I=:DG><>CHD;
ny attempt to research the origins of the other hand, won sodium chloride mainly rich clays favoured the alkaline glazes be- Aglazes leads to the Middle East. The fer- from the dried lake beds in Wadi El-Natrun cause their thermal expansion was close to tile regions that stretch around the Syrian/ in north western Egypt (Wenigwieser 1992). that of the glazes. But this only came into Mesopotamian desert in a great arc have gone Together with the Arabic word "natrun", this play after the transition to applying glazes – down in specialist literature as the "Fertile soda (in ancient Egyptian "neter") is the and to glazing clay at all. Crescent"1). It has this name because culti- source word "natron" 2). Inasmuch as glaze Thus geological circumstances alone led vation of the soil is possible without irriga- is linked to copper smelting, or an object was to differences between East and West. But in tion, solely through rainfall. Research into to glaze itself in a bed of flux, the chlorine both cases, the formation of glaze depended climatic conditions shows that in the second in salt was of importance to transport soda, on a reaction from the surface immediately half of the 5th millennium up to 4000 B.C., and copper as a colourant, to the surface below it. Just as in human evolution, a dif- the climate was wet, subsequently changing of the object, where the soda flux met the ferent character with a different outer ap- to a dry climate. Additionally, humanity had glass forming agent, silica, and thus formed pearance developed on the soil of the Far placed nature under great strain through a glaze, which was coloured with copper. East. Glazes evolved from differing initial deforestation (partly to fire ceramics) and Things did not proceed in this fashion cells with an absolutely infinite capacity for overgrazing by sheep and goats. The land in the Far East. Glazes came about there cell division. The glazes from the Far East dried out and centres of population moved through deposits of ash during firing. And were mixtures of various rocks like solidified from the fertile crescent, where elaborate because wood ash has a different composi- molten magma, earthy and stony in appear- ceramics had been produced in Samarra, Tell tion from the halophytes, and the clay also ance, usually matt and opaque, whereas the Arpachiye and Tell Halaf, to the so-called has a different composition from the quartz, Middle Eastern varieties were transparent river oases where irrigation was possible the origin and composition of glazes in the and had clear, brilliant colours. from rivers. This is familiar from Egypt, but Far East and the Middle East are different. it also applies to the land on the lower half The Asian glazes require a much higher ma- 8deeZgVcY\aVoZh of the Tigris and Euphrates. turing temperature than the Middle Eastern The climatic conditions are also relevant ones – a requirement that could be fulfilled On the basis of excavations in Tell as-Sau- to the extent that vegetation depends on because of the degree of forestation. The van on the Tigris, in Ali Kosh in northwest the distribution of humid and arid periods glazes produced from the various types of Iran and in Çatal Hüyük in eastern Anatolia, over the seasons. The borders of the Crescent wood ash and clay found in China are cal- all of which are in the Fertile Crescent, it is were determined in accordance with the cli- cium-aluminium silicates requiring tempera- assumed that copper-working skills and pot- mate data, where peripheral strips merged tures of 1200°C and more, which cannot be tery making went back to the early Neolithic with the surrounding desert, in which barley achieved in bonfire firings. Kilns are required period (6th millennium) (Wertime 1964). It and emmer wheat (or farro) could be cul- for this, but Neolithic kilns were not suit- did not spread as rapidly as the production tivated and where wild goats grazed along able. Thus the first glazes in China were only of ceramics and only gained greater signifi- side sheep. Precipitation in the humid cli- recorded between 1300 and 1028 B.C. (Med- cance in the 4th millennium. Initially, in- mate in the Crescent prevented sodium chlo- ley 1976). So in contrast to the Middle East, tensely coloured copper minerals like azur- ride migrating from the salty ground water glazes were always on clay. They were fired ite and malachite were heated to 800°C and to the surface through evaporation. In the in cross draught kilns, which superseded freed of impurities by forging. With further moist climate, ferns, reeds and mulberry horseshoe-shaped up-draught ones that had advances, temperatures of 1083°C were nec- trees could thrive, the ashes of which are spread all over China from the south, and essary to smelt copper, which in the early rich in potassium but low in sodium oxide. from there to the entire Far East. In contrast period of copper mining could certainly not Ferns are richest in potassium if they are to Far Eastern clays, those found on the Ara- be achieved, but this became