Polychromatic Wall Painting Decorations in Monuments of Pharaonic Egypt: Compositions, Chronology and Painting Technique

The ancient Egyptians employed both natural and, synthetic pigments whose nature and pattern of use permit the construction of an accurate chronological scheme and the recognition, in some cases, of restriction to royal or sacred use. The present paper delineates the nature of both natural and synthetic pigments, their chronology, the identification of domestic and imported materials, and their earliest use. It also discards several polychromatic materials which were thought erroneously to be primary pigments, but which have turned out to be weathering products. A further important result of the survey of more than 1500 pigment samples is the ability accurately to date changes in bronze composition, from arsenical copper to tin bronze and finally to tin-lead bronze. This not only permits accurate dating of bronze technology to within 12 years, but also opens up the possibility of dating polychromatically decorated monuments of otherwise uncertain date.

INTRODUCTION 

Ancient polychromatic wall paintings are repositories of an enormous amount of information concerning the evolution of technologies over long periods in antiquity. In decorating their tombs, temples and other diverse sacred objects the ancient Egyptians undoubtedly sought eternal durability. Already in the Predynastic period and the early Old Kingdom natural minerals were known and used for decorations, for example gypsum and calcite for white, and ochre, hematite and goethite for brown, red and yellow respectively. Wall paintings and polychromatic decoration of cultic objects in ancient Egypt had a long tradition over three millennia. Sacred themes and cultic patterns remained substantially unchanged, but the decorations experienced continuous technological improvements and the introduction of new pigments and ingredients. The cultic rules, however, provided a distinct framework which dictated the selection of pigments and their specific use in terms of sacred royal privilege (El Goresy et al. 1986). Egyptologists have defined a systematic scheme for colour symbolisms which attempts to understand and explain cultic values and colour symbols in ancient Egypt (Kees 1943).

However, this scheme is partly based on impressions of colours, based on the present hues of polychromatic decorations. We have already convincingly demonstrated that the ancient colour hues cannot be determined from present visual impressions and perceptions because many pigments have been subjected to severe chemical reactions which have entirely changed their original colours, for example from original blue to green or from original green to brown (Schiegl et al. 1989; 1991; Schiegl 1991).

The nature of the pigment itself, whether a natural mineral or a synthetic product, conveys new information to both Egyptologists and natural scientists. The identification of pigments raises numerous questions: for example, (1) Were the natural pigments exploited from domestic sources in Egypt or were they imported, and if so, which pigments were imported at what date and from where? A systematic chronological survey of decorations in precisely dated monuments and tombs should reveal the exact date of the introduction of a new pigment, natural or synthetic, domestic or imported. This information may uncover trade relations between ancient Egypt and other states at various periods in Egyptian history. (2) Can we uncover the ancient technological procedures followed in the manufacture of synthetic pigments and precisely determine the ingredients used by the ancient Egyptians? (3) What are the implications of the knowledge gained concerning the development of technology in ancient Egypt? (4) What are the reasons for the continuous erosion of polychromatic decorations, and can we develop some means of coping with the many disintegration processes (Schiegl et al. 1991)? Answers to these questions will indeed have important consequences with regard to the evolution of technology over the millennia. Due to limited space, we will address only the first three questions in this paper. The fourth question has been adequately discussed in a PhD thesis (Schiegl 1991) and other publications (Schiegl et al. 1989; 1991).

THE PIGMENT PALETTE ACROSS ANCIENT EGYPTIAN HISTORY

In this review, I shall present a detailed survey of the inorganic painting materials used in pharaonic Egypt for wall, coffin and sarcophagus decorations from the Old Kingdom to the Roman period. The survey resulted from a comprehensive pigment investigation of more than 1500 samples collected from more than 126 well dated monuments covering a long period of ancient Egyptian history at the following sites: Bubastis, Gizeh, Saqqara, Sarabiet el Khadem (Sinai), Beni Hassan, Tuna el Gebel, Deir el Bershah, Sheikh Said, Amarna, El Hawawish, Achmim, Naga' el Deir, Qasr es Sayyad, Abydos, Temples in Thebes (Karnak, Luxor Temple, the Talatat blocks, West Thebes Ramesseum, Medinet Habu, Deir el Bahri), Valley of the Kings, Valley of the Queens, Deir el Medinah, Assasif, El Khokhah, Sheikh Abdel Qurna, Mo 'alla, El Kab, Hierakonpolis, Edfu, Kom Ombo, Aswan, Elephantine, Kalabsha, Beit el Wali, and Kanais Temple. The locations of these sites are shown in Fig. 1. This paper also includes a critical analysis of the literature published on this subject.

The nature of ancient Egyptian painting materials has been a subject of continuous study over the last 190 years. A treatise on Egyptian pigments was published by Lucas and Harris (1962) as an attempt to present a summary of the chemical composition of pigments sporadically collected from tombs, temples and artefacts. Much of the information given by Lucas and Harris is based on mere visual observations by Egyptologists or wet chemical analysis of bulk samples and hence needs basic revision. The application of accurate analytical techniques, such as X-ray diffraction, scanning electron microscopy (SEM), and electron probe microanalyses (EPMA), has revolutionised our knowledge of the nature of pigments in ancient Egyptian polychromatic decorations (Noll and Hangst 1975a; 1975b; Noll 1979; 1980; 1981; Schiegl et al. 1989; 1991; Schiegl 1991).

Until only very recently knowledge of the diversity of painting materials and their chronological evolution in ancient Egypt was quite limited (Lucas and Harris 1962). Many misidentifications of materials were made by archaeologists (numerous quotations in Lucas and Harris 1962) before the introduction of accurate instrumental analytical techniques. For example, information in the literature about the use of the natural copper minerals malachite and azurite, for green and blue respectively, turned out to be erroneous (Riederer 1974). The field was thus open to misinterpretation and speculation, for example in the misidentification of deterioration products like basic copper chloride or jarosite as genuine synthetic pigments (Riederer 1974; Noll 1979; Jaksch 1985). Unfortunately, some of these misidentifications were adopted and in some cases taken for granted without further critical analysis of the investigative procedures employed. Although systematic treatment has been attempted in many of the recent publications (Lucas and Harris 1962; Noll and Hangst 1975a; 1975b; Noll 1979; 1980; 1981), the data obtained have not been adequate to construct a meaningful chronological framework for ancient Egyptian pigments and their technological evolution over the three millennia of ancient Egyptian history.

The question of scrutinising pigment types is crucial since it links ancient scientific and technological knowledge with archaeological interests in that it gives us deeper insight into the knowledge of ore prospection and technological capabilities of the ancient Egyptians during the millennia of Egyptian history.

Painting materials used in ancient Egypt can be strictly classified into two distinct categories: (1) Natural pigments which make up a palette of natural polychromatic minerals (or their mixtures) exploited from domestic or foreign ore deposits, and (2) synthetic pigments prepared from natural raw materials and metal scrap by firing the mixtures at moderate or high temperatures.

