Zellige (Arabic: الزليج‎; also zelige or zellij) is mosaic tilework made from individually chiseled geometric tiles set into a plaster base. This form of Islamic art is one of the main characteristics of Moroccan architecture. It consists of geometrically patterned mosaics, used to ornament walls, ceilings, fountains, floors, pools and tables.

History
The Moorish art of zellige flourished during the Hispano-Moresque period (Azulejo) of the Maghreb and the area known as Al-Andalus (modern day Spain) between 711-1492. The technique was highly developed during the Nasrid dynasty and Merinid dynasty who gave it more importance around the 14th century and introduced blue, green and yellow colours. Red was added in the 17th century. The old enamels with the natural colours were used until the beginning of the 20th century and the colours had probably not evolved much since the period of Merinids. The cities of Fes and Meknes in Morocco, remain the centers of this art.

Patrons of the art used zellige historically to decorate their homes as a statement of luxury and the sophistication of the inhabitants. Zellige is typically a series of patterns utilizing colourful geometric patterns. This framework of expression arose from the need of Islamic artists to create spatial decorations that avoided depictions of living things, consistent with the teachings of Islamic law.

Use
The zelliges are used to cover the walls, and sometimes also the floors. The tiles used for the floors have a thickness of approximately two centimeters. Sometimes square tiles of 10 cm on each side are used with the corners cut to combine them with smaller pieces of colors. The bejmat is also used to decorate the floors, rectangular tiles of about 12 by 14 cm, generally interleaved in a V shape.

Colors
Nowadays, the chromatic palette of zelliges is very rich, which allows a great number of combinations:

The white base color of the enamel is obtained by covering the clay pieces first with calcina (khfîf) and with siliceous sand in an aqueous solution. Calcium 4 is a mixture of tin (15 parts) and lead (100 parts), calcined in the furnace to obtain oxides, and then ground in a mill by the potters.
For a purer white the proportion of tin is increased.
Blue is obtained from blue enamel powder (brâya, ‘elja) imported from other countries. It is an artificial color made by melting natural cobalt arsenide, previously burned to give cobalt oxide, with quartz and potassium. Nowadays, enamel is imported to obtain a more vivid color than cobalt in southern Morocco.
Brown is obtained by local minerals such as oligisto or manganese (moghnâsîya kahla). According to the presence or not of manganese, it may present violet tones or approach the color black.
Yellow comes from local ferrous minerals that appear in mixtures such as limonite or stibnite (natural antimony sulfide).
Green is the result of adding to the white enamel copper oxide (prepared by the potters from the remains of red covers purchased from the latoneros) or from calcosine (natural copper sulphide)
Red and orange are new colors made from imported synthetic pigments that began to be used in the Maghreb in the 17th century.

Clays for Zellige
Fez and Meknes in Morocco are still the production centers for zellige tiles due to the Miocene grey clay of Fez. The clay from this region is primarily composed of Kaolinite. For Fez and Meknes, the clay composition is 2-56% clay minerals, calcite 3-29%. Meriam El Ouahabi states that:

From the other sites (Meknes, Fes, Salé and Safi), the clay mineral composition shows besides kaolinite the presence of illite, chlorite, smectite and traces of mixed layer illite/chlorite (Fig. 3). Meknes clays belong to illitic clays, characterized by illite (54 – 61%), kaolinite (11 – 43%), smectite (8 – 12%) and chlorite (6 – 19%) (Fig. 3). Fes clays have a homogeneous composition (Fig. 3) with illite (40 – 48%). and kaolinite (18 – 28%) as the most abundant clay minerals. Chlorite (12 – 15%) and smectite (9 – 12%) are generally present as small quantities. Mixed layer illite/chlorite is present in trace amounts in all the examined Fes clay materials.

Forms and trends
As the colour palette of the zellige tiles increased over the centuries, it became possible to multiply the compositions ad infinitum. The most current form of the zellige is a square. Other forms are possible: the octagon combined with a cabochon, a star, a cross, etc. It is then moulded with a thickness of approximately 2 centimetres. There are simple squares of 10 by 10 centimeters or with the corners cut to be combined with a coloured cabochon. To pave an area, bejmat, a paving stone of 15 by 5 centimetres approximately and 2 centimetres thick, can also be used.

“An encyclopedia could not contain the full array of complex, often individually varied patterns and the individually shaped, hand-cut tesserae, or furmah, found in zillij work. Star-based patterns are identified by their number of points—’itnashari for 12, ‘ishrini for 20, arba’ wa ‘ishrini for 24 and so on, but they are not necessarily named with exactitude. The so-called khamsini, for 50 points, and mi’ini, for 100, actually consist of 48 and 96 points respectively, because geometry requires that the number of points of any star in this sequence be divisible by six. (There are also sequences based on five and on eight.) Within a single star pattern, variations abound—by the mix of colors, the size of the furmah, and the complexity and size of interspacing elements such as strapping, braids, or “lanterns.” And then there are all the non-star patterns— honeycombs, webs, steps and shoulders, and checkerboards. The Alhambra’s interlocking zillij patterns were reportedly a source of inspiration for the tessellations of modern Dutch artist M.C. Escher.”