standard dur- harvested at the height of their vegetation. bian plateau between the Taurus mountains ing the 4th millennium, when casting cop- But in arid regions, the evaporation of salty and the Arabian Gulf can only tolerate low per became widespread in mining areas. With ground water is greater than the precipita- temperatures because of their high lime con- such high temperatures, it became possible tion. In these desert regions, salt plants tent, melting to a formless lump at around to use ore with a low copper content. This thrive, known as halophytes, which absorb 1150°C. Up-draught kilns were in use eve- first had to be heated in an oxidising at- and store the chlorine rich sodium salt from rywhere in this region. They were possibly mosphere below the melting temperature of the soil. The ashes from these plants served fired with straw and oil, in the manner that the rock so that the ore would oxidise and as fluxes in the glazes. The Egyptians, on is traditional in Iraq today. And the lime- sulphur would be removed, and then in a +%%% *%%% )%%% (%%% '%%% &%%% % &%%% '%%% 7#8# 6#9# HVbVggVXZgVb^Xh B XdeeZgldg`^c\ B \aVoZhdcXdeeZg hbZai^c\[jgcVXZh ? ?VgbdXZgVb^Xh B =VhhjcVXZgVb^Xh B hiZVi^iZWZVYh7VYVg^ : XdeeZghbZai^c\ ? h^a^X^XXZgVb^Xh E [V^ZcXZi^aZh@ZgbV C XdeeZghbZai^c\ D \aVoZYiZggVXdiiV B \aVhhn[V^ZcXZ : >gdc6\Z : cZl6hhng^Vc\aVoZ B iZggVh^\^aaViV I edanX]gdbZaZVY\aVoZ B l]^iZ\aVoZ B 7V\]YVYajhigZ B ;Vi^b^Y^XajhigZ : hVai\aVoZ < XZbZciVi^dc^cFdb > L:I 9GN ::\nei>>gVc??dgYVcBBZhdediVb^V >gVf CCjW^V HjYVc DDbVcEEVaZhi^cZIIjh`Vcn< ( (( ( (( ( ( ( >oc^` ( ( ( ( ( ( (( ( ( ( ( ( ( ( ( (I^\g^h IVWg^o ( vViVa=n` ( ( ( @]VWjg ( IZaa=VaV[ ( IZaa6VcV C^cZkZ]IZaa6geVX]^nZ Fdb IZaa=VhhjcV Cjo^ ( ( :je]gViZh IZaaBViVggV?Vgbd ( ( HVbVggVIZaaVh"HVjkVc ( ( 7VWnadc IX]d\]VOVcW^a 6a^@dh] L69>C6IGJC 9:69H:6 :aDWZYJg ( ( A^h]i H>C6> ( L69>6G676 ( ( ( ( ( ( ( E:GH>6C ( G:9H:6 DB6C ;Zgi^aZ8gZhXZci g^kZgdVhZh lVY^h @ZgbV ( XdeeZgb^c^c\ 8a^bViZX]Vc\ZV[iZgi]ZaVhi>XZ6\Z V[iZg8#:#7gdd`h!¹8a^bViZi]gdj\]i]Z6\Zh¹#CZlNdg`&.,% >cXajY^c\VbVe l^i]i]Z;Zgi^aZ8gZhXZciVcYi]ZeaVXZhbZci^dcZY^ci]ZiZmi# >aajhigVi^dch/DaV[7gj]c second stage, the heated rocks were melted 40cm high copper smelting furnaces from but also in a more advanced technology, in a reducing atmosphere to form metallic the Early Bronze Age (3150-2000 B.C.). This "glass paste". In the pre-dynastic grave field copper and slag. This kind of two-stage fir- is because only in this period were furnaces in Naqada itself, which is younger than that ing was later employed in a remarkable anal- constructed of sandstone there, but before of El Badari, Petrie had already discovered ogy for glazes and glass made of sand and and afterwards crucibles were used. Very "enormous quantities of beads", without de- vegetable ash in Mesopotamia, so that at much later, in the 1st millennium B.C., the scribing them any more closely (Petrie et al. low temperature chlorine and sulphur could furnaces were made of ceramic material, but 1896). be removed from the ash; then at a higher there is no evidence of glaze deposits in Archaeological research was long con- temperature the ceramic object received its them. These are only to be expected where cerned with the glazed steatite beads from El glaze. But this too only occurred with the the appropriate geological conditions are Badari. Science tells us that steatite (a kind development of the technique of glaze ap- found, i.e. where sandstone is also present of magnesium silicate) is transformed into plication. in ores, which however was not the case protoenstatite when heated to over 900°C, For the smelting process of the ore, iron in Oman, Cyprus, southeastern Anatolia or releasing silica and melting with the other or manganese were added to lower the melt- northwest Iran (Hauptman et al. 1999). ingredients, forming a glassy compound ing temperature. But the most important ad- on cooling. However, the magnesium only ditive was wood, which was necessary as a I]ZhZXgZid[hiZVi^iZWZVYh melts with the silica to form magnesium fuel to achieve a reduction atmosphere: cop- silicate at a much higher temperature. But per occurs in chemical compounds in the ore In 1922, the excavator Guy Brunton with alkalis and an increased silica con- which require reduction during the smelting found steatite beads in El Badari on the tent, this can be achieved at lower tem- process to produce metallic copper. In the eastern edge of the Nile valley. These beads peratures, like those in firing clay. And in Fertile Crescent, wood from the native mul- were glazed, which could not be explained. two cases out of ten, glazes on steatite berry tree (the "sycomore" of the Bible, Ä" Anyone who believed that in the dim and beads in the Badari period correspond to XjhhnXdbdgjh, not to be confused with the distant past, a nomadic cowherd had burned these conditions; one of them even cor- British sycamore) or from various varieties halophytes in a sandpit somewhere in the responds to a eutectic at 867°C in the of the acacia was used. These types of char- desert soon