(1) NATURAL PIGMENTS

These pigments include white, consisting of the carbonates limestone and magnesiocalcite, huntite [Mg₃Ca(CO₃)₄]and the sulphates gypsum and anhydrite; yellow, consisting of iron ochre, geothite and lepidocrocite (α and γ FeOOH), and orpiment (As₂S₃); orange, mainly realgar (As₄S₄); red, mainly hematite (Fe₂Ο₃); black, carbon or soot.

A. White pigments

White pigments belong to the earliest painting materials in use since predynastic times (Lucas and Harris 1962). This was confirmed by Noll (1980). Recent reports (Jaksch 1985; El Goresy et al. 1986; Schiegl et al. 1989; 1991) have provided chronological evidence for almost uninterrupted use from the Fifth Dynasty to the Roman period. However, here I caution against misinterpretation of the use of white paint in scenes for which the ancient Egyptians used strictly blue or green pigments. For example, Jaksch's failure (Jaksch 1985) to detect the very few grains of Egyptian Blue residue on the white background in scenes depicting water in the tombs of Ankhtifi (Mo'alla, First Intermediate period) and Setka (Aswan, First Intermediate period), led him to conclude that the artists evidently used white paint instead, in order to circumvent the problem of the lack of Egyptian Blue at that time. However, Schiegl (1991) was able to detect the few residual Egyptian Blue grains on the white paint substrate, thus indicating that the white paint was the priming coat of the original Egyptian Blue which had weathered away over time.

Prior to the New Kingdom, calcium sulphates (gypsum and anhydrite) were the dominant white pigments. Riederer (1974) discovered that huntite [Mg₃Ca(CO₃)₄], a pigment superior in its painting properties and brightness to sulphates and carbonates, was also used by the ancient Egyptians.

        Calcium sulphates (gypsum and anhydrite). Since systematic records before the Fifth Dynasty are missing, nothing is known about the exact date of the first application of gypsum and anhydrite. Both anhydrite and gypsum occur together in many Miocene formations in Egypt. Lucas and Harris (1962) reported that plaster was used in ancient Egypt for smoothing the background surface before application of the priming coat and the painted decoration. However, Jaksch (1985) claims that natural anhydrite was used. By contrast, Noll (1980) presented unequivocal evidence that anhydrite was prepared synthetically by the ancient Egyptians through mild heating of gypsum. The heated material was applied after being mixed with water, and partly recrystallised to gypsum on the decorated walls.

        Calcium carbonates. The ancient Egyptians used either pure calcite, chalk or limestone. An important technological question concerning this material is whether and when the ancient Egyptians used slaked lime. Evidence for the recognition of the advantages of slaked lime over powdered limestone due to its stronger adherence bears witness to advanced technology in decoration. Indeed, Noll (1980) reported the finding of a wall plaster from a monument of the Fourth Dynasty prepared from slaked lime. The texture of the plaster is typical of the recrystallisation which usually takes place subsequent to slaking of the decarbonated lime.

Calcium carbonates enjoyed wide application in ancient Egyptian decorations from the Fifth Dynasty until the reign of the emperor Tiberius. By contrast, magnesiocalcite has been reported sporadically, for example from the tomb of Antefoqer (Twelfth Dynasty) and from the Talatat blocks of Akhenaten's temple (Eighteenth Dynasty) in Luxor (Jaksch 1985).

        Huntite Mg₃Ca(CO₃)₄. This pigment is superior to any white painting material used in antiquity. The mineral is pure white, much brighter than calcium sulphates and carbonates. It has good suspension and adhesion properties. The pigment appeared for the first time in wall paintings during the reigns of Queen Hatshepsut and King Tuthmosis III (Eighteenth Dynasty). Although Noll (1980) reports huntite in white paint on pottery of the Eleventh Dynasty from El-Tarif, Thebes, Jaksch (1985) mentions that he found huntite in a white pigment consisting of major anhydrite and magnesiocalcite from the tomb of Antefoker (Twelfth Dynasty) in Thebes. This report, however, needs confirmation. The recognition of the superior quality of huntite compared to sulphates and carbonates by the ancient Egyptian artists is documented in the restriction of its use in pure form as a sacral privilege of pharaohs and deities in the New Kingdom, for example for the dresses of Isis and Nephtis on the sarcophagus of Tuthmosis IV (El Goresy et al., 1986; El Goresy et al. in preparation). Its application increased dramatically towards the later stages of the Eighteenth and in the Nineteenth and Twentieth Dynasties. Huntite does not occur as a natural mineral in Egypt. It is particularly notable that this superior pigment first appeared during the reign of Tuthmosis III at the same time as another imported yellow pigment (orpiment) with superior qualities. I interpret this as a strong indication that huntite is an imported material, perhaps first encountered by the ancient Egyptians during the campaigns of Tuthmosis III in the upper Euphrates.

White pigments were mainly used as a substrate for all polychromatic scenes or for hieroglyphic texts in tombs and temples. While carbonates and sulphates were the only ground pigments used for decorations in the Old and Middle Kingdoms and the First and Second Intermediate periods, lime blended with huntite was the major pigment in the New Kingdom, particularly in the Nineteenth Dynasty. In a few royal tombs, for example that of Tuthmosis IV, pure huntite was also used as a ground colour covering the priming coat (El Goresy et al. 1986; Schiegl et al. 1989; 1991).

B. Red and yellow pigments

These pigments are among the oldest recorded in ancient Egyptian history. Along with white carbonates and sulphates, they dominate wall decorations in the Old and Middle Kingdoms. In these periods pure red and yellow pigments were used. At the beginning of the New Kingdom, a variety of hues between red and yellow to pale yellow appeared in the decorations of the Eighteenth Dynasty. This development resulted not only from diluting saturated yellow and red materials with white pigments to achieve all stages of pale red and yellow, but also from blending pure red and yellow pigments with chromatically superior pigments with high reflecting properties. In the Eighteenth Dynasty a new yellow pigment, orpiment, and a new orange pigment, realgar, were introduced. The superiority of these pigments over any other yellow or red pigments was evidently recognised in the early stages of the Eighteenth Dynasty. Their use in pure form was restricted to royal tombs.

        Red ochre. The material is strictly speaking hematite (Fe₂O₃). In the Old and Middle Kingdoms, this pigment was used particularly for the depiction of male human bodies. This pattern continued in the New Kingdom and the Late period (Noll 1980; El Goresy et al. 1986; Schiegl et al. 1989; 1991; Schiegl 1991: Lucas and Harris 1962; Noll and Hangst 1975a; 1975b; Noll 1979; 1980; 1981; Riederer 1974; Jaksch 1985), though with a wide spectrum of hues including pale colours. Hematite is relatively abundant in sedimentary rocks among geological formations in the Nile valley. It occurs there as lenses or pockets which are easy to exploit.

