter was 5 μm, the take-off angle 35°, and the dead time 15–20%. The type of detector was E-T, BS, LFD (low vacuum), EDX (light elements down to B), CCD IR inspection camera. The EDS spectra were calibrated using a cobalt standard and deconvoluted with the phi-rho-z correction procedure using the Oxford Instruments SEM Quant software, and the correction method was ZAF. The ZAF-corrected standardless EDS evaluation provides the oxide contents in wt% with a precision of 0.01 wt% (100 ppm). Analytical totals, which normally fall between 95 and 99%, were scaled to 100%. EDS was used to analyse the elemental compositions of the cross sections of the polished samples. Concentrations are shown as the average of three to five measurements taken in carefully chosen zones within the regions of interest, avoiding heterogeneity and body interfaces.
Although around 50 measurements were implemented using Raman spectroscopy analysis in the blue pigments of the glazed pottery under study, only 18 of them were interpreted due to the fluorescence of the glazes. Firstly, the Raman spectroscopy was performed with a Jobin-Yvon LabRam HR 800 system, and a green laser with a 532 nm diode laser and 2 μm spot diameter was used in the Institute of Nanoscience and Nanotechnology at the National Research Center “NCRS Demokritos” in Greece. Subsequently, due to high fluorescence, another Raman instrument was used—specifically, the DeltaNu RockHound handheld Raman Spectrometer in the Laboratory of Ion Beam and Raman Spectroscopy at the University of West Attica. It has a near-infrared 785 nm diode laser in order to minimize the fluorescence of the organic medium. The resolution is 8 cm−1 and the spectra were acquired in the wavenumber range of 200 cm−1 up to 2000 cm−1. Only the blue pigments of the samples MYT168 and MYT170 were studied with the Jobin-Yvon LabRam HR 800 Raman instrument and the rest of the blue pigments were studied with the DeltaNu RockHound Raman instrument. Micro-Raman spectroscopy was used to analyse ceramic pigments with various characteristics and technological backgrounds. In particular, Raman scattering experiments were carried out on the painted ceramics’ surface to examine the pigments already present. As long as the fragments were tiny enough to be moved beneath the laser probe and evaluated in their entirety without further handling, Raman spectroscopy did not require sample preparation. Raman spectroscopy identified the chemical components of the pigments and yielded complementary information in combination with Scanning electron microscopy (SEM-EDS).
3. Results
The decoration of the 23 glazed ceramic fragments consisted of geometric designs or free style lines, plants, or vegetal motifs. The remaining fragments represented monochrome glazed wares. In general, the pottery which came from Mytilene had a variety of colours—among which were green, brown, and yellow, but the most common one was blue—on which the selection of samples was based.
According to scanning electron microscopy (SEM-EDS), four blue-colour recipes were noticed in the fragments of polychrome painted ware, Kütahya ware, Iznik ware, porcelain, Miletus ware, and glazed fritware. The first blue-colour recipe with CoO was observed in samples of polychrome painted ware (MYT215), Kütahya ware (MYT241), Iznik ware (MYT168, MYT170), and porcelain (MYT223). Finally, one Iznik ware sample (MYT170) contained SnO2 due to its existence in the glaze. The second blue-colour recipe was the combination of CoO and CuO, observed in samples of Kütahya ware (MYT184, MYT188, and MYT242), glazed fritware (MYT182), and Miletus ware (MYT167). Furthermore, a Miletus ware sample (MYT167) contained CoO, CuO, and NiO. A Kütahya ware sample (MYT184) contained SnO2 due to its existence in the glaze. Finally, one Kütahya ware sample (MYT242) as well one Miletus ware (MYT167) sample contained NiO. The third blue-colour recipe was detected in a sample of porcelain (MYT221) that contained CoO and MnO in low percentages for a light-blue colour or in another porcelain sample (MYT185) that contained CoO and MnO in higher percentages for a dark, purplish-blue colour. The fourth blue-colour recipe was observed in an Iznik ware sample (MYT214) with CuO for a light blue without CoO. The existence of SnO2 in this sample was probably intentional due to the higher percentage of SnO2 (up to 1.7%) than the glaze. Potentially, the potters tried to create a whitish light blue (Table 2, Figure 4 and Figure 5) [12,13].
Two turquoise-colour recipes were studied as well. The first turquoise recipe was observed in a Kütahya ware (MYT179) and monochrome glazed ware sample (MYT200). The colorant of the turquoise colours of Kütahya ware (MYT179) and of monochrome glazed ware (MYT200) was CuO. Both used the same recipe, but the turquoise colour of the monochrome glazed Ware sample (MYT200) also contained TiO and ZnO, and as a result, this colour had a more intense hue than sample MYT179. The second recipe was a Kütahya ware sample (MYT230) with CuO and CoO (Table 2, Figure 5 and Figure 6) [12,13].
Dark blue lines were produced from five different recipes. Within the first recipe, the colorants of the dark blue line of two Kütahya ware samples (MYT188 and MYT179) were Fe2O3, MnO, CuO, and Cr2O3. The second recipe was used for the dark line of a Kütahya ware sample (MYT230) with Fe2O3, CuO, Cr2O3, and CoO. In the third recipe, the dark line of the Iznik ware sample MYT170 was due to Fe2O3, CoO, and Cr2O3. The fourth recipe of the dark blue line of one polychrome painted ware sample (MYT215) had CoO, MnO, Cr2O3, and Fe2O3, and finally, the fifth one was observed in a Miletus ware sample (MYT167) that had CoO, Fe2O3, Cr2O3, NiO, and Zn (Table 2) [12,13]. With a higher Cu content in the blue-colour recipe, a more greenish-blue hue is produced; with a higher Co content, a deeper blue hue is produced; with a higher Cr content, a darker greenish-blue hue (green colour with Cr3+) or black-blue hue (black colour with Cr6+) is produced; and with a higher Mn content, a more brownish blue hue is produced [14]. On the other hand, with a higher Co content in the turquoise-colour recipe, a more turquoise-to-blue hue is produced; with a higher Fe content, a darker turquoise hue is produced (Figure 4 and Figure 6).
