| A glaze is a vitreous coating to a ceramic material | | | | thereof (according to their wishes). And they will |
| whose primary purposes include decoration or | | | | be given to drink there of a Cup (of Wine) mixed |
| protection. Glazes can be considered specialised | | | | with Zanjabil, A fountain there, called Salsabil" |
| forms of glass. Glazing is the process of coating | | | | (76:15-8). Lustre provided the right ingredients for |
| the piece with a thin layer of material that during | | | | producing such vessels in a cheaper and |
| firing forms the glass coating. Compositions are | | | | acceptable way as Islam prohibits the use of gold |
| varied but are usually a mixture of minerals which | | | | and silver vessels. This is not the first time we |
| generally, but not always, mature at | | | | see Muslim craftsmen try to imitate paradise |
| temperatures lowers than the body itself. Glaze | | | | themes. Similar approach was adopted in |
| can be important for functional earthenware | | | | architecture, gardening, and even carpet making. |
| vessels, which would otherwise be unsuitable for | | | | The technique involved preparing pigments by |
| holding liquids due to permeability. Glaze may be | | | | mixing silver or copper oxides with an earthy |
| applied by dusting it over the clay, spraying, | | | | vehicle such as ochre, and then vinegar or grape |
| dipping, trailing or brushing on a thin slurry of glaze | | | | juice were added as medium. This pigment is then |
| and water. Brushing tends not to give a very | | | | painted onto the glassy surface of the vessel, |
| even covering but can be effective as a | | | | which has been glazed and fired once. The vessel |
| decorative technique. To prevent the glazed | | | | is then fired for a second time in a reducing kiln, |
| article sticking to the kiln during firing either a small | | | | then the ochre is rubbed away. |
| part of the item is left unglazed or special | | | | Firing |
| refractory supports, spurs, are used as supports | | | | Firing is an essential stage in the manufacture of |
| which are removed and discarded after the firing. | | | | pottery, during which chemical and physical |
| Evolution of Glazing technique | | | | reactions occur which causes thematerial to be |
| The glazing technique was greatly developed by | | | | permanently altered. The process is carried out in |
| Muslim potters who first used and improved this | | | | a kiln. |
| old tradition. In their early days (8th century), | | | | Some clays and glazes are oxygen-sensitive, |
| potters of Samarra and Baghdad employed lead | | | | most notably those containing iron and copper, |
| glazes with relief designs, a technique which came | | | | and will change colour depending on the presence |
| down from the Romans who spread it in | | | | of oxygen during the firing. Kilns can either be |
| countries of the Mediterranean basin, including | | | | oxidized by opening a port to allow oxygen into |
| Egypt. The nature of these wares consisted | | | | the interior or reduced by closing off the kiln from |
| mostly of red earthenware on which the shiny | | | | outside air to attain colors as desired. |
| green or yellowish brown glazes were applied. | | | | A number of various firing techniques can be used |
| As they became more experienced, these | | | | in addition to normal glaze-firing. Most of these |
| potters introduced another glazing method, which | | | | involve heating the kiln to a high temperature and |
| they developed from attempting to imitate the | | | | then delivering an amount of dry chemical into the |
| popular white Chinese ceramics. In doing so, the | | | | kiln's interior. Sulphur is commonly used, as are |
| Muslim potters introduced tin oxides to lead glaze, | | | | various salts or ashes. Such substances will stick |
| giving it a white finish. Lane explained how and | | | | to pieces within the kiln and melt onto their |
| why these potters achieved this: "It was | | | | surfaces, often resulting in a mottled texture |
| impossible to reproduce the beautiful surface | | | | which has a distinctive "orange peel" feel. Colors |
| texture of these (Chinese ware) by using an | | | | generally depend on what chemical is added to |
| ordinary clear lead glaze over a white slip, and the | | | | the kiln. These techniques can have very unusual |
| Mesopotamian potters therefore hit on a device | | | | and frequently unexpected results whether used |
| used long before them by the Egyptians. Tin | | | | on an unglazed piece or in combination with normal |
| oxide was mixed with a modified form of lead | | | | glazing. |
| glaze, which by the suspended particles was | | | | Wood firing is another type of firing which |
| rendered perfectly opaque and white. When | | | | involves using wood, rather than gas or electricity |
| applied to a well purified yellow or pinkish clay, this | | | | as in most modern kilns, to heat the kiln's interior. |
| glaze achieved a most deceptive similarity to the | | | | An example of a wood fired kiln is the Chinese |
| T'ang porcelain. But fortunately the Baghdad | | | | Anagama, also adopted and used by Korean and |
| potters did not rest content as imitators. They | | | | Japanese potters. Wood firing is frequently |
| were tempted to paint on the fine white surface, | | | | time-consuming, as the kiln must be stoked for |
| using cobalt blue, copper green, manganese purple, | | | | days, but the pieces which emerge often have |
| and sometimes antimony yellow". (Lane, A. (1947) | | | | characteristic patches of orange color on the clay |
| `Early Islamic Pottery', Faber and Faber, London, | | | | itself, known as "blushing". |
| p.13). | | | | The Western adaptation of Raku firing, a |
| In a third stage, the Muslim potter attempted to | | | | traditional Japanese technique, has enjoyed a |
| produce a closer version of the golden and silver | | | | great deal of popularity due to its relative ease. |
| vessels of paradise described numerous times in | | | | The kiln is heated to a low temperature, usually |
| the Quran. In Surah 76, for example, Allah | | | | no higher than cone 06, and then ware is pulled |
| promises His devotees: "Enter ye the Garden, ye | | | | out of the kiln while still hot (using tongs, of |
| and your wives, in (beauty and) rejoicing. To | | | | course) and smothered in ashes, paper, or |
| them will be passed round, dishes and goblets of | | | | woodchips. This can be done in an enclosed |
| gold: there will be there all that the souls could | | | | container, which allows the supply of oxygen to |
| desire, all that their eyes could delight in: and ye | | | | be cut off and reduction to take place. The |
| shall abide therein (for eye). Such will be the | | | | finished products of this process are not suitable |
| Garden of which ye are made heirs for your | | | | for functional use, as the clay remains porous and |
| (good) deeds (in life). Ye shall have therein | | | | may have some toxic chemicals held within it as a |
| abundance of fruit, from which ye shall have | | | | result of burning the surrounding woodchips or |
| satisfaction ".(43:71-3). In Surah 43, the Exalted | | | | paper used to smother it. However, because of |
| reminds the believers: "And amongst them (the | | | | the low temperature, it is an extremely quick and |
| Devotees of Allah) will be passed round vessels | | | | easy technique to do, and the clay has a |
| of silver and goblets of crystal. Crystal-clear, | | | | distinctive black color. |
| made of silver: they will determine the measure | | | | |