        Yellow ochre. This pigment consists of the oxyhydrides of iron goethite (γ FeOOH) and lepidocrocite (α FeOOH). Like hematite, it occurs in the Nile valley in pockets in sandstones, shales and in gossans of iron and copper sulphide deposits. Its use has been traced back to the Fifth Dynasty, and it continues into the Roman period (El Goresy et al. 1986). Another possible domestic source of yellow ochre is the iron deposit in the Bahariya oasis in the Western desert. In the Eighteenth Dynasty, specifically during the reign of Queen Hatshepsut (at her sanctuary in Karnak: Jaksch 1985; El Goresy et al. 1986), yellow ochre was blended with orpiment to enhance its brightness and reflecting properties.

        Orpiment AS₂S₃. This pigment is superior to all other polychromatic pigments. It has a dense golden yellow colour with high brightness and an outstanding gold gleaming shiny glaze. The ancient Egyptians recognised its special quality in comparison to other yellow pigments. Orpiment was first mentioned by Lucas and Harris (1962) who reported that it first appeared in the second half of the Eighteenth Dynasty. Terrace and Braziller (1968) reported orpiment from decorations on the coffin of Djhuti-nakht (Eleventh Dynasty) in the necropolis of Deir el Bershah. Saleh and Eskander (Saleh et al. 1974) identified orpiment in a bundle filled with shiny yellow micaceous flakes found in the tomb of Kheruef in Thebes (reign of Amenophis III) by the University of Chicago. Another sample was also collected in 1922 by Howard Carter from the tomb of Tutankhamun; it was identified as a mixture of orpiment and realgar (As₄S₄)and kept in the Egyptian Museum in Cairo. In the New Kingdom (and particularly during the Eighteenth Dynasty) the pure pigment was an object of sacred royal privilege, since its use was strictly confined to the royal sarcophagi in the tombs of the pharaohs of the Eighteenth Dynasty from Tuthmosis III (contra Lucas and Harris 1962) to Horemheb (Jaksch 1985; El Goresy et al. 1986) and a few other pharaohs of the Nineteenth and Twentieth Dynasties (see Chronological section below, pp. 67-69). Its liberal use was also encountered in wall decorations in the tomb of Tuthmosis IV (El Goresy et al. 1986). Orpiment does not occur in any ore deposit in Egypt, and it is thus an imported substance. In contrast to Terrace and Braziller (1968), Jaksch (1985) and El Goresy et al. (1986) have recorded the first appearance of orpiment in ancient Egyptian decorations as not earlier than the reign of Queen Hatshepsut (Eighteenth Dynasty). The controversy over whether it first appeared during the Eleventh Dynasty or several hundred years later in the Eighteenth Dynasty is of some importance for precisely dating the first import of orpiment and thus of trade relations with its area of origin.

A systematic survey of the sarcophagi of New Kingdom pharaohs of the Eighteenth to Twenty-first Dynasties (Jaksch 1985; El Goresy et al. 1986; El Goresy et al. in preparation) has revealed an interesting

pattern in the decoration of these royal sarcophagi. Orpiment appears for the first time in the

decoration of the red sandstone sarcophagus of Tuthmosis III in his tomb in Thebes. The pigment is applied generously in the painting of the hieroglyphs and of the deities. The paint is covered by a thin layer of mastics which have now turned deep brown in colour through the aging of the resin. It is subsequently encountered in the decorations of the sarcophagi of the pharaohs Amenophis II and Tuthmosis IV, the broken remains of the sarcophagus of Amenophis III, and the sarcophagi of Tutankhamun and Horemheb. Surprisingly, pure orpiment was also encountered in all the wall decorations in the tomb of Tuthmosis IV (El Goresy et al. in preparation). My survey of royal tombs in the New Kingdom indicates that the tomb of Tuthmosis IV is an exception. The red sandstone sarcophagus of Tuthmosis II and the two red sandstone sarcophagi of Queen Hatshepsut (as Queen consort to Tuthmosis II and as Ka-Ma_cat-Ra respectively) in the Egyptian Museum in Cairo are devoid of any painted decorations. Also bare of any decoration is the granite sarcophagus of Akhenaten in the Egyptian Museum in Cairo. The richest orpiment decorations were encountered (in decreasing quantities) on the sarcophagi of Tuthmosis IV, Tuthmosis III, Horemheb, Amenophis II and Amenophis III. By contrast, the sarcophagus of Tutankhamun displays only a very thin layer of orpiment on both deities and hieroglyphs. In the royal tombs of the Nineteenth Dynasty the pigment was found only in the decorarion of the red granite sarcophagus of Ramses I, while the sarcophagi of his successors display Egyptian Blue as the major decorating pigment, but no orpiment. Table 1 depicts in detail the pattern of orpiment use for royal sarcophagi in the Eighteenth Dynasty and early Nineteenth Dynasty.

The decorations of the royal sarcophagi of the pharaohs of the Eighteenth Dynasty bear witness to the sophisticated technical knowledge of ancient Egyptian artists during that period. Detailed microscopic investigations indicate that the artists were fully aware of the high degree of reflection and the gleaming properties of the cloven orpiment flakes. The ore is only coarsely ground, and painted or pasted unsieved in such a manner that the orpiment flakes of various sizes would display a gold shining glaze regardless of the angle of observation. It is conjectured that this kind of orpiment decoration was intended to simulate gold plated decoration which was a sacred privilege of the god pharaoh. The continnous use of this pigment for more than 140 years indicates uninterrupted import from the reign of Tuthmosis III. During this period decorations using pure orpiment are never encountered in tombs other than those of the pharaohs. By comparison, however, in the later New Kingdom and the Late period the pigment was also used for decorating limited surface areas of coffins. Indeed, it is quite bafffing that a superior pigment like orpiment, which was the subject of royal sacred privilege during the Eighteenth Dynasty should have been abandoned by the pharaohs of the Nineteenth and subsequent Dynasties and have become a material used for decorating the coffins of commoners. The reason for this change in the status of the pigment over time remains obscure.

        Yellow ochre blended with orpiment. By contrast with the use of pure orpiment in wall paintings of the royal tomb of Tuthmosis IV, yellow ochre blended with orpiment is omnipresent in wall decorations of the New Kingdom from the time of Queen Hatshepsut down to the Twentieth Dynasty and the Late and Roman periods. Orpiment was evidently not simply mixed with yellow ochre, but was applied in a distinct painting sequence: an ochre layer on the carbonate priming coat, followed by a very thin orpiment layer (a few tens of microns in thickness), followed by a final thin yellow ochre layer. This painting technique has been discovered in the wall paintings in the baptism scene of Queen Hatshepsut in her room in Karnak and in many decorations in the temple of Deir el Bahri (Jaksch 1985; El Goresy et al. 1986).

C. Orange

        Realgar (AS₄S₄). Like orpiment, realgar has high reflecting and gleaming properties with a saturated orange to deep red glittering glaze. So far, it has been found only in the wall decorations of the royal tomb of Tuthmosis IV and never reappears in later periods of ancient Egypt (El Goresy et al. in preparation). Realgar is also an imported material. The mineral usually occurs together with orpiment in nature. A common source for both orpiment and realgar cannot be excluded.