According to scanning electron microscopy (SEM-EDS), three different glaze recipes were observed. The first glaze recipe was a lead alkali glaze recipe that was observed in the fragments of Kütahya ware (MYT179, MYT184, MYT188, and MYT242), Iznik ware (MYT168, MYT170, and MYT214) and glazed fritware (MYT182) which contained PbO (18.1–24.2%), NaO2 (5.7–6.5%), CaO (1.4–2.8%), and K2O (0.6–1.7%). The Iznik ware contained SnO2 as well. The second glaze recipe was an alkali glaze recipe that was observed in the samples of porcelain (MYT185, MYT186, MYT221, and MYT223) and monochrome glazed ware (MYT200), which contained CaO (2.9–6.6%), NaO2 (2.1–3.7%), and K2O (0.8–2.6%). The third glaze recipe was a lead alkali glaze with a high soda percentage that was observed in the fragments of polychrome painted ware (MYT215) and Miletus ware (MYT167 and MYT204), which contained PbO (13.6–26.2%), NaO2 (7.3–11%), K2O (0.9–1.1%), and CaO (0.6–0.9%) (Table 3) [13,14]. The glaze of samples MYT230 and MYT241 was not analysed as all their surface was covered in a blue colour.
The potters who manufactured the pottery under study were experienced in glossy or matte glazes so that the desired result could be achieved. According to Wolf Matthes 1985, the addition of tin oxide (SnO2) offers opacity due to its insolubility, as was observed in some fragments of Iznik (MYT168, MYT170, and MYT214) and Kütahya wares (MYT184); zinc oxide (ZnO) increases the brightness of glasses in small quantities and, in combination with Al2O3, increases the coverage and brightness of enamels, as was observed in some fragments of Miletus (MYT167) and monochrome glazed wares (MYT200); nickel oxide (NiO) gives bright colours, as was observed in some fragments of Miletus (MYT167), Kütahya (MYT242), and polychrome glazed wares (MYT215); and titanium dioxide (TiO2) gives whiteness and opacity in glazes, as was observed in some fragments of monochrome glazed wares (MYT200) and porcelain wares (MYT221) (Table 3) [15].
The slip coatings of polychrome painted ware, Kütahya ware, and Iznik ware were quite similar and they consist of NaO2, MgO, Al2O3, SiO2, K2O, CaO, and Fe2O3. The measured compositions of each layer were quite similar and no significant differences among the samples were observed apart from the Miletus ware samples and the monochrome glazed ware sample MYT200. The Miletus ware slip coatings contained NaO2, MgO, Al2O3, SiO2, K2O, CaO, and Fe2O3. The slip coatings of the Miletus ware contained higher Al and lower Si levels than the above-mentioned slip coatings. The chemical composition of the slip coating of monochrome glazed sample (MYT200) was very different from the usual slip coatings. The slip coating of the MYT200 sample contained NaO2, Al2O3, SiO2, CaO, Fe2O3, ZnO, and TiO2 with a high amount of ZnO and TiO2 but no K2O. The percentage of SO3 is due to the interference of Pb lines in S Ka lines. The presence of Fe and Mg (part of them), Co, Cu, Ti, Zn, Sn, and Pb is due to the interference of glaze and pigments (Table 4) [13,14].
The slip coating had various functions in pottery construction and in the decoration of the ceramics under study. Separate slip coatings below the glaze were observed in fragments of all ware types with glaze diffusing into the slip coatings (the presence of Co, Cu, Sn, and Pb), apart from the porcelain and glazed fritware that did not have a slip coating because they consisted of white fabric. The slip coatings, the entire surface of which was coloured with metal oxides, were not analysed. The slip coatings were more compact and vitrified. The optical microscopy images suggested that the thicknesses of the surface layers were not uniform, and they ranged from about 100 to 600 µm. Slip coatings were observed not only on wide open surfaces but also on inner curved surfaces. These data clearly indicate that a fine slip coating, with or without colorant and more fluxes, was used in the production of the slip coating. The iron content of the slip coating was typically low.
Regarding the decoration, the motifs were designed on the slip coating and the pigment oxides were added in the glaze for monochrome glazed ware, glazed fritware, and porcelain. In all the other pottery typologies (Kütahya ware, Iznik ware, Miletus ware, and polychrome glazed ware), pigments were added on the slip coating. All of them had underglaze decoration (Figure 7).
According to Raman spectroscopy, the blue colour of the Kütahya ware samples MYT169, MYT179, MYT242, and MYT230; the Miletus ware sample MYT204; and the Iznik ware sample MYT214 came from lazurite oxide Na8[Al6Si6O24]Sn. The blue colour of the Miletus ware sample MYT167; the Iznik ware sample MYT170; the polychrome painted ware samples MYT215 and MYT228; the porcelain sample MYT221; and the Kütahya ware samples MYT241 and MYT184 came from blue smalt, CoO·nSiO2 [16,17,18,19,20,21]. The blue colour of the Iznik ware sample MYT168 came from Egyptian blue calcium copper (II) silicate CaCuSi4O10. Theophrastus, in his book De Lapidibus, stated, “Just as there is a natural and an artificial ruddle, so too there is a natural and a prepared cyanus, such as is made in Egypt. There are three kinds of cyanus, the Egyptian (CaCuSi4O10 or CaO·CuO·4SiO2), the Scythian, and lastly the Cyprian, the Egyptian being best for undiluted pigment-powders” [22], p.79. The blue colour of the porcelain sample MYT185 came from cobalt blue CoO·Al2O3 [16,17,18,19,20,21,23,24,25,26]. The turquoise colour of the monochrome glazed ware sample MYT200 was due to Cu in Pb with a high amount of alkalis. The reaction of Cu with the fluxes produced the turquoise colour [23,27,28,29]. The blue colour of the glazed fritware sample MYT182 and the Kütahya ware sample MYT188 came from Azurite 2CuCO3·Cu(OH)2 (Table 5) [10,11,12,16,17,23,24].