saw this notion corrected by sci- system Na2O-MgO-SiO2. The glazes were coal introduced potassium as a flux. The ash entific research: the Badari culture around alkaline silicates, like the efflorescences on of the mulberry has on average 36.6% K2O, 4000 B.C., whence the beads originated, was the later Egyptian paste. But they only con- 6.6% Na2O and 14.2% Cl as well as 57.0 % a highly developed culture (Weiß 1994). In tained sodium and no potassium. If crude CaO, 5.8% MgO and 6.3% P2O5 with 8.8% El Badari in central Egypt, thin walled ce- oil was used as a fuel, no potassium from a SO3 (Montmollin 1976). In arid climatic ramics in a fine clay with a delicate grooved vegetable fuel can have been introduced. zones on the other hand, sodium chloride pattern have been found, as well as bowls The question was thus how these glazes that migrated upwards from the ground wa- and mugs with black edges, known as black came about. Studies with the electron mi- ter is present not only in plants but also in topped ware with black reduced iron rims, croscope or the mass spectroscope showed porous rocks. The ashes of eight different which were burnished and may have been that they were caused by cementation3), halophytes analysed by H. Brill show values pushed upside down into the ground during i.e. in firings to 900°C in a bed of powdered of between 21.3 and 42.5% Na2O, 4.59 and firing to exclude oxygen and make them turn alkali, chlorine and copper. Sodium and cop- 17.2% K2O, 1.98 and 52.08% Cl as well as black. per penetrated the steatite to a depth of 3.50 – 17.7% CaO, 4.01 – 13.3% MgO, 1 – By 6000 B.C., 850°-1050°C had been 100 µm (which contains approx. 70% SiO2 2% SiO2, approx. 1% P2O5 and 0.77 – 4.74% reached in Jarmo, Mesopotamia, and in and 30% MgO, released at around 900°C), SO3 (Brill 1970). Major differences have 5500 B.C. in Samarra and later in 4500 B.C. forming a magnesium rich, glassy contact been detected in the salts in soda lakes. In in Ur, 1050°-1150°C were reached (Tite et zone in which forsterite crystals (Mg2SiO4) fourteen samples from Wadi Natrun, sodium al. 1975). The temperatures were estimated are embedded in a glassy matrix (Tite et al. carbonate (soda) and bicarbonate (NaHCO3) on the basis of changes in length of samples 1989). Analyses of the Badari glazes showed predominate, and in only four of these cases on reheating and from the transformation or 5.4 – 16.8% Na20, 11 – 15% CuO and 4.3 did sodium chloride reach more than 20%, formation of mineral phases, such as the for- – 30% MgO as well as 60 % SiO2 and 4.3 otherwise only being present at a low level, mation of diopsides (CaMgSi2O6) in the clay – 30.0% MgO, 0.6 – 3.3% CaO and 0.2 – to as little as 1.9%. On the other hand, sam- body from 850°C (Riederer 1988). 2.5% Al2O3, but no K2O. With beads made ples from El Kab south of Badari contained The findings from Badari give evidence of of carnelian and jasper (both SiO2), alkali as much as 57.3% sodium chloride. Potas- great experimentation. Various copper min- and copper both penetrated the surface but sium was not found anywhere, but sodium erals – oxides or sulphides, or ones contain- not so deeply. The higher the copper content sulphate (Glauber's salt or hVab^gVW^a^h) was ing antimony, arsenic or lead, were exposed and the higher the temperature, the greater present everywhere to some extent (Lucas to fire to obtain copper for implements or the depth of penetration and the stronger 1962). For various uses, especially mummifi- weapons. And for the production of beads, the colour. cation, the Egyptians had to be able to dis- all kinds of rock were fired: steatite, serpen- Scientific research tells us beads were tinguish between the various deposits. tine, limestone, alabaster, jasper, slate, ob- widely used in the ancient Middle East as Egypt and the Middle East were supplied sidian and carnelian (Brunton et al., 1928). amulets to ward off magic and demons. Es- with copper from the deposits in the Sinai These findings indicate that beads really pecially beads that had gone through fire peninsula from the 4th millennium on- were produced in Badari. It would have could be regarded as magical objects that wards. There were also smaller deposits in made sense to heat steatite, which is soft, transferred their powers to the wearer. the deserts to the west of the Red Sea or in because it becomes harder in the process. Reflection on production methods ex- Wadi Araba between the Red and the Dead Further evidence of local bead production cludes the possibility of the chance dis- Seas. Whereas crucibles for smelting cop- (which the excavator doubted) is the fact covery of glaze in El Badari. Glazing must per from the early days of metallurgy in the that large quantities of beads were found in have been intentional – in a bed of sodi- 5th millennium in Iran showed no traces of the subsequent Naqada culture (3700-2900 um chloride by cementation. The fact that glaze, greenish to bluish glazes have been B.C.), not only made of various other kinds glazes contained sodium oxide as