D. Black

        Soot. Black painted decorations have frequently been reported from monuments of the Old Kingdom (many citations in Lucas and Harris 1962). In the last 100 years, numerous Egyptologists and natural scientists have reported the presence of black painted decoration on monuments from the Old Kingdom

to the Roman period (Lucas and Harris 1962; El Goresy et al. in preparation). All kinds of carbon black marerials were believed to have been identified, for example soot, carbon black ('lamp black'), charcoal, bone black and pyrolusite (Lucas and Harris 1962). I would like to stress the fact that the majority of these reports have resulted solely from visual assessments made by archaeologists before the introduction of reliable scientific methods of material research. As a result, it should be emphasised that the various claims of charcoal, lamp black or soot having been used in the monuments in question are not reliable, and require careful scrutiny by scientific methods. The firm identification of any of these materials depends on investigation with high resolution electron microscopic techniques. Soot was probably prepared from burning wood or animal bones (Lucas and Harris 1962; El Goresy et al. in preparation). In the New Kingdom soot was mixed with lime to produce a grey pigment with a faint blue tinge (for example, the tomb of Ramose No. 55 in Thebes). Noll (1975a; 1975b; 1979; 1980) has verified the presence of pyrolusite in wall paintings in monuments of the Middle and New Kingdoms.

2) SYNTHETIC PIGMENTS

Evidence for synthetic pigments dates from as early as the Fourth Dynasty (Noll 1980). As far as the manufacture of synthetic pigments was concerned, the ancient Egyptians confined their technological interest to blue and green. Blue and green pigments in ancient Egypt enjoyed a remarkable technological development which demonstrates the persistence of the ancient Egyptians in their attempts to meet the demands of sacral requirements. A systematic survey of more than 1500 pigment samples collected from more than 126 monuments in Egypt has revealed that at no time did the ancient Egyptian artists apply any natural green and blue minerals like malachite, chrysocolla, atacamite, paratacamite or azurite for wall decorations (Schiegl et al. 1989; 1990; 1991). These findings refute all previous claims for the use of natural green and blue copper minerals for the decoration of Egyptian monuments throughout the three millennia of ancient Egyptian history (Lucas and Harris 1962; Riederer 1974). All malachite, atacamite or paratacamite encountered in wall decorations has turned out to be of secondary origin, due to the deterioration of synthetic blue and green copper pigments (Schiegl et al. 1989; 1991). Chrysocolla reported from the blocks of the pharaoh Mentuhotep (Riederer 1974) has not been confirmed by Jaksch (1985) who found only Egyptian Blue in the decorations of the same blocks (Riederer 1974; Jaksch 1985). Over the millennia, five different synthetic pigments with a distinct chronological pattern were manufactured in ancient Egypt: (1) blue copper-bearing alkali rich glass in the Old Kingdom and until the beginning of the New Kingdom; (2) probably bottle green (or brown, depending on the oxidation state of the iron) iron-potassium bearing glass in the Old Kingdom down to the Second Intermediate period; (3) Egyptian Blue from the Old Kingdom to the Roman period; (4) green copper-bearing wollastonite from the Eighteenth Dynasty until Roman times; and (5) Amarna Blue, a cobalt aluminate spinel which was used only in the decoration of pottery during the reigns of Amenophis III and Akhenaten, and died out in the early Nineteenth Dynasty. The chronological conspectus indicates that the ancient Egyptian artist very probably had no green pigment, either natural or synthetic, on his palette before the New Kingdom.

A. Blue copper-bearing glass pigment

This pigment is heavily weathered in all samples collected from the various sites. Its identity as a copper glass pigment can be confirmed through analysis of the extant intact glass. The glass is in general a copper silicate glass with lesser contents of sodium, magnesium and chlorine, and minor contents of calcium and iron. Its copper content varies between 19 wt. % and 59 wt. %. The technological knowledge involved in the manufacture of this pigment probably emerged from the experience gained in the production of blue Egyptian faience which already existed in the Early Dynastic period. The presence of sodium and chlorine in this glass provides evidence of the use of a salt flux during fusion of the ingredients, in order to lower the melting point. The chemical composition of this glass is broadly related to, but distinguishable from, that of the blue Egyptian faience. Blue Egyptian faience also contains sodium and chlorine indicating the use of a flux. The pigment (and its secondary weathering products malachite, atacamite or paratacamite) has been positively identified in tombs of the Old Kingdom in Gizeh (Idu, No. G 7102, Sixth Dynasty), Saqqara (Nefer, Ptahhotepe, Fifth Dynasty; Princess Idut, Sixth Dynasty), El Hawawish (Gehesa, Sixth Dynasty), and the Middle Kingdom in Thebes Deir el Bahri (Kheti, No. 311, Eleventh Dynasty), Beni Hassan (Kheti, No. 17, Eleventh Dynasty), Deir el Bershah (Djehutihotepe, No.2, Twelfth Dynasty). The majority of the tombs studied in El Hawawish, Beni Hassan, Deir el Bershah and Sheikh Said were found to contain solely the secondary products malachite and atacamite(or paratacamite), or one of these with pseudomorphs of the original glass grains. It is thus concluded that the original pigment was the blue copper-bearing glass pigment. One has therefore to keep in mind that the original pigment applied by the ancient Egyptian artists was blue and not green. The socondary green products resulted from the alteration of the glass by weathering. These findings have to be taken into account in evaluating colour symbolism in ancient Egypt.

B. Brown (or red) and bottle green glass pigment

This pigment is also heavily weathered, producing secondary, well crystallised clusters of idiomorphic jarosite KFe₃[(OH)₆/(SO₄)₂]. The original glass pigment was a potassium-and iron-rich silicate glass. Until recently, this pigment remained unrecognised because of its pervasive alteration to jarosite, and because the overwhelming majority of scholars used for their investigations either X-ray diffraction techniques and/or SEM analysis of unpolished pigment surfaces. Since glass is amorphous, X-ray diffraction is incapable of revealing it. The SEM surface investigations failed to uncover it because of its scarcity and its enclosure within large jarosite crystal clusters. Chemical analysis of the residual glass has revealed that it contains silicon, iron, potassium, aluminium and chlorine as major elements, and magnesium and titanium as minor elements. The pigment seems to have been used widely for decorations in the Old Kingdom, for example in the pedestal of the statue of Himwnw (Fourth Dynasty, Gizeh; now in the Roemer and Pelizaeus Museum in Hildesheim), the Middle Kingdom, for example the tombs of Deir El Bershah such as those of Ahanakht (Eleventh Dynasty), Djhutihotpe (Twelfth Dynasty), and on several wooden models and statues belonging to the Middle Kingdom and the Eighteenth Dynasty (Schiegl 1991). Its abundant application can be envisaged from the omnipresence of the characteristic texture of typical idiomorphic crystal clusters of secondary jarosite, even though the relicts of the original glass are missing. I estimate that the original colour of this glass pigment was brown. This may be concluded from the fact that the jarosite on the pedestal of the statue of Himwnw occurs in the figure of a lion which could not originally have been painted green. However, the application of green glass prepared under reducing conditions cannot be excluded in other tombs. A sodium variety of jarosite, very probably originally a sodium-rich glass, was reported by Jaksch (1985) from the tombs of Akhethotpe (Fifth Dynasty) and Mereruka (Sixth Dynasty) in Saqqara.