4. Discussion
The history of Lesvos is completely interwoven with that of the Aegean Sea and the Eastern Mediterranean in general. Mytilene was a prosperous seaport connecting the East and West [7]. During the medieval period, the island retained its commercial links with Egypt and the Near East, which dated back to ancient times; these ties were maintained and even strengthened under Ottoman rule (1462–1912), since all regions formed part of the Ottoman Empire. Although the Ottoman period yielded a rich collection of different imported ceramics that were manifested in different pottery workshops in Asia Minor and in the Near East and were found within the Castle of Mytilene (such as polychrome marbled ware, Iznik ware, Kütahya ware, glazed white ware, Miletus ware, painted ware, polychrome sgraffito ware, elaborate incised ware, Zeuxippus ware, and Roulette/Veneto Ware), there is some evidence of local pottery activity in Early and Middle Byzantine times in Lesvos. Multicultural art flourished and ceramics played a role in colour and pattern development in that era. A broad palette of colours was developed and the most dominant colour was blue and its different hues; many glaze recipes and patterns were also created in that era. A potter approaches the colour blue firstly from a technical aspect: the colours of the clay, slip coatings, oxides, etc., and the effects that can be achieved with different glazes alone or in combination; secondly, there is also evidence of the aesthetic perception of the colour blue. The high diversity of pigments in the collection under study gathered from Mytilene was remarkable. Four blue-colour recipes were noticed, specifically, the first one with Co; the second one with Co and Cu; the third one with Co and Mn; and the fourth one with Cu. Two turquoise-colour recipes were noticed, specifically, the first turquoise recipe with Cu and the second one with Cu and Co. Finally, in the dark blue lines, five colour recipes were observed: the first recipe with Fe, Mn, Cu, and Cr; the second one with Fe, Cu, Cr, and Co; the third one with Fe, Co, and Cr; the fourth one with Co, Mn, Cr, and Fe; and the fifth one with Co, Fe, Cr, Ni, and Zn. For the dark colours, the main colorant was at a higher proportion than the light colours. The presence of iron was also observed in the blue pigment analyses. In general, the Fe2+/Fe3+ present in the glaze ratio was determined by the atmosphere and firing temperature: the higher the temperature, the higher the ratio. As iron is the most prevalent impurity found in rocks, it is frequently impossible to completely remove it from the glaze because it can be absorbed into the structure of most clay minerals. The primary method of avoiding the iron colouring effect is the selection of naturally low-iron materials [4,30]. Further analyses need to be carried out in the future in order to support the premise that the presence of iron is caused by structural minerals or by deliberate addition [4].
According to Raman spectroscopy, the blue colours of the Kütahya samples, Miletus samples, and Iznik samples came from lazurite oxide or from blue smalt. Similarly, the blue colours of the polychrome painted ware samples and porcelain samples came from blue smalt. Two more different blue colours were detected and in particular blue colour at Iznik ware sample which came from Egyptian blue calcium copper (II) silicate; and this at porcelain sample which came from cobalt blue. The turquoise colour of the monochrome glazed ware sample was due to Cu in Pb with a high amount of alkalis [23,27,28,29]. The blue colour of the glazed fritware sample and the Kütahya ware sample came from azurite.
Furthermore, three different glaze recipes were observed. The first glaze recipe was a lead alkali glaze recipe that was observed in the fragments of Kütahya ware, Iznik ware, and glazed fritware. The second glaze recipe was an alkali glaze recipe that was observed in the fragments of porcelain and monochrome glazed ware, and the third glaze recipe was a lead alkali glaze with high a soda amount that was observed in the fragments of polychrome painted ware and Miletus ware. It was demonstrated that the potters who made the ceramics under study had gained the knowledge of how to produce glossy, matte, bright, white, or opaque glazes to achieve the intended result.
For bright glaze colours, the potters had the knowledge that the underlying fabric should be white, or a slip coating needed to be applied on it in order to have a good reflectivity. The measured chemical compositions of the slip coatings of polychrome painted ware, Kütahya ware, and Iznik ware were quite similar and no significant differences among the samples were observed, apart from the Miletus ware samples that contained higher Al and lower Si levels and the monochrome glazed ware sample MYT200 that contained a high amount of Zn and Ti. A possible interpretation is that the slip coating of this ceramic is not a natural, but rather a handmade, mix [23,24]. The optical microscopic images of the slip coating obtained from all samples indicated that a very compact and uniform vitrified structure formed over the vessels apart from the porcelain and glazed fritware. To sum up, regarding the decoration, the motifs were designed on the slip coating and the pigment oxides were added in the glaze for the monochrome glazed ware, glazed fritware, and porcelain. In all the other pottery typologies, the pigments were added on the slip coating with a brush or similar tool. All of them were decorated with underglaze decoration.
5. Conclusions
The potters of the Iznik and Kütahya regions, located in Western Turkey, used the same type of glaze, namely “lead alkali glaze” sometimes with the addition of Sn; however, they used different blue-colour recipes. The potters from Iznik used only one colorant, i.e., Co or Cu, in contrast to the potters of Kütahya who produced blue colours, turquoise colours, and dark blue outlines based on mixing two or three colorants for the desired blue shades. At the pottery workshops of Miletus, despite being geographically adjacent to the other two pottery workshops, a different glaze recipe (“lead alkali glaze with high Na”), blue-colour recipes, and dark-blue-line recipes were used. In conclusion, although Iznik and Kütahya pottery workshops shared common technological glaze practices, the Kütahya pottery workshops apparently experimented more with different blue-colour recipes compared to the Iznik pottery workshops. On the other hand, the Miletus pottery workshops created their own technological glaze and colour recipes. In the polychrome glazed ware, the same glaze composition was observed as the Miletus wares—lead alkali glaze with high Na—while the monochrome glazed ware had an alkali glaze. Their blue colours were rather common and simple recipes with Co and the turquoise colours with Cu. The glazed fritware had a lead alkali glaze and its blue colour resulted from the combination of Co and Cu. According to archaeological evidence, the latter-mentioned three fragments came from the Near East in the Turkish/Venetian period, but their exact location remains unknown. Finally, the pottery workshops in China used alkali glazes with Co based blue pigments for the manufacture of porcelain.