Themes often employ Kufic script, as it fits well with the geometry of the mosaic tiles, and patterns often culminate centrally in the Rub El Hizb. The tessellations in the mosaics are currently of interest in academic research in the mathematics of art.

These studies require expertise not only in the fields of mathematics, art and art history, but also of computer science, computer modelling and software engineering, all used for the Hassan II Mosque.

Islamic decoration and craftsmanship had a significant influence on Western art when Venetian merchants brought goods of many types back to Italy from the 14th century onwards.

Zellige craftsmanship
Zellige making is considered an art in itself. The art is transmitted from generation to generation by maâlems (master craftsmen). A long training starts at childhood to implant the required skills.

Assiduous attention to detail is needed when creating zellige. The small shapes (cut according to a precise radius gauge), painted and enamel covered pieces are then assembled in a geometrical structure as in a puzzle to form the completed mosaic. The process has not varied for a millennium, though conception and design has started using new technologies such as data processing.

Manufacture of zelliges 5
The first stage of manufacturing is the molding of clay (mzahri in Arabic). It follows the calibration and drying of the formed tile, then its first cooking. The tiles, about ten cm apart, are then enamelled and baked. Tiles of different colors are then cut into defined geometric shapes that allow them to be intertwined. This artisanal cut is made with a slicing hammer that reveals a fine edging of terracotta exposed on the perimeter of pieces of cut tiles (“tesselles”). The kassar is the craftsman responsible for cutting tile tiles. His sledge hammer is named manqach. After this first cut, the next step is the khallaçwhich consists in chamfering the tesserae by giving them regular stops. In Arabic is called ” mâalem ” the craftsman who designs geometric patterns, sometimes of great complexity. He is usually able to draw and assemble geometric tesserae from memory, and glue them directly onto the walls to decorate.

The fuel of the traditional ovens was palm leaves, large white thistles, and oleander branches.

The mâalem Alaoui in the middle of the xx th century revolutionized laying zelliges technique. At that time, decorative earthenware was no longer limited to sacred or intimate spaces but also decorated public monuments. The system designed by the Alaoui masalem allowed a faster and stronger installation. The zelliges did not rest one by one on the walls but by whole panels. From a plot on the ground, zelliges are placed upside down on black soap, sprinkled with stucco mixed with water. Then they are covered with a thick layer of mortar that holds everything. The royal commissions have given new life to zellige crafts (the Mohammed-V mausoleum in Rabat and the Hassan II mosquein Casablanca.

The delivery of the clay to the workshop is done with double bundles loaded with donkeys. The artisans crush the clay blocks and put them to soak in the ponds dug on the floor of the yard. The artisan goes down into the pit and triturates the clay with his hands to penetrate the water. The paste obtained is drained on the edges of the pit and then relegated en masse to a corner of the workshop. When it is drained, the clay is spread on the terraces for drying in the sun during the summer months. During the winter, employees glaze, cook and cut the tiles.

Chipping
The tiles and installed cutting in the paintings is considered one of the most important stages in the manufacture of Moroccan tiles and it derives its specificity Fbmsaad model, the manufacturer shall draw Berchem the latter on the box and tries to draw the largest possible number of pieces by entering a single axial lines in the other so do not waste raw material expensive given It is the product of long work. On a small table with a length of 40 cm, the manufacturer prepares it, which consists of simple materials (wages, often sanding and plastering). This table contains sharp and solid materials of iron or marble. The manufacturer puts the box on it and with the help of a sharp special iron hammer from the sides called ” Almqash” The cutting of the pre-painted shapes on the square The solid piece on the table ensures that the tiles do not break and the cracking process is easy The manufacturer moves the box in a way that makes it easier for him to follow the lines drawn on it and on the other hand he holds the hammer or hammer that breaks the box. The second cold phase of small pieces or what the craftsmen call ” sincerity ” These pieces are cooled in a slant to get a surface of cement when placed upside down.

Composition
Installation on two types of brushes or brushes, after cracking and sculpture Arranging pieces according to shape and color, vacuum manufacturerIt is placed one by one in an upside down “colored side down” on a smooth floor called the “board” which is drawn to guide the manufacturer in the process of creating the desired shape. This process is important because it contributes to the lack of omission and error so that sometimes similar to some shapes with different colors and can not be distinguished because the pieces upside down. The manufacturer inserts small pieces into each other to form the board. He works without seeing colors or following a line or circumference of a circle drawn on the ground. It depends only on his experience, skill and concentration. When the small pieces of glaze take their final shape and after the installation and the small pieces are collected on the “board”, the manufacturer brushes it with a mixture of plaster and cement, which combines and installs these pieces together.

Source From Wikipedia