C. Egyptian Blue

The composition of Egyptian Blue and the recipe for its preparation have been established through experimental analytical techniques and experimental investigations (Schiegl et al. 1989; 1991; Noll and Hangst 1975a; 1975b; 1979; 1980; 1981; Bayer and Wiedemann 1976). The pigment is a multicomponent mixture of cuprorivaite (CuCaSi₄O₁₀), cuproan wollastonite (CaCu)SiO₃, silica polymorphs (tridymite, cristobalite or quartz), and an alkali-and chlorine-bearing cuproan glass phase. For the manufacture of Egyptian Blue three initial components are required: (1) a copper-bearing ingredient (e.g. malachite), (2) lime, and (3) silica. All these initial materials were accessible to the ancient Egyptians: malachite in the oxidation zones of copper sulphide deposits in the Eastern desert, and lime and quartz sand in sedimentary rocks along the Nile valley. The occurrence of an alkali-rich copper-and chlorine-bearing glass between the cuprorivaite crystals provides evidence of the use of an alkali-bearing flux during the melting process to lower the melting temperature.

Egyptian Blue may be prepared from the above mentioned ingredients according to the following reaction (Bayer and Wiedemann 1976):

Cu₂[(OH)₂/CO₃] + 8SiO₂ + 2CaCO₃=>2CuCaSi₄O₁₀ + 3CO₂ + H₂O

This recipe has been widely accepted as the most probable procedure adopted by the ancient Egyptians. However, in the seventh book of his De architectura (33-22 BC), dedicated to the emperor Augustus, Marcus Vitruvius Pollio records having observed the manufacture of Egyptian Blue in Alexandria from copper-bearing metal filings, sand and salt flux. The original Latin text reads as follows:

Caeruli temperationes Alexandriae primum sunt inventae, postea item Vestorius Puteolis instituit faciundum. Ratio autem eius, e quibus est inventa, satis habet admirationis. Harena enim cum nitri flore conteritur adeo subtiliter, ut efficiatur quemadmodum farina; et aes cyprum limis crassis uti scobis facta mixta conspargitur, ut conglomeretur; deinde pilae manibus versando efficiuntur et ita conligantur, ut inarescant; aridae componuntur in urceo fictili, urcei in fornace: ita aes et ea harena ab ignis vehementia confervescendo cum coaruerint, inter se dando et accipiendo sudores a proprietatibus discedunt suisque rebus per ignis vehementiam confectis caeruleo rediguntur colore. (De architectura vii.11.1).

[The artificial preparation of Caerulium (Egyptian Blue) was first invented in Alexandria. Later Vestorius also erected a factory in Puteoli. The method of manufacture deserves great admiration. Sand and natron have to be rubbed together so finely that the mixture turns to powder; and copper grated with coarse file tools so that when the scrapings are mixed together and sprinkled with water they adhere together. Then the mixture is rolled into balls by hand and these are put together to dry. After drying, they are put in an earthen pot and (the pots) are placed in a scorching oven. When the copper and sand are thoroughly heated in a fierce fire and have melted together, they release their properties through the mutual exchange of vapours, and, once this is effected, they are found to have taken on a blue colour.]

Vitruvius did not mention an important ingredient, namely limestone without which no Caerulium could be synthesised. It is not clear if he forgot to mention limestone or if the manufacturers in Alexandria deliberately excluded it to keep the secret and maintain their manufacturing superiority and monopoly.

If Vitruvius's report reflects a genuine eye witness account of the manufacture of Egyptian Blue in factories in Alexandria shortly after Augustus conquered Egypt, then the following implications emerge: (1) During the Ptolemaic period copper-bearing metal scrap was definitely used for the manufacture of Egyptian Blue. The question thus arises as to whether this procedure was also followed by ancient Egyptians in earlier periods. If this is the case, then (2) the compositions of the metal scrap should be fingerprinted in Egyptian Blue manufactured in different periods of ancient Egyptian history. A systematic analysis of Egyptian Blue collected from precisely dated monuments should reveal whether the composition of the metal scrap used at the time was arsenical copper, tin bronze or tin-lead bronze. Residues of arsenic, tin or lead ought to be encountered in the pigments prepared from contemporary copper-bearing metal scrap. Saleh et al. (1974) reported the presence of 1.76% tin in an Egyptian Blue sample collected from the tomb of Kheruef (reign of Amenophis III Eighteenth Dynasty). Unaware of Vitruvius's report, these authors attributed the presence of tin to contamination from the copper ore from which the pigment was manufactured. This possibility can easily be dismissed since there is no copper sulphide ore in Egypt with such high concentrations of tin. On the other hand, the tin-bearing ores in Egypt are poor in copper, so that they could not have been used by the ancient Egyptians for the manufacture of Egyptian Blue. Another strong argument against the use of tin ores is the fact that these ores also contain appreciable amounts of wolframite and molybdenite, and, consequently, tungsten and molybdenum would have been found in tin-bearing Egyptian Blue pigments. Jaksch et al. (1983) reported the presence of cassiterite and a poorly characterised calcium-and tin-silicate in Egyptian Blue samples from the reign of Tuthmosis III in the New Kingdom to Roman times. They attributed the presence of the tin-bearing phases to a technological innovation involving the use of bronze for the manufacture of Egyptian Blue. A systematic study of samples collected in monuments from the Old Kingdom (Fifth Dynasty) to the reign of the emperor Tiberius (Schiegl 1991) has revealed that, on the contrary, the presence of the tin-bearing compounds in Egyptian Blue is by no means due to the sort of technological innovation in the New Kingdom envisaged by Jaksch et al.. Schiegl et al. (1991) and Schiegl (1991) have been able, on the other hand, unequivocally to identify the unknown calcium-till-silicate as malayaite (CaSnSiO₅).

The dating of ancient Egyptian copper-bearing alloys and bronze artefacts has always been problematic, and the results obtained are either inconclusive or inconsistent as a result of the following difficulties: (1) Only a few artefacts are inscribed and can be dated by this means. (2) Shapes of artefacts did not change much over the three millennia, and imitations of earlier forms were quite common during later periods. (3) Estimations of date which rely purely on art historical considerations are not reliable. The comprehensive chemical survey undertaken by Cowell (1987) clearly demonstrates the severe limitations of the art historical dating of uninscribed metal artefacts. Cowell (1987) concludes from the analyses of artefacts dated on art historical grounds that tin bronze was already manufactured in the Early Dynastic period. A statistical analysis of 270 metal objects studied by him reveals that 6% of the tin bronze artefacts have been dated by Egyptologists to the Early Dynastic period and the Old Kingdom, 13% to the First Intermediate period and the Middle Kingdom, and 40% to the Second Intermediate period. This leads to the conclusion that 59% of the bronze artefacts must belong to periods predating the New Kingdom.