In the case of blue colour, the presence of Cu causes a greenish-blue hue; the presence of Co causes deeper blue hue; the presence of Cr causes a darker greenish-blue hue or a black-blue hue; and the presence of Mn causes a brownish/purplish-blue hue. In the case of turquoise colour, the presence of Co causes a blue hue. Furthermore, different glaze recipes were used due to the existence of tin oxide (SnO2), zinc oxide (ZnO), nickel oxide (NiO), and titanium dioxide (TiO2) in view of transparency, opacity, whiteness, or brightness. Through a broad range of glazes, underglazes, and on-glaze decorations, a larger palette of blue colours could be achieved, allowing for depicting a wide range of designs. Nevertheless, the present case study includes only a small part of the glazed wares circulating in the Eastern Aegean during the Ottoman Period. Future studies investigating other colour shades and their relation to the addition and combination of transition metals in various valence states, for example through reflection spectroscopy, are expected to provide additional information [4].
Author Contributions
Conceptualization, A.P.P.; methodology, A.P.P., A.H. and V.K.; software, A.P.P. and A.H.; validation, A.H., V.K. and J.V.; formal analysis, A.P.P.; investigation, A.P.P.; resources, V.K.; data curation, A.P.P. and A.H.; writing—original draft preparation, A.P.P.; writing—review and editing, J.V. and A.H.; visualization, A.P.P.; supervision, A.H., V.K. and J.V.; project administration, A.H.; funding acquisition, J.V. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by Prins Bernhard Cultuurfonds, grant number: 40032864.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Acknowledgments
I would like to thank Pavlos Triandafillidis at the Ephorate of Antiquities of Lesvos, for his permission to sample and study the ceramics in this research. Furthermore, I would like to thank Theodore Ganetsos at the University of West Attica, Nondestructive Techniques Laboratory. Finally, I would like to thank Nikos Laskaris at the University of West Attica.
Conflicts of Interest
The authors declare no conflict of interest.
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Figure 1.
The Castle of Mytilene in Lesvos, Greece [2] (p. 15).
Figure 1.
The Castle of Mytilene in Lesvos, Greece [2] (p. 15).
Figure 2.
Map of the Castle of Mytilene in Lesvos [6] (p. 107).
Figure 2.
Map of the Castle of Mytilene in Lesvos [6] (p. 107).
Figure 3.
The ceramic fragments under study from the Castle of Mytilene in Lesvos. The arrows present the blue pigments that were analysed.
Figure 3.
The ceramic fragments under study from the Castle of Mytilene in Lesvos. The arrows present the blue pigments that were analysed.
Figure 4.
Blue pigments/colour and dark blue line pigments. The existence of Cu leads to greenish-blue hue; the existence of Co leads to deeper blue hue; the existence of Cr leads to darker greenish-blue hue lines or black-blue hue lines; the existence of Mn leads to brownish/purplish-blue hue. Graphs of the pottery samples collected from the Castle of Mytilene in Lesvos.
Figure 4.
Blue pigments/colour and dark blue line pigments. The existence of Cu leads to greenish-blue hue; the existence of Co leads to deeper blue hue; the existence of Cr leads to darker greenish-blue hue lines or black-blue hue lines; the existence of Mn leads to brownish/purplish-blue hue. Graphs of the pottery samples collected from the Castle of Mytilene in Lesvos.
Figure 5.
Blue/turquoise pigments under optical microscopy and scanning electron microscopy. The arrows indicate the point of analysis.
Figure 5.
Blue/turquoise pigments under optical microscopy and scanning electron microscopy. The arrows indicate the point of analysis.
Figure 6.
Turquoise pigments. Graphs of the pottery samples collected from the Castle of Mytilene in Lesvos. The existence of Cu leads to turquoise hue; the existence of Co leads to bluish turquoise hue.
Figure 6.
Turquoise pigments. Graphs of the pottery samples collected from the Castle of Mytilene in Lesvos. The existence of Cu leads to turquoise hue; the existence of Co leads to bluish turquoise hue.
Figure 7.
Underglaze decoration of the fragments under study.
Table 1.
The pottery typology of the 23 studied samples from the Castle of Mytilene in Lesvos.
| Pottery Typology | Date | Code | Number |
|---|---|---|---|
| Iznik ware | 15–18th c. | MYT168, MYT170, MYT214 | 3 |
| Kütahya ware | 15–18th c. | MYT169, MYT179, MYT184, MYT188, MYT230, MYT241, MYT242 | 7 |
| Miletus ware | 15–18th c. | MYT167, MYT204 | 2 |
| Glazed fritware | 15–18th c. | MYT182 | 1 |
| Porcelain | 15–18th c. | MYT185, MYT186, MYT221, MYT223 | 4 |
| Monochrome glazed ware | 15–18th c. | MYT173, MYT174, MYT200, MYT220 | 4 |
| Polychrome painted ware | 15–18th c. | MYT215, MYT228 | 2 |
Table 2.
Scanning electron microscopy analysis of the blue pigments in the sampled pottery collection from the Castle of Mytilene in Lesvos (%); nd = non detective.
Table 2.
