Kaca berwarna

Pengeluaran kaca

Dari abad ke-10,11 yang lalu,ketika kaca yang kotor mula digunakan mengarcha seni,para pengusaha kilang kaca bersedia dan menyimpan persediaan siap bahan silika, produk penting dari pembuatan kaca. Glass was usually coloured by adding metallic oxides to the glass while in a molten state in a clay pot over a furnace. Glass coloured in this way was known as pot metal. Copper oxides were added to produce green, cobalt for blue, and gold was added to produce red glass. Much modern red glass is produced using ingredients less expensive than gold and giving a brighter red of a more vermilion shade.
Kaca silinder
This glass was collected from the pot into a molten ball and blown, while being continually manipulated until it formed a large cylindrical bottle shape of even diameter and wall-thickness. It was then cut open, laid flat and annealed to make it stable. This is the type of glass most commonly used for ancient stained glass windows. 
Kaca mahkota
This glass was partly blown into a hollow vessel, then put onto a revolving table which could be rapidly spun like a potter's wheel. The centrifugal force caused the molten material to flatten and spread outwards. It could then be cut into small sheets. This glass could be made coloured and used for stained glass windows, but is typically associated with small paned windows of 16th and 17th century houses. The concentric, curving ripples are characteristic of this process. The center of each piece of glass received less force during the spinning, and thus produced was a thicker piece. These centres were for the special effect created by their lumpy, refractive quality. They are known as bull's eyes and are feature of late 19th century domestic leadlight and are sometimes also used with cathedral glass or quarry glass in non-pictorial church windows of that date.
Kaca meja
This glass was produced by pouring molten glass onto a metal table and sometimes rolling it with a large metal cylinder. The glass thus produced is heavily textured by the reaction of the glass with the cold metal. Glass of this appearance is commercially produced and widely used today, under the name of cathedral glass, although it was not the type of glass favoured for stained glass in ancient cathedrals. It has been much used for lead lighting in churches in the 20th century. Modern glass made by this technique is often heavily patterned by the use of an engrave metal roller.
Flashed glass
Red pot metal glass was often undesirably dark in colour and prohibitively expensive. The method developed to produce red glass was called flashing. In this procedure, a semi-molten cylinder of clear glass was dipped into a pot of red glass so that the red glass formed a thin coating. The laminated glass thus formed was cut, flattened and heat annealed.
There are a number of advantages to this technique. It allows a variety in the depth of red ranging from very dark and almost opaque, through ruby red to pale and sometimes streaky red that was often used for thin border pieces. The other advantage was that the red of double-layered glass could be engraved or abraded to allow light to shine through the clear glass underneath. In the late Medieval period, this method was often employed to add rich patterns to the robes of Saints. The other advantage, much exploited by late Victorian and early 20th century artists, was that sheets could be flashed in which the depth of colour varied across the sheet. This was applied to a range of colours. Some stained glass studios, notably Lavers, Barraud and Westlake in England, made extensive use of large segments of irregularly flashed glass in robes and draperies. 
Modern production of traditional glass
There are a number of glass factories, notably in Germany, USA, England, France, Poland and Russia, which produce high quality glass by traditional methods. Such glass is produced primarily for the restoration of older windows from 1920s and before. The production of new windows in traditional Victorian, Arts and Crafts and early 20th century styles often uses traditional glass. Modern stained glass windows also often use a variety of these different types of glass, or employ commercially made glass.

Origins

Coloured glass has been produced since ancient times. Both the Egyptians and the Romans excelled at the manufacture of small coloured glass objects. The British Museum holds two of the finest Roman pieces, the Lycurgus Cup, which is a murky mustard colour but glows purple-red to transmitted light, and the Portland vase which is midnight blue, with a carved white overlay. 
In Early Christian churches of the 4th and 5th centuries there are many remaining windows which are filled with ornate patterns of thinly-sliced alabaster set into wooden frames, giving a stained-glass like effect. Evidence of stained glass windows in churches and monasteries within Britain can be found as early as the 7th century.  Benedict Biscop’s monasteries in Monkwearmouth and Jarrow have revealed hundreds of pieces of coloured glass and lead from as early as 680CE,, though there is no reason to believe Britain was a pioneer in the medium.  Stained glass was also used by Islamic architects in Southwest Asia. In the 8th century, the Muslim alchemist Jabir ibn Hayyan (Geber) scientifically described 46 original recipes for producing coloured glass in Kitab al-Durra al-Maknuna (The Book of the Hidden Pearl), in addition to which 12 recipes were inserted by al-Marrakishi in a later edition of the book. Jabir also described the production of high quality coloured glass cut into artificial gemstones.

The Renaissance and Reformation

In Europe, stained glass continued to be produced with the style evolving from the Gothic to the Classical style, which is widely represented in Germany, Belgium and the Netherlands, despite the rise of Protestantism. In France, much glass of this period was produced at the Limoges factory, and in Italy at Murano, where stained glass and faceted lead crystal are often coupled together in the same window.  Ultimately, the French Revolution brought about the neglect or destruction of many windows in France.
At the Reformation, in England large numbers of Medieval and Renaissance windows were smashed and replaced with plain glass. The Dissolution of the Monasteries under Henry VIII and the injunctions of Oliver Cromwell against "abused images" (the object of veneration) resulted in the loss of thousands of windows. Few remain undamaged; of them the windows in the private chapel at Hengrave Hall in Suffolk are among the finest. With the latter wave of destruction the traditional methods of working with stained glass died and were not to be rediscovered in England until the early 19th century. See Stained glass - British glass, 1811-1918 for more details.