If the dating of the uninscribed artefacts studied by Cowell were to turn out to be correct, then two difficulties emerge: (1) Two copper-bearing alloy technologies (arsenical copper and tin bronze) must have coexisted simultaneously for 1500 years from the Early Dynastic period until the reign of Tuthmosis III in the New Kingdom (1479-1425 BC). (2) All recycling of the different alloys from the Early Dynastic period until the reign of Tuthmosis III must have been carried out painstakingly in separate recycling workshops without any mixing of the different alloys, either together or with a third ingredient. This seems very unlikely, if not impossible, since no evidence for chemical dichotomy has been encountered in the pigments collected from monuments erected before the New Kingdom.

Cuprorivaite (CuCaSi₄O₁₀) is the dominant phase in Egyptian Blue. Contrary to the view of Saleh et al. (1974), the phase is stoichiometric and does not contain any alkalis. Along with cuprorivaite, subordinate cuproan wollastonite, an alkali-rich chlorine-bearing glass phase, and silica minerals are also present. The systematic survey has revealed the presence of arsenic-bearing phases and tin-rich minerals in a distinctive chronological pattern. Almost every pigment studied from monuments erected in the time between the Fifth Dynasty and the early Eighteenth Dynasty (Queen Hatshepsut) contains small lath-like crystals (up to 5 μm) of an arsenic-rich phase. Quantitative electron microprobe analyses have revealed that the compound is a complex calcium arsenate-phosphate (Schiegl et al. 1991; Schiegl 1991). The As₂O₃ content varies between 16.18 and 72.6 wt. %. From the analyses which have been carried out (Schiegl 1991), it is evident that the As₂O₃ and P₂O₅ contents are anticorrelated, thus indicating that the phase is indeed an arsenate-phosphate solid solution.

Pigments collected from monuments erected from the post-Hatshepsut period of the New Kingdom down to the Late period and the Ptolemaic and Roman periods contain both cassiterite (SnO₂) and the calcium-tin-silicate. According to Jaksch et al. (1983), these compounds appear for the first time in pigments collected from monuments and tombs erected during the reign of Tuthmosis III. Quantitative electron microprobe analysis of the calcium-tin-silicate has revealed that the phase is malayaite (CaSnSiO₅) (Schiegl 1991). Cassiterite occurs abundantly in the glass as idiomorphic tetragonal crystals associated with malayaite. In many cases it is also found without malayaite.

The results indicate that there is indeed a distinct chronological distribution of arsenic and tin which may perhaps indicate that the recycling of arsenical copper and bronze scrap for the production of Egyptian Blue reflects the relative chronology of arsenical copper and tin bronze at the time of manufacture of the pigment. This conclusion could be subjected to a critical test which would confirm or refute it. Since bronze artefacts in Ptolemaic and Roman times contain appreciable amounts of lead (Pernicka 1986), Egyptian Blue manufactured in these periods should also contain lead in addition to the tin minerals. A detailed search for lead-bearing compounds in samples collected from the period between the Eighteenth Dynasty and the reign of the emperor Tiberius has revealed the presence of lead in the glass phase in pigment samples collected from monuments erected between the end of the Nineteenth Dynasty and 81 AD and later in the Roman period (Schiegl et al. 1990; Schiegl 1991). The glass phase in a sample of Egyptian Blue collected from columns in the Kom Ombo Temple which were erected during the reign of the emperor Tiberius (AD 14-37) contains appreciable amounts of lead (Schiegl et al. 1990; Schiegl 1991). Lead first appears in the glass phase in tombs furnished at the end of the Nineteenth Dynasty. Another example of lead-bearing glass was found in a Green Frit pigment layer in the tomb of Basa (Twenty-sixth Dynasty). The lead contents vary between a fraction of a percent and 23.5 wt. % (Schiegl et al. 1989).

Table 2 provides a chronological list of all monuments studied from the Old Kingdom down to the Roman period. The distribution of arsenic, tin and lead indicates unequivocally that the pattern reflects the compositions of the copper-bearing ingredients. I am almost certain that the patterns reflect the compositions of the copper alloys currently in use at these times, which were recycled in scrap form for the manufacture of blue and green pigments. Since the pigment samples were collected from accurately dated monuments, the distribution patterns of arsenic, tin and lead allow a precise chronological scheme which reflects the copper alloys and bronze technology used in Egypt over a period of three millennia. Our findings indicate that arsenical copper was in use from the Old Kingdom until the end of the reign of Queen Hatshepsut (1479 BC). The introduction of bronze technology first took place during the reign of Tuthmosis III (1479-1425 BC). The manufacture of lead bronze was introduced at the end of the Nineteenth Dynasty, that is, not before the reign of Sethos II (1203-1196 BC), but not later than that of Tauseret (1190-1184 BC) (Schiegl et al. 1990; Schiegl 1991). The element of chronological uncertainty in this scheme is certainly less than 12 years. It represents the most precise chronological record of metallurgical technology in the whole of antiquity.

D. Green Frit, wollastonite

This pigment was first identified by Noll and Hangst (1975) and Noll (1979; 1980; 1981) in the paintings of the tombs of Tjanuni, No. 74 and Horemheb, No. 78 (both of the Eighteenth Dynasty). It is of dear chronological significance since the ancient Egyptians of the Old and Middle Kingdoms did not master the manufacture of a green pigment with an established specific chromatic hue. Its manufacture bears witness to a technological breakthrough in the precise estimation of ratios in the mixture of the same initial ingredients used in the manufacture of Egyptian Blue, in order to produce another pigment with a different colour. In the manufacture of Green Frit, a higher lime-to-copper ratio than for Egyptian Blue is required in order to stabilise the copper-bearing wollastonite as a liquidus phase. By comparison with Egyptian Blue, the chromatic phase in the Green Frit is wollastonite [(CaCu)SiO₃]. Like Egyptian Blue, Green Frit is a multicomponent pigment consisting of major green wollastonite, a blue copper-, sodium-and chlorine-bearing glass phase, sporadic cuprorivaite, silica minerals and the tin compounds cassiterite and malayaite (Schiegl et al. 1989). The presence of sodium and chlorine in the pigment indicates the addition of a salt flux to lower the melting temperature. A detailed survey of Green Frit samples from numerous tombs indicates that the wollastonite-to-copper glass ratios vary considerably in the materials studied (Schiegl et al. 1989). Since the overall chromatic hue is directly related to the green wollastonite/blue glass ratio, the colour perception (green, or bluish green) qualitatively reflects this ratio. The tin compounds encountered again indicate that tin bronze scrap was used as a copper ingredient (Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation). The glass phase in samples collected from monuments erected in the late Nineteenth Dynasty to the Roman period contained lead (Schiegl et al. 1989; 1990). As a result of his experimental study, Ulrich (1979) postulates that Green Frit was produced in ancient Egypt by heating the same starting mixture as for Egyptian Blue under reducing conditions. Above 1050°C. cuprorivaite would then break down to cuprite + wollastonite + silica according to the following reaction:

 2CaCuSi₄O₁₀ => Cu₂O + 2CaSiO₃ + 6SiO₂ + 1/2 O₂

Cuprorivaite         Cuprite Wollastonite Silica

The reduction would not only lead to the formation of two wollastonite molecules, but also to six silica molecules and one cuprite molecule. One would then expect to have a silica-rich pigment with more than 9% of the reddish brown cuprite, which would chromatically degrade the quality of the pigment to dirty reddish (or brownish) green. In no Green Frit samples studied were any such high concentrations of silica found (Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation). In addition, cuprite is either missing or present only in diminishing amounts (Jaksch 1985; Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation).