their found on the sandstone brickwork of the of rock such as porphyry, basalt or marble, only flux indicates that soda will have had to be brought from soda lakes, which religious belief may have been involved in reminds us of El Kab. If the glazes had its origins, as in vegetable offerings (for contained potassium, the ash of a soda which there is evidence in Babylon) salt plant would have been used as a flux. Ste- was added to the fire rising to the gods, in atite too must have been brought from far the same way as people add salt to their away. own food to lend it savour. It would be Thus the assumption that someone may rather a neat idea to see glaze as a re- have set fire to a soda plant in a sand pit, ward of the gods. All of this can never be observing the formation of a glaze may be knowledge, it can only ever remain belief. discounted because of the absence of po- For this, halophytes would have been un- tassium oxide in the glaze. As to the trans- suitable, but not the arid salt, which was fer of experience from copper metallurgy ;ZbVaZ Ä\jgZ VcY ine^XVa ÄcZan \gddkZY XZgVb^Xh VcY ready for use from the soda lakes and be- or from Egyptian paste, scientists who WaVX` ideeZY XZgVb^Xh ine^XVa d[ :a 7VYVg^! Vh lZaa Vh side the Khabur River. Standard clay ware V jc^fjZ ija^e"h]VeZY WZV`Zg l^i] l]^iZ ^cXgjhiVi^dch! have studied these questions are not in l]^X]bVn]VkZWZZcigVchedgiZY[gdbZahZl]ZgZ#I]^h from the middle Khabur period is assumed agreement with regard to what came first XdjaYWZVh^\cd[igVYZa^c`h#7VYVg^eZg^dY)&%%"(,%% to have contained salt (Schneider et al. and what followed. The Badari period was 7#8# 9gVl^c\hV[iZg7gjcidc h&.'-ZmXVkVi^dcgZedgi # 2002). This would lend support to the as- between 4100 and 3800 B.C. Kind (1999) sumption that this salt was used before dates the beginnings of ore smelting at vegetable ash, which previous analyses 3700 and the first silicic ceramics (corre- also suggest. The key characteristic is the sponding to Egyptian paste) at 3100 B.C., absence of potassium. In Egypt, potas- i.e. both at a later date than the steatite sium oxide in glazes is first found on ste- beads in El Badari. Werthmann dates the atite objects in the New Kingdom. beginnings of alkali silicate glazes simul- The composition of the powder bed taneously with copper smelting, which did in Badari, which was probably only used not begin until 3900 B.C. Vettel (1999) intentionally for cementation at a later also estimates that stones were glazed as date, can only have been based on a "by-products of copper reduction firing". knowledge of the fluxing power of natu- Hauptmann and Klein (1999) date glazed 7dlaVcYkZhhZa[gV\bZci[gdbIZaaBViVggV +%%%·)-%% ral soda. That silica was also necessary for pearls much further back, "in Mesopota- 7#8# ^c=VhhjcVdgHVbVggVhinaZ#7di]VgZgZb^c^hXZci glaze formation need not necessarily have d[ÄcY^c\h^c:a7VYVg^/i]ZYZXdgVi^dcd[i]ZWdlad[ mia, perhaps far back in the 5th millen- i]Z\gddkZYkZhhZah!i]ZdgcVbZciVi^dcd[i]ZZY\Zdc been recognised at that point as silica is nium B.C.". They doubt the link to copper i]ZkZhhZa[gV\bZcid[i]Zija^eWZV`Zg YgVl^c\hV[iZg contained in steatite, and carnelian and metallurgy, pointing out that glaze forma- 7gV^YlddY h&.*'ZmXVkVi^dcgZedgi # jasper will hardly have been recognised as tion in smelting furnaces only appeared sources of silica. When it was seen that later, as the earliest findings of Egyptian glazes formed during copper smelting paste. In contrast, Moorey (1994) is of only on sandstone but not on ceramic was the opinion that alkali-lime silicates, i.e. there any evidence that it was important glazes, appeared in Mesopotamia as a re- what material the flux encountered. sult of the observation of glazing on lime- seems to confirm Hauptmann and Klein's From the second millennium B.C., clay stone slabs in the furnaces for smelting assumption that glazed beads in Mesopo- pots with lids were found in a kiln in copper. These uncertainties are unsurpris- tamia go back far into the fifth millen- Abydos (Nicholson 1998), of a kind that ing as question of the invention of glazes nium. From the evidence that in El Badari, favours cementation as chlorine would is not a central concern to archaeology. ceramics were found from Samarra and not have escaped into the atmosphere, Any findings are only by-products of ex- Hassuna, and from the assumption that instead transporting the sodium and cop- cavations, and it is often unclear whether the production of beads may have been per into the ware in an enclosed space. Egypt or Asia Minor has priority. The next for export, the conclusion may be drawn With the aid of such closed pots, even to- excavations can always completely change that glazed Badari beads may be seen day quartz rich so-called donkey beads are the picture. in relation to Mesopotamia. They would produced in Qom, using a vegetable ash Among the ceramics found in El Badari therefore have stood at the beginnings and firing them to approx 1000°C. In this a tulip-shaped vase untypical of this cul- of glaze development in