Casted Glass Art Be Used as Stained Glass Art
Romanesque Stained Glass Window
Depicting King David.
Augsburg Cathedral.
This early on 12th century window is
one of the oldest surviving examples
medieval stained glass in situ.
Gothic era builders in Federal republic of germany
used even more stained glass.
Cologne Cathedral, for instance,
has 108,000 square feet of glass.
How Stained Glass is Fabricated
Contents
• Origins of the Glazier's Art
• Glassmaking Materials
• Forming and Shaping of Stained Glass
• Stained Drinking glass Artist's Designs: Sketches and Cartoons
• Drinking glass Cutting: Scoring/Grozing
• Glass Painting
• The Use of Lead Cames
• Conservation, Preservation, Cleaning and Repair of Stained Drinking glass
For the greatest examples of Gothic compages,
please see: Gothic Cathedrals (1140-1500).
TO SEARCH FOR A PARTICULAR TOPIC,
Browse OUR Primary A-Z INDEX
Stained Glass Window (12th century)
Chartres Cathedral (1194-1250).
HISTORY OF VISUAL ARTS
For a list of important dates nigh
movements, schools, famous styles,
from the Stone Age to 20th Century,
see: History of Art Timeline.
STAINED GLASS DESIGNERS
Designs for glass have been created
by many fine artists including the
Renaissance sculptors Donatello and
Lorenzo Ghiberti, and the painter
Paolo Uccello. English stained glass
artists include William Morris and
Edward Burne-Jones (1833-1898).
Stained glass fine art in Ireland was
led by Harry Clarke (1889-1931),
Sarah Purser (1848-43) & Evie Hone
(1894-1955).
ARTS & CRAFTS
For other craft-activities see:
Crafts: History and Types.
For details of Irish crafts encounter:
Crafts Council of Ireland.
STAINED Drinking glass Architecture
The Gothic style of architecture,
which dominated stained glass in
Europe (1200-1500), was connected
to the rising of cities and with them
urban populations & the cathedrals,
bishop and clergy that served them.
Oft members of powerful families
of the region, the clerics were highly
educated and keenly aware of issues
of art and architecture. They built
in the new Gothic way, tapping into
the economical development of the 13th
century: the only completely new style
since antiquity, Gothic architecture
developed with stained drinking glass as a
necessary construction element.
STAINED GLASS ICONOGRAPHY
Cathedrals shared a belief in
Christian rituals (including images)
that communicated both social and
religious meaning. In most regions
Church and state were linked to one
some other and peoples were ethnically
monolithic. Europe shared a single
cultural base of operations of biblical text. Despite
wide thematic unity, still, no
two artistic statements were ever
exactly alike. For instance, the birth
of Christ was an expected presence
on a Gothic sculptured portal and
each element of the story - the infant
in the manger, the shepherds, the
Magi and King Herod - was easily
recognizable. Their placement in
whatever given artistic interpretation,
all the same, differed according to the
local audience. For example, at
Notre-Dame Cathedral Paris,
inside walking distance of the royal
residence, the due west portal sculpture
emphasizes the Iii Kings, carving
in stone the conventionalities that a divinely
inspired monarch ruled France.
All art of the time, be it illuminated
gospel manuscripts, wall painting,
sculpture or metalwork, used similar
systems of interrelated imagery. The
unique power of these 'seen' truths,
was enhanced by the fact that the
vast majority of people saw images
only in church. Non until Johannes
Gutenberg'due south invention of the printing
press, most 1450-55, were images
available to a broader, though still
express, audience for use in their
own homes. Until and so worshippers
were dependent upon the creative
techniques and adroitness of
stained glass artists.
Origins of the Glazier's Art Traditionally, stained drinking glass was used in Christian art as an architectural medium and, equally such, it was integral to the fabric of a building; non only, or always, a work of art, but also a screen letting in and modifying the low-cal and keeping out the elements. Its development every bit a major art form in the Middle Ages was dependent on the needs of a powerful client, the Christian Church, and the development of compages (notably Gothic architecture) that allowed for ever larger openings in the walls of both humble churches and nifty cathedrals, producing monumental walls of coloured lite.
The exact origins of stained glass fine art are uncertain. Sheets of glass, both blown and cast, had been used architecturally since Roman times. Writers as early on as the fifth-century mention coloured drinking glass in windows. Aboriginal glass was set in patterns into wooden frames or moulded and carved stucco or plaster, simply each network had to be self-supporting, which limited the kinds of shapes that could be used. When or where strips of lead were starting time employed to hold glass pieces together is not recorded, just pb'southward malleability and forcefulness greatly increased the multifariousness of shapes available to artists, giving them greater artistic freedom. Excavations at Jarrow, in northern England, take yielded strips of pb and unpainted glass cut to specific shapes, dating from the seventh to the ninth centuries. The procedure of making stained glass has inverse very piddling over the centuries. Nosotros can still look to a treatise written late in the 12th-century by a monk using the pseudonym Theophilus for a basic agreement of the steps required both to make sheets of transparent coloured glass and to fabricate a window. Over the centuries, innovations have refined techniques and expanded sure ideas, yet the basic concepts outlined past Theophilus have not changed. In his time, the understanding of glass chemistry was limited to anecdotal observation, producing a circumscribed body of knowledge of what did and did not work. Mod stained-drinking glass artists and artisans have at their disposal centuries of further research and therefore a more complete scientific understanding of their materials.