The pigment was first recorded in wall paintings of the following tombs of the Eighteenth Dynasty at the beginning of the New Kingdom: Ahmose (No.5), Paheri (No.3), Renni (No.7) in El Kab, and Satem in Edfu (Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation). From then on, it is encountered in the majority of tombs from the Eighteenth Dynasty until the reign of the emperor Tiberius (Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation). A detailed scrutiny of green pigments in monuments erected before the Eighteenth Dynasty has revealed that the green chromatic material is either secondary basic copper chloride (paratacamite) or secondary malachite, formed by weathering of blue glass pigment or the glass phase of Egyptian Blue (Schiegl et al. 1990; Schiegl 1991). These findings refute all previous reports of Green Frit before the Eighteenth Dynasty, and establish this pigment as a new technological achievement of the early Eighteenth Dynasty.

E. Amarna Blue, cobalt aluminate spinel

This pigment was first discovered by Riederer (1974) in pottery decoration of the Eighteenth Dynasty, and was subsequently thoroughly investigated by Noll and Hangst (1975) and Noll (1978; 1979). The pigment itself is intriguing for several reasons: (1) Cobalt aluminate spinel does not occur as a natural mineral, and must therefore be a synthetic product. (2) Cobalt does not occur in exploitable amounts in any ore deposit in Egypt. Consequently, either the raw cobalt ingredients or the manufactured pigment itself are imported. The composition of the pigment is distinct from the blue cobalt glass that appeared in the Eighteenth Dynasty (Lucas and Harris 1962). Noll and Hangst (1975) established the identity of the colourant compound as belonging to the crystal structure of spinel, and the composition as a cobalt-rich member of the aluminate spinel series. Their energy dispersive analysis revealed major cobalt, iron, nickel, zinc, manganese, calcium, aluminium, potassium, chlorine and sulphur. They were able to attribute the presence of calcium and sulphur to gypsum and calcium sulphate semihydrate painting paste. The cobalt/aluminium ratio they deduced from the bulk analysis was insufficient to satisfy the 1/2 ratio of stoichiometric spinels. Unaware of the fact that both cobalt and aluminium partition differently between spinel and potassium-rich glass, they erroneously concluded that the compound is a cobalt deficient spinel, a compound known for its high stability in comparison to the stoichiometric cobalt aluminate spinel. The presence of gypsum and calcium sulphate semihydrate presented convincing evidence that the pigment was applied as a cold paint on the fired pottery. However, this conclusion was challenged by Riederer (1974) who, on the basis of surface observations, claimed that the pigment was prepared by the process of firing its ingredients together with the pottery. My high resolution SEM investigations (El Goresy et al. in preparation) of coherent strips of pigment, carefully cut together with the pottery substrate from pottery fragments collected from Amarna, have shed more light not only on the nature of the pigment but also on the manufacturing procedure. The pigment consists of large fragments of aluminium-and potassium-rich silicate glass aligned parallel to the surface of the pottery. The cobalt spinel is present as fine-grained  (< 3 microns) idiomorphic octahedral crystals arranged in swarms of clusters in the potassium-rich glass. The interstices between the spinel-bearing glass fragments are filled with idiomorphic crystals of gypsum and anhydrite. This indicates unequivocally that both the pigment fragments and the plaster painting vehicle were applied together cold on the pottery, with the result that the sulphates crystallised during the cold drying process. Futhermore, the interfaces between the iron rich pottery and the spinel-bearing glass fragments are quite sharp, with no sign of any chemical reaction between the glass and the pottery. I see, for example, no evidence of cobalt diffusion from the potassium-rich glass to the iron oxides in the pottery, or iron diffusion profiles from the oxides in the pottery to the cobalt spinel. If the pigment decoration had taken place in what Riederer calls 'hot decoration' during the process of firing raw pottery decorated with the ingredients of the pigment, one would expect to find cobalt in magnetites in the surface of the pottery, and, conversely, iron-rich cobalt spinels in the fragments in contact with the pottery substrate. My results clearly refute Riederer's claim (1974), and unequivocally support the conclusions of Noll and Hangst (1975a; 1975b). Cobalt is not, however, the main element of the spinel as Noll and Hangst (1975a; 1975b) believed. The crystals contain almost equal quantities of iron, cobalt and nickel. Zinc is located as a minor element in the spinel, not in the glass. The chemical composition of the spinel does not deviate from stoichiometry. The glass, however, contains appreciable concentrations of aluminium and cobalt. The material balance of the bulk pigment thus does not reflect the composition of the spinel. Noll and Hangst (1975a; 1975b) state that zinc acts as a stabiliser in the cobalt pigment. However, the combination of cobalt, nickel, iron and zinc is particularly baffling because zinc does not occur along with cobalt and nickel in any natural ore deposit. The association of cobalt, nickel and iron minerals in the same ore is well known from many sulphide deposits, while the zinc-sulphide sphalerite (ZnS) is usually associated with either copper-iron sulphides (e.g. chalcopyrite, pyrrhotite and pyrite) or with galena (PbS) in lead-zinc ores. The association of zinc with cobalt, nickel and iron in the spinel may indeed represent deliberate mixing, as argued by Noll and Hangst (1975a; 1975b), in order to produce a durable pigment which is resistant to weathering. The pigment first appeared during the reign of Amenophis III (Eighteenth Dynasty), and disappeared in the reign of Ramses II (Nineteenth Dynasty). Contrary to earlier reports (frequently cited in Lucas and Harris 1962), our survey (El Goresy et al. in preparation) indicates that it was used exclusively for the decoration of pottery, and never in the decoration of walls, coffins or sarcophagi.

(3) DISCARDED 'PIGMENTS'

The unequivocal recognition of an ancient Egyptian primary pigment from secondary deterioration products requires special sampling procedures and a combination of several analytical techniques. It is essential to avoid scratching loose powder samples from the wall or the decorated object, since this procedure will certainly destroy the original texture of the coherent pigment layer and its relationship to the priming coat, the ground paint and the stucco. Very small strips (1 to 2 mm) from the pigment layer down to the substrate should be removed as coherent pieces. The application solely of X-ray diffraction to the powder will also lead to the loss of important information and inevitably to erroneous conclusions: (1) The study of the powder with X-ray diffraction alone will only disclose the identities of the crystalline minerals in the samples, while their precise chemical compositions will remain undiscovered. No information can be gained as to which compound detected by X-ray diffraction is the primary compound and which one is formed by weathering. (2) Amorphous material like glass will not be detected by means of this technique. (3) The texture of the original pigment, its relationship to the priming coat (or stucco), and the composition, texture and location of weathering products will remain entirely unrevealed. One solution to this problem is to study the collected strips with the SEM after polishing the surface of the cut from the pigment layer down to the substrate. The section will display all layers in their undisturbed original sequence as painted by the ancient Egyptian artists, and will disclose the chemical reactions which have resulted in secondary products over the millennia.