Revival in Britain

The Catholic revival in England, gaining force in the early 19th century, with its renewed interest in the medieval church brought a revival of church building in the Gothic style, claimed by John Ruskin to be "the true Catholic style". The architectural movement was led by Augustus Welby Pugin. Many new churches were planted in large towns and many old churches were restored. This brought about a great demand for the revival of the art of stained glass window making. 
Among the earliest 19th century English manufacturers and designers are William Warrington and John Hardman of Birmingham whose nephew, John Hardman Powell, who had a commercial eye and exhibited works at the Philadelphia Exhibition of 1873, influencing stained glass in the United States of America. Other manufacturers include William Wailes, Ward and Hughes, Clayton and Bell, Heaton, Butler and Bayne and Charles Eamer Kempe. A Scottish designer, Daniel Cottier, opened firms in Australia and the US.

Revival in France

In France there was a greater continuity of stained glass production than in England. In the early 19th century most stained glass was made of large panes that were extensively painted and fired, the designs often being copied directly from oil paintings by famous artists. In 1824 the Sevres Porcelain factory began producing stained glass to supply the increasing demand.  
In France many churches and cathedrals suffered despoilation during the French Revolution. During the 19th century a great number of churches were restored by Viollet-le-Duc. Many of France's finest ancient windows were restored at this time. From 1839 onwards much stained glass was produced that very closely imitates medieval glass, both in the artwork and in the nature of the glass itself. The pioneers were Henri Gèrente and Andre Lusson. 
Other glass was designed in a more Classical manner, and characterised by the brilliant cerulean colour of the blue backgrounds (as against the purple-blue of the glass of Chartres) and the use of pink and mauve glass.

Revival in Europe

During the mid to late 19th century, many of Germany's ancient buildings were restored, and some, such as Cologne Cathedral were completed in the medieval style. There was a great demand for stained glass. The designs for many windows were based directly on the work of famous engravers such as Albrecht Durer. Original designs often imitate this style. Much 19th century German glass has large sections of painted detail rather than outlines and details dependent on the lead. The Royal Bavarian Glass painting Studio was founded by Ludwig I in 1827.  A major firm was Mayer of Munich which commenced glass production in 1860, and is still operating as Franz Mayer of Munich, Inc.. German stained glass found a market across Europe, in America and Australia. Stained glass studios were also founded in Italy and Belgium at this time.

Innovations in the United States

Notable American practitioners include John La Farge (1835-1910) who invented opalescent glass and for which he received a US patent February 24, 1880, and Louis Comfort Tiffany (1848-1933), who received several patents for variations of the same opalescent process in November of the same year and is believed to have invented the copper foil method as an alternative to lead, and used it extensively in windows, lamps and other decorations.

Innovations in Britain and Europe

Among the most innovative English designers were the Pre-Raphaelites, William Morris (1834-1898) and Edward Burne-Jones (1833-1898), whose work heralds Art Nouveau. 
Art Nouveau or Belle Epoch stained glass design flourished in France, and Eastern Europe, where it can be identified by the use of curvings sinous lines in the lead, and swirling motifs. In France it is seen in the work of Francis Chigot of Limoges. In Britain it appears in the refined and formal leadlight designs of Charles Rennie Macintosh.

Twentieth century

Many 19th century firms failed early in the twentieth century as the Gothic movement had been superseded by newer styles. At the same time there were also some interesting developments where stained glass artists took studios in shared facilities. Examples include the Glass House in London set up by Mary Lowndes and A.J. Drury and An Túr Gloine in Dublin, which was run by Sarah Purser.
A revival occurred in the middle of the century because of the desire to restore the thousands of church windows throughout Europe, destroyed as a result of bombing during the World War II. German artists led the way. Much work of the period is mundane and often was not made by its designers but industrially produced. 
Other artists sought to transform an ancient art form into a contemporary one, sometimes using only traditional techniques but often exploring the medium of glass in different ways and in combination with different materials. The use of slab glass set in concrete was another 20th century innovation. Gemmail glass, developed in 1936, by the French artist Jean Crotti, is a type of stained glass where the pieces of glass that are adjacent to each other overlap allowing for a greater diversity and subtlety of colour.   
Among the early well-known 20th century artists who experimented with stained glass as an Abstract art form were Theo van Doesburg and Piet Mondrian. In the 1960s and 70s the Expressionist painter Marc Chagall produced designs for many stained glass windows that are intensely coloured and crammed with symbolic details. Important 20th century stained glass artists include Douglas Strachan, Ervin Bossanyi, Louis Davis,Wilhelmina Geddes, Karl Parsons, Patrick Reyntiens, Ludwig Schaffrath, Johannes Shreiter,  Judith Schaechter, Paul Woodroffe, Jean René Bazaine at Saint Séverin and the Loire Studio of Gabriel Loire at Chartres. The Luxus Keibel studio in Mexico specialises in domestic stained glass in both contemporary and 19th century styles. The west windows of Manchester cathedral in England by Tony Hollaway are some of the most notable examples of symbolic work.  
In the US, there is a 100-year-old trade organization, The Stained Glass Association of America, whose purpose is to function as a publicly recognized organization to assure survival of the craft by offering guidelines, instruction and training to craftspersons. The SGAA also sees its role as defending and protecting its craft against regulations that might restrict its freedom as an architectural art form. The current president is B. Gunar Gruenke of the Conrad Schmitt Studios. Today there are academic establishments that teach the traditional skills. One of these is Florida State University's Master Craftsman Program who recently completed a 30 ft high stained-glass windows installed in Bobby Bowden Field at Doak Campbell Stadium.