Scanning electron microscopy analysis of the blue pigments in the sampled pottery collection from the Castle of Mytilene in Lesvos (%); nd = non detective.
| Samples | Na2O | MgO | Al2O3 | SiO2 | P2O5 | SO3 | Cl2O | K2O | CaO | TiO2 | Cr2O3 | MnO | Fe2O3 | CoO | NiO | CuO | ZnO | SnO2 | PbO | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| BLUE | ||||||||||||||||||||
| Polychrome painted ware | MYT215 | 11.8 | 0.8 | 1.1 | 56.3 | nd | 11.6 | 0.8 | 0.9 | 1.1 | nd | nd | 0.0 | 0.5 | 0.4 | nd | nd | nd | nd | 14.8 |
| Kütahya ware | MYT241 | 9.1 | 1.5 | 1.2 | 50 | nd | 11.9 | 1.1 | 2.5 | 2.6 | nd | nd | nd | 1.04 | 0.5 | nd | nd | nd | nd | 18.5 |
| Iznik ware | MYT168 | 4.1 | 0.5 | 1.1 | 77.3 | nd | 5.5 | 0.5 | 1.9 | 26.2 | nd | nd | nd | 0.9 | 0.6 | nd | nd | nd | nd | 8.1 |
| Iznik ware | MYT170 | 7.8 | 1 | 1.1 | 44.7 | nd | 15.5 | nd | 0.7 | 0.9 | nd | nd | nd | 0.8 | 0.6 | nd | nd | nd | 2.2 | 24.7 |
| Porcelain | MYT223 | 0.5 | 0.4 | 16.1 | 73 | nd | nd | nd | 3.2 | 3.9 | nd | nd | nd | 1.2 | 1.4 | 0.5 | nd | nd | nd | nd |
| Porcelain | MYT223 | 0.4 | 0.2 | 20.9 | 69.9 | nd | nd | nd | 3.2 | 4.1 | nd | nd | nd | 0.7 | 0.5 | 0.2 | nd | nd | nd | nd |
| Kütahya ware | MYT184 | 1.5 | 0.8 | 3.03 | 36.8 | nd | 17.3 | 1 | 3.8 | 3.1 | nd | nd | nd | 2.1 | 0.3 | nd | 1.01 | nd | 4.8 | 24.6 |
| Kütahya ware | MYT188 | 7.3 | nd | 3.1 | 52.6 | nd | 13.4 | nd | 2.01 | 1.9 | nd | nd | nd | nd | nd | nd | 2.04 | nd | nd | 16.8 |
| Kütahya ware | MYT242 | 8.2 | 1.2 | 1.3 | 52.5 | nd | 9.8 | 1.1 | 1.1 | 2.6 | nd | nd | 0.3 | 0.7 | 0.3 | 0.26 | 0.3 | nd | nd | 20.8 |
| Glazed fritware | MYT182 | 2.3 | 0.4 | 2 | 78.1 | nd | 5.04 | 0.5 | 1.5 | 1.3 | nd | nd | nd | 1 | 0.3 | nd | 0.3 | nd | nd | 7.1 |
| Miletus ware | MYT167 | 8.8 | 0.7 | 1.7 | 47 | nd | 11.6 | 0.8 | 1.3 | 0.8 | nd | nd | nd | 5.8 | 1.6 | 2.83 | 1.3 | nd | nd | 15.2 |
| Porcelain | MYT221 | 9.04 | 2.4 | 3.9 | 76.7 | nd | nd | 0.4 | 1.1 | 4.7 | 0.2 | nd | 0.3 | 1.02 | 0.2 | 0.1 | nd | nd | nd | nd |
| Porcelain | MYT185 | 1.3 | 6.3 | 15.1 | 68.2 | nd | nd | nd | 2.8 | 8.0 | nd | nd | 2.3 | 1.2 | 0.5 | nd | nd | nd | nd | nd |
| Iznik ware | MYT214 | 9.3 | 0.3 | 0.8 | 48.6 | nd | 15 | 0.8 | 0.8 | 0.6 | nd | nd | nd | 0.4 | nd | nd | 0.2 | nd | 2.8 | 20.4 |
| TURQUOISE | ||||||||||||||||||||
| Monochrome glazed ware | MYT200 | 4.1 | nd | 2.6 | 6.5 | nd | 11.9 | 1 | 0.6 | 4.1 | 57.4 | nd | nd | 5.4 | nd | nd | 1.4 | 4.9 | nd | nd |
| Kütahya ware | MYT179 | 10.8 | 0.8 | 1.1 | 59.6 | nd | 7.1 | 0.7 | 1.3 | 2.2 | nd | nd | nd | 0.5 | nd | nd | 0.9 | nd | nd | 14.9 |
| Kütahya ware | MYT230 | 7.7 | 0.5 | 1.7 | 55.7 | nd | 10.5 | nd | 1.3 | 2.1 | nd | nd | nd | 0.7 | 0.3 | nd | 4.9 | nd | nd | 14.6 |
| DARK | ||||||||||||||||||||
| Kütahya ware | MYT188 | 7.1 | 1.4 | 2.7 | 48.8 | nd | 12 | nd | 1.9 | 1.7 | nd | 4.1 | 0.4 | 2.2 | nd | nd | 2.1 | nd | nd | 15.8 |
| Kütahya ware | MYT179 | 11.6 | 1.1 | 1.5 | 60.3 | nd | 6.6 | 0.7 | 1.4 | 2.1 | nd | 0.7 | 0.4 | 0.8 | nd | nd | 0.2 | nd | nd | 12.8 |
| Kütahya ware | MYT230 | 7.2 | 1.5 | 2.2 | 52.7 | nd | 12.4 | nd | 1.3 | 3 | nd | 0.4 | nd | 1.2 | 0.3 | nd | 3.2 | nd | nd | 14.7 |
| Iznik ware | MYT170 | 9 | 0.9 | 1.04 | 47.6 | nd | 16.1 | nd | 0.8 | 0.8 | nd | 0.3 | nd | 0.8 | 0.7 | nd | nd | nd | 2.6 | 19.4 |
| Polychrome painted ware | MYT215 | 9.6 | 3.3 | 3.3 | 57.01 | nd | 5.5 | 0.6 | 1.1 | 1.04 | nd | 5.6 | 0.7 | 2.7 | 0.9 | 0.57 | nd | nd | nd | 8.2 |
| Miletus ware | MYT167 | 8.8 | 0.7 | 1.7 | 47.0 | nd | 11.6 | 0.8 | 1.3 | 0.8 | nd | 0.6 | nd | 5.8 | 1.6 | 2.8 | nd | 1.3 | nd | 15.2 |
Table 3.