The application of X-ray diffraction on its own, without any attempt to uncover the textural relationships, has led to erroneous claims of 'newly discovered pigments'. In this section, I would like to discard six compounds believed to be genuine pigments (Lucas and Harris 1962; Riederer 1974; Noll 1979; 1980; 1981; Terrace and Braziller 1968) and recently proven to be secondary deterioration products (Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation). These should consequently be removed from the list of ancient Egyptian painting materials.

Green: atacamite (and paratacamite), malachite, copper phosphates

All these materials were formed as a result of devitrification and subsequent weathering of the blue glass pigment or the blue glass phase in Egyptian Blue (Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation). The first two were recorded in monuments from all sites and periods (Schiegl et al. 1989; El Goresy et al. in preparation). The phosphates in particular are the result of bats living in the tombs for thousands of years, for example in numerous tombs at El Hawawish, Mo 'alla, Deir el Bershah, Edfu and Thebes, and in the Karnak temple (Schiegl et al. 1989; EI Goresy et al. in preparation).

Brown: jarosite and copper arsenate

The first of these is an in situ product of the devitrification and subsequent weathering of the potassium-and iron-rich glass pigment. The copper arsenate is a weathering product of arsenical residues in the glass phase of Egyptian Blue, in monuments erected between the period of the Old Kingdom and the end of the Second Intermediate period (see section on Egyptian Blue, above).

CHRONOLOGICAL EVOLUTION OF ANCIENT EGYPTIAN PIGMENTS

The chronological evolution of ancient Egyptian painting materials and Egyptian blue faience from the FIfth Dynasty until the Roman period is shown in the accompanying chart (Table 3). As we shall see below, distinct natural and synthetic pigments first emerged at the beginning of the New Kingdom, specifically during the reign of Tuthmosis III.

CHRONOLOGICAL EVOLUTION OF NATURAL PIGMENTS

The chronology of the natural pigments offers clues for distinguishing domestic from imported materials. The calcium sulphates (gypsum and anhydrite), the calcium carbonates (limestone or chalk) and ochre were clearly used without interruption from the Old Kingdom (and probably from the Predynastic period) down to the Roman period. These materials were evidently accessible at all times, thus indicating that they are of domestic origin. By contrast, huntite, orpiment and realgar display different, but consistent, chronological patterns. Huntite and orpiment first appear in the Eighteenth Dynasty, specifically during the reign of Tuthmosis III, and probably as a result of this pharaoh encountering the natural resources of Mesopotamia during his military campaigns on the upper Euphrates. Realgar has been found only in the tomb of Tuthmosis IV. It is notable that these three pure pigments enjoyed exclusive use for the decoration of the royal sarcophagi of the pharaohs of the Eighteenth Dynasty (from the reign of Tuthmosis III). This may hint at the high status of these pigments as precious and expensive materials not accessible to commoners. It is also notable that the application of huntite in its pure form in royal tombs ends in the Twentieth Dynasty (Ramses VI). By contrast, orpiment has already stopped being used as a pure pigment in the decoration of royal sarcophagi after the reign of Ramses I, but reappears in the decoration of the sarcophagus of Ramses VI. A detailed survey of the New Kingdom royal sarcophagi in the royal tombs at Thebes indicates that orpiment was not used for the decoration of royal sarcophagi after Ramses VI. However, the pigment is encountered on wooden coffins in the later New Kingdom and the Late period. The reason for the shift of use of this pigment from royal sarcophagi to the wooden coffins of commoners is unknown. I consider the close similarity in the chronological patterns of use of orpiment and huntite as an indication not only that both were imported materials, but that they were also perhaps imported from the same area. Unfortunately, however, the original sources of these pigments remain unknown to us. The reports of isolated occurrences of huntite in the tomb of Antefoker (Jaksch 1985) and orpiment in the coffin of Djhutinakht (Terrace and Braziller 1968) do not fit into the chronological pattern as currently perceived, and thus need confirmation. However, if future studies should verify these two reports, then we would have to conclude that huntite and orpiment were already imported as early as the Middle Kingdom. Analysis of white and yellow pigments from contemporary monuments may also shed more light on this question.

CHRONOLOGICAL EVOLUTION OF SYNTHETIC PIGMENTS

The chronological pattern of use of synthetic painting materials gives a relatively coherent picture which reflects the technological development involved. The abundance of both the blue copper glass pigment and the brown (or green) potassium-and iron-bearing glass pigments reflects an almost identical chronological evolution. Both seem to be confined to the Old and Middle Kingdoms. The technology of their manufacture may have emerged from the blue Egyptian faience technology which was already known in the Early Dynastic period. Whether they continued in systematic use in decorations of the Second Intermediate period and the early Eighteenth Dynasty remains unknown (Schiegl et al. 1990; Schiegl 1991; El Goresy et al. in preparation). There is only one report of secondary jarosite, a typical weathering product of the brown (or green) potassium-and iron-bearing glass, from a wooden figurine of unknown provenance in the collection of the Roemer and Pelizaeus Museum in Hildesheim (Inventory No. 6003) (Schiegl et al. 1989). Although the figurine was assigned by Egyptologists to the Eighteenth Dynasty, I consider this dating highly questionable, if not outright erroneous, since the occurence of this glass type or its weathering product jarosite has not so far been encountered in any decoration of well dated monuments of the Eighteenth Dynasty. For purposes of comparison, the chronological evolution of blue Egyptian faience is also shown in the accompanying chart (Table 3).

Egyptian Blue was in continuous use from the Old Kingdom down to the Roman period. Its use contemporary with blue glass pigment in the Old and Middle Kingdoms may suggest that the manufacture of blue glass pigment perhaps predated the introduction (or import) of the Egyptian Blue technology. The simultaneous use of both may suggest either an overlapping period or the need for two different hues of blue.

The distributions of arsenic (As), tin (Sn) and lead (Pb) in the glass phase in Egyptian Blue offers a precise chronological scheme for bronze technology in ancient Egypt, which narrows the margin of uncertainty for the introduction of tin-lead bronze down to less than 12 years (see section on Egyptian Blue, above). Moreover, the distribution pattern of these relicts offers the possibility of strict parameters for the accurate dating of questionable monuments and decorated artefacts at the beginning of the New Kingdom (tin residues) and within the New Kingdom (lead in the glass phase).

The chronological pattern of Green Frit indicates initial manufacture at the beginning of the Eighteenth Dynasty. Its use is recorded in tombs built immediately after Egypt was freed from the Hyksos occupation. It is possible that its manufacture resulted from a transfer of technology. This question however, must remain unresolved until decisive evidence is found.

The tin (Sn) and lead (Pb) distribution patterns of Green Frit are identical to those of Egyptian Blue, thus indicating that the same copper-bearing ingredients were used for the manufacture of the two pigments.

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