Mesopotamia, process, quartz is transformed into cristo- ture stands out, which is without doubt which would have to be seen the result balite at 226°C. The resultant shrinkage painted ware in the Hassuna or Samarra of independent experiments without the in volume of 3% prevents crazing in the style. In 1948 (Braidwood et al. 1952), transfer of alien experience. Only the fir- alkaline glaze. The beads can be separat- Braidwood found stone beads in Tell Ma- ing of clay may thus be a possible form of ed from the powder after firing. They do tarra in the Fertile Crescent as well as a prior experience. And this was initially not not stick together because a transitional similar triangular pattern on the edge of conducted in kilns but in pits. There is no zone forms between the loose powder and a clay bowl. evidence of kilns in the Middle East before the solid bead which solidifies during the Hassuna ceramics extend from 6000 – the 4th millennium. melting processes and allows the bead 3600 B.C., overlapping the Samarra period The evidence can only support theories, to be removed with a glaze on all sides in the 5th millennium (4900 – 4300 B.C.). with which nothing is proved, but which (Berger 1999). This process was also used Tell Hassuna is not far to the south east at best are believable. Thus the mass pro- in Roman times, using copper filings for from Tell Matarra and north west to the duction of beads in Badari suggests a tem- colouring as Pliny the Elder noted in his Khabur River, where dry salt lakes are to poral intention at an advanced stage of cVijgVa^h]^hidg^V. be found. This period is so long before development; the origins should therefore copper smelting that there can have been not be sought here, just as the excavator no transfer of experience from it. This Brunton suggests. It is more likely that EVgi>>id[daadl I=:DG><>CHD; gdbZ[ÅdgZhXZcXZid\aVoZ been glazed in this manner during the The invention of the application of ;Veea^XVi^dc Middle Kingdom and could now be pro- glazes paved the way for lead glazes and duced in larger dimensions. And the prod- other variations. And the potential to vary It is known that in northern Mesopo- ucts were harder, because the flux (soda), glazes lead to a new quality in working tamia and northern Syria, potters added which formed the glassy matrix in the with glaze because the process of repeat- sand to their clay to "shorten" it, which body, remained in the core, thus lending ing traditional methods was superseded was not customary in Egypt (Peltenberg strength. The glazes that were applied by researching into the properties of in- 1971). It is thus not reasonable to assume contained tin, which implies the use of dividual substances in a way that is still that Egyptian paste, a process for which bronze filings for colour. This bronze must characteristic of glaze science today. efflorescence is characteristic, developed have contained lead as the glaze con- A new path of development opened up from ceramics. It was sand in conjunction tained 2% lead oxide as well as 1% tin for alkali silicate glaze in the first millen- with soda that formed a body in this case. oxide. They were also rich in quartz, and nium B.C., which was linked to glass tech- As soda is water soluble, it migrated to as sodium silicates they corresponded to nology. The cuneiform texts from Niniveh the surface on drying, where together with the efflorescence glazes found in Egyptian indicate that glass was made from a mix- the sand it formed a glaze on firing. But paste (Tite et al., 1989), which dominated ture of sand and plant ash in two stages. the migration of the flux is not depend- silicic ceramics in the New Kingdom in In the first phase, during which the chlo- ent on chlorine here; it is transported by Egypt with its efflorescence technology. rine and the sulphur were expelled, a frit evaporating water. The fired body is not It was important for society as a whole was created at low temperature that could very hard as the flux, which causes the because it represented a divine colour in a either be melted to form glass in a sec- body to harden, largely migrates to the precious material that along with gold was ond firing at a higher temperature or could surface zone. This efflorescence corres- even part of the pharaohs' regalia. be stuck to a quartz-rich body with plant ponds to salt rising to the surface from When it was discovered how to harden gum and then fired on to it. This glass was salty ground water to reach the roots of the loose sandy body to form a glassy not yet the kind that could be worked by plants and to be absorbed by porous rock faience in Lisht, 6 km south of Cairo in blowing, but it formed a viscous melt that in an arid climate. This was thus an imita- around 1700 B.C. (Lilyquist et al., 1993), could be used to make sand core glass or tion of a process in nature. by mixing a soda frit instead of soda with mosaics. The archaeologist Hedges found The invention of Egyptian paste is pos- the sand (Vandiver 1983), no soda migrat- glazed ceramics at this