Scanning electron microscopy analysis of polished samples’ glazes in the sampled pottery collection from the Castle of Mytilene in Lesvos (%); nd = non detective.
Table 3.
Scanning electron microscopy analysis of polished samples’ glazes in the sampled pottery collection from the Castle of Mytilene in Lesvos (%); nd = non detective.
| Samples | Na2O | MgO | Al2O3 | SiO2 | P2O5 | SO3 | Cl2O | K2O | CaO | TiO2 | Cr2O3 | MnO | Fe2O3 | CoO | NiO | CuO | ZnO | SnO2 | PbO | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Kütahya ware | MYT179 | average | 11.9 | 0.9 | 1.2 | 59.3 | nd | 7.2 | 0.7 | 1.2 | 1.9 | nd | nd | nd | 0.5 | nd | nd | nd | nd | nd | 15.3 |
| stdev | 0.02 | 0.04 | 0.1 | 0.2 | nd | 0.03 | 0.1 | 0.1 | 0.04 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | 0.2 | ||
| Kütahya ware | MYT184 | average | 1.4 | 0.8 | 3.2 | 38.1 | nd | 17.8 | 1.04 | 4 | 3.04 | nd | nd | nd | 1.9 | 0.3 | nd | 0.9 | nd | 3.1 | 24.5 |
| stdev | 0.1 | 0.01 | 0.2 | 0.5 | nd | 0.4 | 0.2 | 0.1 | 0.7 | nd | nd | nd | 0.1 | 0.1 | nd | 0.9 | nd | 2.1 | 0.3 | ||
| Kütahya ware | MYT188 | average | 1.1 | 0.0 | 2.3 | 64.1 | 5.4 | 10.2 | nd | 0.7 | 3.5 | nd | nd | nd | 0.6 | nd | nd | nd | nd | nd | 12.3 |
| stdev | 0.002 | 0.0 | 0.2 | 0.1 | 0.2 | 0.04 | nd | 0.1 | 0.04 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | 0.3 | ||
| Kütahya ware | MYT242 | average | 8.5 | 1.3 | 1.4 | 53.5 | nd | 9.7 | 0.9 | 0.9 | 2.9 | nd | nd | nd | 0.6 | nd | nd | nd | nd | nd | 20.4 |
| stdev | 0.03 | 0.2 | 0.4 | 0.7 | nd | 0.3 | 0.3 | 0.1 | 0.5 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | 0.5 | ||
| AVERAGE | 5.7 | 0.8 | 2.0 | 53.8 | 1.3 | 11.2 | 2.0 | 1.7 | 2.8 | nd | nd | nd | 0.9 | 0.1 | nd | nd | nd | 0.75 | 18.1 | ||
| Iznik ware | MYT168 | average | 2.1 | 0.9 | 2.2 | 42 | 10.9 | nd | 5.9 | 0.6 | 2.5 | nd | nd | nd | 1.4 | nd | nd | nd | nd | 1.3 | 30.5 |
| stdev | 1.4 | 0.5 | 1.04 | 2.1 | 0.4 | nd | 3.5 | 0.8 | 3.5 | nd | nd | nd | 0.1 | nd | nd | nd | nd | 1.8 | 7.1 | ||
| Iznik ware | MYT170 | average | 6.7 | 0.3 | 1 | 48.9 | nd | 15.9 | nd | 0.6 | 0.7 | nd | nd | nd | 0.5 | nd | nd | nd | nd | 2.4 | 23 |
| stdev | 0.2 | 0.1 | 0.8 | 1.6 | nd | 0.5 | nd | 0.1 | 0.7 | nd | nd | nd | 0.1 | nd | nd | nd | nd | 0.4 | 1.2 | ||
| Iznik ware | MYT214 | average | 9 | 0.6 | 1.1 | 50.2 | 15.1 | nd | 0.8 | 0.7 | 1 | nd | nd | nd | 0.5 | nd | nd | nd | nd | 2.1 | 19 |
| stdev | 0.4 | 0.3 | 0.1 | 0.9 | 0.03 | nd | 0.2 | 0.1 | 0.2 | nd | nd | nd | 0.1 | nd | nd | nd | nd | 0.2 | 0.3 | ||
| AVERAGE | 5.9 | 0.6 | 1.4 | 47.0 | 8.7 | 5.3 | 2.2 | 0.6 | 1.4 | nd | nd | nd | 0.8 | nd | nd | nd | nd | 1.9 | 24.2 | ||
| Glazed fritware | MYT182 | average | 6.5 | 0.7 | 0.9 | 51.3 | nd | 14.7 | 0.8 | 1.7 | 2.8 | nd | nd | nd | 0.7 | nd | nd | nd | nd | nd | 20 |
| stdev | 0.1 | 0.1 | 0.2 | 1.4 | nd | 1 | 0.3 | 0.7 | 0.2 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | 0.0 | ||
| Porcelain | MYT185 | average | 1.2 | 0.6 | 14.2 | 70.6 | nd | nd | nd | 2.8 | 9.7 | nd | nd | nd | 1 | nd | nd | nd | nd | nd | nd |
| stdev | 0.1 | 0.0 | 0.1 | 0.2 | nd | nd | nd | 0.0 | 0.1 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | nd | ||
| Porcelain | MYT186 | average | 2 | 0.5 | 14.6 | 73.8 | nd | nd | nd | 2.9 | 5.3 | nd | nd | nd | 0.9 | nd | nd | nd | nd | nd | nd |
| stdev | 0.1 | 0.1 | 0.9 | 1.5 | nd | nd | nd | 0.1 | 0.7 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | nd | ||
