Art of Islamic metal
The art of metal out of ground of Islam is a major art, considered often as the most luxurious possible production. Thus, if metal can be produced for large silent partners (emirs, large commercial) as for the Souk, it is always expensive that which buys it, because of materials used. Metal works are in general movable objects, more rarely religious, except with regard to the keys of the Kaaba. There exist also architectural metals, but the scientific weapons and objects do not concern this field, because the techniques employed are often very different.
Knowledge of Islamic metal
Metal is a material which can be recycled, and noble metal recoveries were not rare during the history of the Islamic world. This is why our knowledge of those with regard to the first centuries of Islam is rather fragmentary. The objects out of alloy are studied often better. Moreover, it should be known that metals that one currently knows are often deteriorated, either because they remained a long time in the ground, or because they were cleaned and patinated by their owners.
The knowledge of the art of metal is based on several sources: archaeological excavations, objects collected (starting from XII-XIIIe century) in the East and occident, and the writings historiques.
The objects found in excavations offer several advantages, like that of a stratigraphic dating, but it in bad condition, are often corroded or fragmentary. At all events, the objects in themselves can learn much, by chemical analyzes, signatures, mentions of workshops or places of production. However, these inscriptions are rather rare, not only because the workshops were family, sometimes itinerant, but especially because work was divided and specialized. Thus, the engraver ( Al-naqqash ) was not always the same person as the Dinandier, which formatted the part. Extremely precise specializations existed sometimes, between the manufacturers of buckets, candlesticks, etc the written sources, as for them, can offer several types of information: production centres, types of objects, orders specific, etc
Materials and alloys
A metal is defined thus by a whole of mechanical properties and physical: solidity, the glare, opacity, deformability. These characteristics vary according to metals and from alloys used.
Pure metals
The metals used in the Islamic world are the Or, the
money, the Cuivre, the
tin, the
Zinc, the Plomb and the Fer, and come for the majority from mines from the
Khorassan.
Gold is a metal inalterable and ductile, which melts at high temperature (1064°C), and is presented at the native state in the form of nuggets and in rocks (seams). It requires to be allied to at least money 5% to be yellow. Pure gold is soft, and must be reinforced by the addition of other metals, like the money and copper. One extracts it in
Arabia, in
Central Asia, in the south of the
Spain and in
Egypt, but it can also be imported
Mali and
Sudan. The objects out of gold are rare, but it is frequently employed for the incrustations of other metals.
The money is also a very malleable white metal, very fragile (corrosion), whose melting point is around 960°C. One seldom finds it in a native state: it is in general combined with sulfur, lead or antimony. The money mines are rather numerous in the Islamic world, in Khorassan, with the
Ferghana, in the
Fars and the south of Spain. A shortage however took place between XIe and XIIIe century, as various historical sources attest some.
Copper is very much used in Islamic art. Soft, fragile metal (corrosion in Green of gray) it is present at the native state and has a red color then. Its melting point is at the neighborhoods of 1048°C. One abundantly finds it Islamic in everyone, in Central Asia,
Azerbaïdjan,
Arménie, Jezirah, with the
Morocco and in Egypt.
Flux at very low temperature (327°C), lead is mainly used in alloys at base coppers to lower the melting point of it. Of gray-bluish color, there does not exist in a native state, and must be extracted by netting. Slackness and malleable, one extracts it in the area from
Balkh, in
Anatolia, Jezirah,
Andalusia and
Sicily. It is possible also that it was the object of imports.
Like lead, tin melts at very low temperature (232°C), and is thus used with same knowledge in alloys at base coppers. It increases the facility of moulding, but has also a hardening action. One meets it in alluvia, but it must be extracted by netting. Very white and malleable, it is used sometimes for the coating as alloy parts: it is the
tinning. Until the 14th century, one imports it
Southeast Asia, then of
Great Britain.
Sometimes zinc is used to create parts, in particular at the time Safavide, but it is also used as alloy element at base coppers. Of white color, it is extremely breaking cold, but malleable with 100-150°C. Its melting point is at the access of 420°C. Coming from the mines of
Kerman and
Spain, it is extracted from the ores by netting. The insulation of pure zinc is an Indian invention of the 15th century.
Almost ever used in Islam in its pure form, iron is a metal of color white-gray which melts with 1530°C. The important layers are in Jezirah, in Fars, towards Kirman, in the Maghreb, in Sicily and in Khorassan. The keys of the kaaba are sometimes produced in this metal, like that preserved at Louvre, of the period mamelouke.
Alloys
There exist binary alloyings (two components), ternary (three components), even quaternary (four components), which all correspond in a very specific metallurgical state:
Bronze is a binary alloying, composed of copper and tin. Almost impossible to identify with the naked eye, its color varies according to the quantity of tin: if this one is lower than 10%, metal is red, towards 10%, it takes a pink color gilded, to 15%, it is frankly gilded and between 20 and 40%, one arrives at a production of
bronzes white , of color money or pale yellow. The quantity of tin exploits also much the plasticity of alloy: thus, white bronze is very seldom used because it is breakable like glass; on the other hand, it sounds very well, and reflects much the light once polished. It is used for mirrors and crockery in the world Iranian of, and definitively abandoned at the 13th century
Brass, as bronze, is a binary alloying which combines copper and zinc. Very difficult to distinguish from bronze, it varies red with the yellow gilded according to the proportion of zinc.