level of techno- ited for the upper Nile region in the 3rd ed to the surface during drying any more logical development at the same time as millennium. According to evidence from and the glaze had to be applied to the sand core glass for the first time in Nuzi Kerma in Nubia, the Nubians had achieved exterior. This method of glazing, which (present-day Yorghan Tepe) in northern great mastery in the art of this technique. has been found in addition to a thin ef- Mesopotamia (1982), west of Kirkuk, from Excavators have found cultic buildings florescence layer (Kühne 1999), proved the period between 1400 and 1350 B.C. with remarkable wall claddings made of to be superior as the glaze could be var- According to Wooley (1955), the oldest blue-glazed tiles and partly gilded Egyp- ied. Thus glazes over Egyptian paste have dated terracotta is from Tell Atchana, not tian paste tiles as well as lions 1.2mtr in been found in Malkata dating from the far from the Mediterranean coast in present width, and bed feet resembling the feet 15th century B.C. in blue, yellow, green day Turkey, and dates from the mid-15th of cattle and hippopotami, made of blue and red (Hayes, 1959), and later in Tell century B.C. Chemical analyses (Hedges glazed and black painted Egyptian paste el-Amarna in orange too. Frit porcelain 1982) from the Achaemenid, Parthian and (Bonnet 1996). This was all of better developed from glassy faience, a type of Sassanid periods (from 700 B.C. revealed quality than the Egyptian paste after the soft paste porcelain, which was made in glazes with the following boundary val- turmoil of the First Intermediate Period France after the Persian model under the ues: 6-8 % Na2O, 2.5-4 % K2O, 4-8 % CaO, at the beginning of the Middle Kingdom name of "Persian porcelain". It was then 2-4 % MgO, 2-3 Fe2O3, 4-8 % Al2O3 und (2040-1785). made in under the patronage of Louis XIV 65-75 % SiO2. After a phase diagram by The dependence of glaze formation on Saint Cloud, later in Sèvres, as pâte tendre Morey (1930), this ratio of alkali to earth the ceramic body, which is typical both artificielle. It then made its way to Co- alkalis and silicic acid needs a firing range of the cementation and the efflorescence penhagen as well as Rörstrand/Marieberg of 900°-1100°C. These glazes were ap- technique, only waned after the appear- in Sweden, and even today it is offered plied to a body with 16-17 % CaO, 5-6 % ance of the technique of applying glaze for sale as a soft paste porcelain body in MgO und 50 % SiO2, which corresponds mixtures. Steatite objects had already Limoges, for instance. to the lime-rich clays of the Middle East. GUSTAV WEISS FORUM Paths of development of glazes in the Western hemisphere The glaze that emerged from the arid desert regions of the Middle East during the Stone Age Developments in kiln technology and methods of kiln control in the 20th century made the transition possible from earthenware with its porous body to soft paste porcelain with a transparent glaze, (invented in 1790 as fritted porcelain or bone china e, In the 16th century, Turkish potters in Iznik invented a type of following the example of milk glass, which contained bone ash as fritware w with a combination of transparent lead and alkaline e an opacifi er). In comparison to hard paste porcelain, this saves glazes with underglaze brushwork on a white body, as a reaction energy. The fi ring temperature for bone china is 1255 – 1265°C. to blue-and-white Ming porcelain from China. In England this type In spite of its unprecedented potential, the development of glazes of ware was reinvented in 1740 as “creamware”, which pushed was restricted to the colours and effects of “art glazes” r in the faience from the market in Europe in the 18th and 19th century. fi eld of individually produced art. White glazed ceramics using a mixture of lead and tin and painted in the raw glaze came to Europe from Constantinopel via Venice and Faenza in the 14th century, during the Renaissance, and were known as “faience” { in Italy and “majolica“ } in Spain. In the w 16th / 17th centuries, 342 faience factories were set up in Europe. In 18th century, porcelain painting was adopted, with the colours from glass painting and the smooth white glaze, with the painting being fi red on in an extra fi ring (“onglaze faience” q). q Lead, which as a by-product of silver production was available in large quantities, made it possible to apply lead glaze I to any clay body as early as the 1st century B.C. This glaze spread to Europe. { } r Transparent lead glazes dominated ceramics into the 20th century. The temperature was the same as for the smelting of silver, i.e. 960°C. P The creative evolution of glazes in the Middle East continued with I original white, lea / tin glazes O, inspired by Chinese porcelain O and the lustre technique P. adopted from glassmaking. Y The Assyrians perfected the appliqué tech- nique and used coloured glazes made from a frit of sand and plant ash, using a two- T stage fi ring to decorate brick reliefs U “Glassy faience” evolved into “Persian porcelain” T in the 16 th cen- on their their palatial buildings in the 1st tury, leading to French soft paste porcelain Y in the 18 th century. and 2nd millennium B.C. Firings were to the melting point of copper, 1083°C. This “fritted porcelain“ is still in use today. U R To make a harder core that did not release its hardening fl ux to the surface, a mixture of sand and salt or the ash of salt plants (halo- phytes) was melted together to form a frit, and was then mixed with desert sand to form a core (“glassy faience“ R, 2nd millen- nium B.C.). The glaze now had to be applied on the exterior, but it still required a siliceous base (“siliceous“ or “quartz ceramics“). W E In the pre-pottery Neolithic Age (5th millennium B.C.), nomadic shep- In the same way as salty ground water evaporates upwards to the herds carved beads Q from easily worked stone to guard against surface in arid desert regions, sodium salt and salt leached from the magic and demons, as they had previously done with bone. These naturally lime rich desert sand migrated to the surface in a watery beads were self-glazing if they were heated in a pit together with the Q mixture as it dried on the surface and formed a glaze when exposed chlorine rich sodium salts from a salt lake (“cementation”). The stones to heat (“effl orescence“, 3rd millennium B.C.) The original glaze, had to contain silica, which is the case with steatite for example. The which was coloured Egyptian blue with copper, achieved other beads were coloured blue with a ground, copper-bearing rock. The splendid colours through other additives, and as “Egyptian paste“ temperature was 800 – 900°C. This technique is still in use for donkey E became part of the insignia of power and rank of the pharaohs. beads W in Iran. Illustration: Olaf Bruhn JULY / AUGUST 2009 .%7 #%2!-)#3 37 According to Hedges, glazes of this type ing with slight smoking. When the pieces glaze from Iznik from 1480 consisted of were in used unchanged over several mil- had cooled, they were scoured with damp 10.2 % Na2O, 1.1 % K2O and 22.0 % PbO lennia, into the 6th century A.D. (Hedges earth and then shone "like gold and spar- (information from the University of Iznik). et al., 1975). kled in the sun" (Sarre 1925). Underglaze painting made its appearance According to findings to date, the ear- Although lustre painting had been in Iran in the 13th century (Helmecke liest glazed bricks date from the 14-13th abandoned in Iraq towards the end of the 1999), before it spread to China in the centuries B.C. in Chogha Zanbil in Khuz- 10th century (Baghdad, Samarra or Basra late 13th century. Lead glazes survived all estan in the southwest of Iran (Peltenberg lustres), in Egypt (Fatimidic lustres), then over the world into the industrial age. It 1971), i.e. several centuries before the in Syria and Iran, it came to full flower in was even to be found in China in the Tang bricks in the Ishtar gate under Nebuchad- the 14th century, later falling into obscu- dynasty in the 7th century and in Japan in nezzar II (605-562). Thus the glazes on rity so that it had to be reinvented in the raku ceramics since their invention in the these bricks were not a contemporary in- 17th century (Shah Abbas lustre). Since Momoyama period in the 16th century. vention in Babylon; Babylonian craftsmen the 10th century, lustre ceramics had be- Glazes could not have been invented had had a high reputation as makers of come successful in Andalusia and from the if fluxes had not been found in nature polychrome glazed ceramics for genera- 14th century in Valencia too, spreading to that made the melting of the ingredients tions. Thirty years before Nebuchadnezzar, Castile in the 15th century (Burgos lustre) possible. From that point on, glazes be- Tiglat-Pileser III (762-722) and Sargon II and Aragon and Seville in the 17th centu- came a product of human skill and abil- (722-704) had deported Babylonians to ry (Wilson Frothingham 1951). It made its ity, knowledge, motivation and the desire northern Syria to inject life into glazed way to Italy in the 15th century (Deruta) for artistic and intellectual achievement. ceramics there. By this means, norhtern and was revived in England and Denmark These characteristics, which can be ex- Syria became the leading force in the pro- in the Art Nouveau period. The quartz frit pected of a person in the course of their duction of polychrome glazed ceramics in body was widespread throughout the Is- life, run parallel to the historical path of the last third of the 8th century B.C., and lamic world, and especially in Iran it was glazes. We are accustomed to see them in the influence of Neo-Assyria in the 8th-7th of finest quality (Helmecke 1999). In 1301, isolation. But they are part of a whole, centuries B.C spread as far as Susa in Iran Abul Qasim from Tabriz wrote in his Book the other part of which is the body they (Moorey 1994). Whereas Egyptian paste of Stones about the production of lustres lie on. It is like yin and yang. One deter- was losing its importance in the middle of and