| Porcelain | MYT221 | average | 11.1 | 3.0 | 2.6 | 74.3 | nd | nd | 0.5 | 1.1 | 6 | 0.2 | nd | nd | 0.9 | nd | nd | nd | nd | nd | nd |
| stdev | 0.1 | 0.1 | 0.1 | 0.1 | nd | nd | 0.01 | 0.01 | 0.2 | 0.0 | nd | nd | 0.02 | nd | nd | nd | nd | nd | nd | ||
| Porcelain | MYT223 | average | 0.5 | 0.3 | 17.2 | 72.7 | nd | nd | nd | 3.5 | 5.2 | nd | nd | nd | 0.7 | nd | nd | nd | nd | nd | nd |
| stdev | 0.01 | 0.02 | 0.1 | 0.2 | nd | nd | nd | 0.01 | 0.1 | nd | nd | nd | 0.0 | nd | nd | nd | nd | nd | nd | ||
| AVERAGE | 3.7 | 1.1 | 12.2 | 72.9 | nd | nd | 0.1 | 2.6 | 6.6 | 0.1 | nd | nd | 0.9 | nd | nd | nd | nd | nd | nd | ||
| Monochrome glazed ware | MYT200 | average | 2.1 | nd | 16.7 | 27.3 | nd | 10.9 | 2.6 | 0.8 | 2.9 | 31.1 | nd | nd | 2.1 | nd | nd | nd | 2.9 | nd | nd |
| stdev | 0.6 | 0.0 | 3.3 | 2.1 | nd | 5.5 | 0.2 | 0.04 | 1 | 7.5 | nd | nd | 1.5 | nd | nd | nd | 0.8 | nd | nd | ||
| Polychrome painted ware | MYT215 | average | 11.03 | 0.6 | 1.4 | 59.4 | nd | 10.9 | 0.9 | 1.1 | 0.9 | nd | nd | nd | 0.3 | nd | nd | nd | nd | nd | 13.6 |
| stdev | 0.3 | 0.3 | 0.4 | 0.1 | nd | 0.4 | 0.02 | 0.02 | 0.1 | nd | nd | nd | 0.02 | nd | nd | nd | nd | nd | 0.3 | ||
| Miletus ware | MYT167 | average | 10.3 | 0.5 | 1.2 | 48.6 | nd | 14.8 | 1.2 | 1.1 | 0.9 | nd | nd | nd | 0.6 | nd | nd | nd | nd | nd | 21 |
| stdev | 0.1 | 0.1 | 0.1 | 0.7 | nd | 0.3 | 0.0 | 0.02 | 0.1 | nd | nd | nd | 0.0 | nd | nd | nd | nd | nd | 0.5 | ||
| Miletus ware | MYT204 | average | 7.3 | 0.7 | 1.4 | 42.5 | nd | 19.6 | nd | 0.9 | 0.6 | nd | nd | nd | 0.9 | nd | nd | nd | nd | nd | 26.2 |
| stdev | 0.1 | 0.2 | 0.3 | 0.4 | nd | 0.2 | nd | 0.1 | 0.1 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | 0.3 | ||
| AVERAGE | 8.8 | 0.6 | 1.3 | 45.6 | nd | 17.2 | 0.6 | 1.0 | 0.8 | nd | nd | nd | 0.8 | nd | nd | nd | nd | nd | 23.6 |
Table 4.
Scanning electron microscopy analysis of the polished samples’ slip coatings in the sampled pottery collection from the Castle of Mytilene in Lesvos (%); nd = non detective.
Table 4.
Scanning electron microscopy analysis of the polished samples’ slip coatings in the sampled pottery collection from the Castle of Mytilene in Lesvos (%); nd = non detective.
| Samples | Na2O | MgO | Al2O3 | SiO2 | P2O5 | SO3 | Cl2O | K2O | CaO | TiO2 | Cr2O3 | MnO | Fe2O3 | CoO | NiO | CuO | ZnO | SnO2 | PbO | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Polychrome painted ware | MYT215 | average | 3.5 | 1.3 | 3.5 | 74.5 | nd | 4.7 | 0.6 | 0.8 | 2.1 | nd | nd | nd | 0.6 | 0.4 | nd | nd | nd | nd | 8 |
| stdev | 0.1 | 0.1 | 0.3 | 0.4 | nd | 0.1 | 0.01 | 0.1 | 0.1 | nd | nd | nd | 0.1 | 0.01 | nd | nd | nd | nd | 0.3 | ||
| Monochrome glazed ware | MYT200 | average | 9.1 | nd | 1.2 | 42.4 | 0.6 | nd | nd | nd | 1.3 | 33.2 | nd | nd | 1.1 | nd | nd | nd | 11.1 | nd | nd |
| stdev | 1.3 | nd | 0.6 | 1.2 | 0.8 | nd | nd | nd | 0.1 | 4.7 | nd | nd | 0.5 | nd | nd | nd | 2 | nd | nd | ||
| Kütahya ware | MYT179 | average | 1 | 0.1 | 2.9 | 87.5 | nd | nd | nd | 3 | 5.7 | nd | nd | nd | 0.2 | nd | nd | nd | nd | nd | nd |
| stdev | 0.1 | 0.3 | 0.3 | 0.4 | nd | nd | nd | 0.2 | 0.1 | nd | nd | nd | 0.3 | nd | nd | nd | nd | nd | nd | ||
| Miletus ware | MYT167 | average | 0.8 | 1.4 | 24 | 64.2 | nd | nd | nd | 4.6 | 3.2 | 0.7 | nd | nd | 1.1 | nd | nd | nd | nd | nd | nd |
| stdev | 0.2 | 0.2 | 0.4 | 0.8 | nd | nd | nd | 0.1 | 0.2 | 0.3 | nd | nd | 0.1 | nd | nd | nd | nd | nd | nd | ||