The ternary and quaternary alloys use the copper alloyed with tin and/or zinc and/or lead, in variable proportions. Metals of the
Khorassan, known as " Saljukides ", are frequently out of quaternary alloy, while those of the Mamelukes use a ternary alloy in general.
Steel is a carbon and iron alloy, which is used in art only at late periods, at the Othoman Qajars and the
.
The bidri is specific to the Indian world. This alloy containing zinc (at least 87%) of lead, copper and tin appeared at the 17th century with
Bîdar. It is about the only alloy whose base is not copper. The objects are moulded, polished, then rubbed with copper sulfate, which blackens metal. Brass and money incrustations, more rarely of gold, are then added to him: they can be " with fleur" or in relief on a layer of lead (speciality of the town of
Lucknow). Then, the craftsman applies a paste made up of ammonium chloride, of nitrate of potassium and sodium chloride, which blackens only alloy. The object is washed, then rubbed with oil, which still accentuates the depth of the black.
Techniques of working
There exist two great techniques of working of the objects out of metal.
Moulding
- For the parts relatively punts, the Fonte with sand is the average privileged person. It acts - schematically to print in sand, inside metal containers, the two sides of the wanted part, then to run metal there. The mould is not broken, allowing the cast iron of several identical parts. This technique was introduced in Iran, as from the 11th century, and was useful in particular for mirrors
-
For volumes, one generally prefers to use part moulds. The principle in is relatively simple: one carries out a wax model of the object, which one recovers of clay. Once dries, this one is cut out and the removed wax heart. The moulding takes place then in several parts, which is simpler, then the object is assembled by a welding with tin. This technique also makes it possible not to destroy the mould.
-
Sometimes, one employs also the technique of the Fonte to lost wax, with a mould in only one part, which is broken after casting and cannot thus be re-used.
Hammering
During hammering, the dinandier works a metal sheeting cold. This one is hammered on anvils of forms and sizes various with various hammers, to take the desired form. This type of work also causes to weaken metal and to make it breakable, and thus requires to heat work with regular intervals. The parts obtained by hammering are sometimes extremely complex, with strong reliefs.
An alternative is embossing on lathe. The craftsman first of all makes a wood heart which affects the general form to obtain; this element is then fixed on an axis, and the metal disc is pushed back against the form wished by means of a steel tool assembled on a large handle while the turn is actuated. This method, which is used only as from the 13th century, is simpler, but requires a greater physical force. During this work, the workman is maintained by a broad strap against the turn in order to facilitate this work of force. The use of the turn also makes it possible to polish surfaces.
Techniques of decoration
Without material addition
It is about a decoration carried out thanks to punches, in hollow or relief, and also known for this reason under the name of Poinçonnage. The decorations created exploit the repetition of the same reason, like the Ocelle S, for example.
During engraving, the artist tackles the surface of metal using a Ciseau to be engraved or of Gravoir S, if it wishes reasons different from simple grooves. Engraving is in general used on not-noble materials (neither but, nor money), because it removes matter, contrary to the Incision.
The openwork is done cold, by boring the sheet with a borer; many reasons (lattice, penmanship, figurations) can be created. This technique, which existed well before Islam, was employed from time immemorial for the Islamic period; it makes it possible to reduce the weight of a part and to let pass the light. Lamps of metal mosque, openwork panels for the doors, burn-perfumes, the openwork objects have various uses.
The decoration with pushed back is obtained by hammering with a bent stem of the back of a metal plate, cold. The relief obtained can be extremely detailed and deep.
With material addition
The niel is a black element resulting from the sulphurization of the money and gilded money. This state is obtained simply while passing from water on the parts intended to become dark. This technique exists out of Al-Andalus as from the 10th century and Iran hundred years later about.
Out of ground of Islam, gilding is made with the sheet on money, and does not have to be confused with the incrustations or the tombak.
Othoman technique, the tombak was already practiced in the Byzantine Empire, but its origins are badly known. The name derives from the word " tambaga" , namely " cuivre" into Malayan. It is about a technique making it possible to gild copper copper and alloys with a mercury and gold amalgam. The alloy or copper part is first of all cleaned with the acid before being whitewashed with the brush of the amalgam of gold and mercury and heated. Then, the part is polished with a paste made up of wax and metallic oxides, before being heated last once.
The noble metal incrustation (gold, money and red copper) in a metal alloy can be realized in nets or plates. The first stage consists in engraving metal according to the edges of the incrustation, then, if it is about an important surface, has to give him a certain irregularity so that the plates hold better. It is then necessary to deposit the wire or the plate of metal in the hollows envisaged for this purpose and to close again metal on the sides. Sometimes, a black paste is added (not to be confused with the niel) which makes it possible to raise contrast.
The incrustation was born in Iran at the 12th century, and introduced a revolution into the art of metal: polychromy thus obtained gave birth to true a " painting on métal" , and allowed this art to affirm itself. The craftsmen regarded themselves more as artists, as the multiplication of the signatures proves it. The diffusion of this technique in direction of the the Middle East was not made wait, and the art of encrusted metal reached its apogee in Egypt mamelouke. The incrustations decline as from the 15th century, in Egypt as in Iran, where it stop completely at the beginning of the Safavide period. A revival takes place at the time qajare.
The incrustations are very fragile, and many objects underwent scalings, in order to recover invaluable materials.
More
See too
- Baptistry of saint Louis
- Islamic Sciences and technology
- Damascening (in Syria, and in Tolède in Al-Andalus)