a throwable quartz frit body as well mines and complements the other, and a the first millennium B.C. and bronze had as the production of the frit from quartz part of otherness is present in both. They to make way for iron, quartz frit bodies and plant ash (Ritter et al., 1935) The go through history together. In the Far were reinvented for ornamental ceramics glaze was said to be as white as Chinese East, it was woodash and clay that formed in the early Ottoman period in Iraq and porcelain. Its white opacity came from a a glaze, in the West it was plant ash and in the 10th century B.C in Egypt (Helmke mixture of tin and lead melted together in sand. In China, the development of glazes 1999). an open iron pan. Until frits became com- was linked to the teachings of Confucius, In Iraq, variations in glazes for aesthe- mercially available in the West in the 20th in Japan it was the spirit of Zen. And the tic reasons came to a climax in the early century, nothing changed in the method glaze did not cover the body entirely, leav- Ottoman period, in the 9th century, when for producing frits for faience glazes. ing it visible as a yin symbol for the earth, Iraki potters were induced to imitate un- When insoluble lead replaced soluble which forms the basis of the spirit. In painted, white porcelain from China, espe- alkalis, the two-stage firing process with China, jade-coloured celadon glaze was a cially samples such as those which Harun the production of the frit in the first phase symbol of the life force in connection with Ar-Rashid had received as imperial gifts. and the glaze firing as the second, could the mysterious yang principle of the great The potters probably realised that nature be simplified to a single firing ("raw" glaze primal beginning of heaven and earth. In had not granted them the same conditions without frits). Even in the Middle Ages in Islam, the green to blue-green turquoise as those in China. With the means at their Europe, however, lead was not mixed with glaze was a symbol of life and heaven, as disposal and their traditional experience, clay, as later became customary, to form it had been in ancient Egypt, represented they created luxury ceramics that were far a glaze slurry with water that could be in the glazed tiles of the domes of mosques superior to standard pottery of the times. poured and which then adhered to the po- which simultaneously protected the mud It was particularly the white glaze that rous body, but it was dusted on to a coat- walls from the elements. The spirit that was developed further to make a tin glaze ing of a flour-based adhesive with copper determines all of life motivated technical based on the experience of earth alkali and brass filings. Heraclius reported on and artistic inventions that evolved from silicates from the Parthian period (250 this procedure in "De coloribus et arti- the observation of nature. B.C. – 226 A.D.). On this they painted bus Romanorum" in the 12th century (Ilg, with cobalt "like ink on snow". The Chi- 1873). Old potters in Switzerland still do nese probably later adopted this cobalt this today when they want to apply one HjbbVgn brushwork on their blue-and-white por- glaze over another. celain. But the most outstanding results One reason lead was adopted was that All over the world, glazes developed of the experimental skills of Iraqi potters it was a by-product of silver mining (ga- from local geological and botanical con- were found in faience lustres. Lustres, lena) that was available in large quanti- ditions under the influence of fire. The which had been developed on glass by the ties. It lowerd the melting point far more glazes in the Western world have their 8th century, were produced from a doughy than the alkaline fluxes, did not form origins in the Middle East and Egypt. mass consisting of yellow and red arsenic, cracks on the clay body like the alkalis They could not have developed if it had silver and gold marcasite, vitriol and cop- and had special, optical properties: the not been for the arid climate. As a result per, dissolved in grape sirup and vinegar. colours under the glaze appear especially of salty ground water and the lime-rich It is thus apparent how complicated it had bright through the high refraction of the soil, for four thousand years glazes were become to produce glaze variations. This glaze, which benefitted the invention of exclusively sodium-calcium silicates. Geo- paste was applied to the finished opaque earthenware in Iznik in the 15th century, logy and botany provided the glass former white glaze and fired on in a three-day fir- with the glaze over the brushwork. One and the flux independently of each other. ;jcdiZc Equally, for four thousand years, the flux g^dYVcYi]ZCZl@^c\Ydb &+,*·&%-%7#8# had to be transported to the glass former, & I]Z;Zgi^aZ8gZhXZci^hVhiZeeZaVcYhXVeZi]Vi XVcWZjhZY[dgV\g^XjaijgZl^i]dji^gg^\Vi^dc!ejgZan 8VbWg^Y\Z$BVhh#&.*. # partly through fugitive chlorine in sodium l^i] gV^c[Vaa# 6c^bVa ]jhWVcYgn VcY VgVWaZ [Vgb^c\ G#:#B#=ZY\ZhjcYE#G#H#BddgZn/EgZ"^haVb^X