| Miletus ware | MYT204 | average | 2 | 2.2 | 23.2 | 65.6 | nd | nd | nd | 3.1 | 2.1 | 0.8 | nd | nd | 1.1 | nd | nd | nd | nd | nd | nd |
| stdev | 0.2 | 0.1 | 1.8 | 1.7 | nd | nd | nd | 0.3 | 0.8 | 0.1 | nd | nd | 0.1 | nd | nd | nd | nd | nd | nd | ||
| Iznik ware | MYT168 | average | 1.1 | 1.1 | 2.2 | 77.3 | nd | 4.1 | 4.8 | 0.8 | 3.7 | nd | nd | nd | 0.8 | nd | nd | 0.3 | nd | nd | 4.3 |
| stdev | 0.2 | 0.1 | 0.9 | 2.3 | nd | 0.5 | 0.5 | 0.3 | 0.4 | nd | nd | nd | 0.9 | nd | nd | 0.5 | nd | nd | 3.7 | ||
| Iznik ware | MYT170 | average | 3.8 | 0.6 | 1.5 | 77.6 | nd | nd | nd | 0.6 | 0.7 | nd | nd | nd | 1.2 | 0.6 | nd | nd | nd | 0.9 | 5.6 |
| stdev | 0.0 | 0.0 | 0.0 | 0.0 | nd | nd | nd | 0.0 | 0.0 | nd | nd | nd | 0.0 | 0.0 | nd | nd | nd | 0.0 | 0.0 | ||
| Iznik ware | MYT214 | average | 2.6 | 0.5 | 2.8 | 84.8 | nd | 3 | nd | 0.6 | 3.8 | nd | nd | nd | 2.5 | nd | nd | nd | nd | nd | nd |
| stdev | 0.3 | 0.0 | 0.1 | 0.4 | nd | 0 | nd | 0.1 | 0.2 | nd | nd | nd | 0.1 | nd | nd | nd | nd | nd | nd |
Table 5.
Raman spectroscopy analysis and the main blue colorants analysed through SEM.
| Blue Colour | |||||||
|---|---|---|---|---|---|---|---|
| Pottery Typology | Samples | Minerals | Main Peaks (Raman) | Main Colorants (SEM) | |||
| Kütahya ware | MYT169 | Lazurite | 548 (vs.) | 1095 (m) | 815 (w) | ------- | |
| Kütahya ware | MYT179 | Lazurite | 547 (vs.) | 1097 (m) | 815 (w) | Cu and Fe | |
| Miletus ware | MYT204 | Lazurite | 543 (vs.) | 1080 (m) | 830 (w) | ------- | |
| Iznik ware | MYT214 | Lazurite | 547 (vs.) | 1096 (m) | 829 (w) | Cu and Fe | |
| Kütahya ware | MYT230 | Lazurite | 547 (vs.) | 1096 (m) | 815 (w) | Cu, Co, and Fe | |
| Kütahya ware | MYT242 | Lazurite | 548 (vs.) | 1097 (m) | 818 (w) | Cu, Co, and Fe | |
| Miletus ware | MYT167 | Blue Smalt | 460 (vs.) | 916 (m) | Cu, Co, and Fe | ||
| Iznik ware | MYT170 | Blue Smalt | 468 (vs.) | 918 (m) | Co and Fe | ||
| Kütahya ware | MYT184 | Blue Smalt | 462 (vs.) | 917 (m) | Cu, Co, and Fe | ||
| Polychrome glazed ware | MYT215 | Blue Smalt | 460 (vs.) | 916 (m) | Co and Fe | ||
| Porcelain | MYT221 | Blue Smalt | 460 (vs.) | 914 (m) | Co, Fe, and Mn | ||
| Polychrome glazed ware | MYT228 | Blue Smalt | 460 (vs.) | 915 (m) | ------- | ||
| Kütahya ware | MYT241 | Blue Smalt | 460 (vs.) | 915 (m) | Co and Fe | ||
| Iznik ware | MYT168 | Egyptian Blue | 435 (vs.) | 465 (s) | 1090 (m) | Co and Fe | |
| Porcelain | MYT185 | Cobalt Blue | 228 (vs.) | 536 (vs) | Co, Fe, and Mn | ||
| Monochrome glazed ware | MYT200 | Turquoise | 480 (vs.) | Cu and Fe | |||
| Glazed fritware | MYT182 | Azurite | 401 (vs.) | 765 (m) | 839 (m) | 1100 (m) | Cu, Co, and Fe |
| Kütahya ware | MYT188 | Azurite | 401 (vs.) | 765 (m) | 839 (m) | Cu, Co, and Fe | |
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MDPI and ACS Style
Panagopoulou, A.P.; Vroom, J.; Hein, A.; Kilikoglou, V. A Physicochemical Examination of Blue Shades in Pottery: Rich, Deep and Endless. Colorants 2023, 2, 453-470. https://doi.org/10.3390/colorants2020021
AMA Style
Panagopoulou AP, Vroom J, Hein A, Kilikoglou V. A Physicochemical Examination of Blue Shades in Pottery: Rich, Deep and Endless. Colorants. 2023; 2(2):453-470. https://doi.org/10.3390/colorants2020021
Chicago/Turabian StylePanagopoulou, Adamantia P., Joanita Vroom, Anno Hein, and Vassilis Kilikoglou. 2023. "A Physicochemical Examination of Blue Shades in Pottery: Rich, Deep and Endless" Colorants 2, no. 2: 453-470. https://doi.org/10.3390/colorants2020021