Stained glass is usually designed for a particular setting, with a specific light and an expected audience. Both setting and audience can change radically over time. New buildings may block the original lite; corrosion and clay may obscure the details; vandalism and poor maintenance may cause loss of glass. In addition, stained drinking glass has always been an expensive medium: the materials are costly and the fabrication of a window is time-intensive. It is the intrinsic beauty of the materials and the exceptional skill of its practitioners that have ensured its secure place in the history of fine art.
Glassmaking Materials The three basic glassmaking ingredients are silica, an alkali and an alkaline world. Silica, usually in the form of sand, forms the vitreous network of drinking glass. By itself, silica requires a very high heat to melt, so a 'network modifier' is introduced in the form of an brine to break up the strong silica bonds, assuasive the glassmaking to be washed at a lower temperature and making the drinking glass 'metal' more than workable. A 'network stabilizer', usually in the class of lime, an element of group i earth, is added to rebuild the network, producing a stable glass. Various metallic oxides may be used to colour the glass batch. The ii alkalis more often than not used for sheet glass are soda and potash. We know today that soda forms a much more stable glass, just potash was used extensively in the Middle Ages and is the method described past Theophilus. The materials used in the making of potash glass were readily available to medieval glassmakers, who located their workshops in woodlands to satisfy their requirements for sand and for fuel to fire their furnaces. They found that they could produce a usable range of colour pigments with just sand and the potash obtained from the ashes of beech copse, which already contained the balance of metal oxides, such every bit iron and manganese, necessary as colourants. Even so, proportions differed somewhat from batch to batch, as the soil and other conditions changed from tree to tree. A skilled glassblower could observe what colour glass the materials yielded as sheets were being blown and then manipulate the oxidation and reduction conditions in the furnace to obtain other colours from the batch. Specific colourants were also added, such as cobalt for blue, and copper for red. Sometimes the colourants were already in glass form and might comprise soda as the alkali or lead oxide, which performs both network-modifYing and network-building functions in the glass matrix. In an early example of recycling, ancient vessels and opaque drinking glass tesserae used in mosaics were added to the cook to colour the glass batch. The composition of specific medieval glasses tin can be very circuitous due to impurities in the raw materials, the colourants used and other additives, all of which bear upon the drinking glass's working and ageing characteristics. These vitreous colours are permanent, only their exposure to the sun can crusade manganese, a mutual ingredient in glass batches, to shift, resulting in a slight change of color. The purple tint created by the shift is noticeable by its absence at the glass edges that had been covered by the lead cames, and helps to account for some of the bug that 19th-century glassmakers encountered when recreating medieval spectacles from compositional analysis.
Although Theophilus discussed both the manufacture of sheet glass and its use in the making of windows, stained-glass artists rarely fabricated their ain glass. While obviously connected, these are two very dissimilar and highly specialized disciplines. Some stained-glass workshops did have glassmaking facilities on site, simply glassmakers were commonly located most the raw materials they needed for their work. Many medieval accounts item the cost of transporting finished sheets of drinking glass to workshops. Modern workshops have the same separation. Transparent drinking glass that is coloured throughout, while still molten in the 'pot' of the furnace, is known as pot-metallic glass. However, not all glass is coloured throughout. Reddish, oftentimes called carmine, tin can be hard to brand. The colourants used to create it must be present in such intense concentrations that the glass appears black once it attains the thickness necessary for architectural glass, usually about three mm (1/eight in). Additionally, red glass must usually be reheated in lodge for the color to appear. In the twelfth and thirteenth centuries streaky reds were used, which had interspersed lines of red and clear. Past the 14th-century this method had been abandoned in favor of flashed glass, using a technique employed much earlier for vessels, called 'casing'. A molten gather (a glob of glass adhering to a blowpipe) of i colour is coated with a thicker gather of a different colour, usually clear, or a tint of green, yellow or some other colour. This layered gather is then blown into a sheet. Subsequently cooling, areas of the thin flash can be removed by abrasion, revealing the colour of the base glass. One could then have ii colours side by side on one piece of drinking glass without needing a atomic number 82 line, and so more intricate designs could be executed with fewer leads. Afterward, hydrofluoric acid was used to dissolve the flash in a chemical reaction and abrasion was abandoned. Abrasion removes all of the flash, simply with acrid etching it is possible to take gradations of removal, allowing shadings and various densities of colour. Nonetheless, it is highly dangerous to the user and must be handled with great care.
Forming and Shaping of Stained Drinking glass
Glass can be made into sheets in several ways. Early sheets were bandage onto a flat surface, such as sand or wet wood. With the invention of the blowpipe, in the first century BCE, drinking glass could be formed much more quickly. Two methods take been used for blowing sheets: the cylinder/muff and the crown method. In the beginning, a bladderlike shape is blown. Offset one end is opened upwardly and then the other finish is removed, forming a cylinder (or muff). This is then split down one side and flattened into a canvass in a re-heating procedure. In the crown method, a bubble is diddled, transferred to a metal rod called a punty (or pontil), pierced, and spun out, yielding a round sheet with no need for flattening, but with a pontil mark remaining in the centre. A 3rd, less commonly used technique chosen 'Norman slab' was developed in the 19th-century and involves blowing the bubble into a mould to grade a hollow cake that is later separated into small-scale sheets. Modern paw diddled drinking glass is referred to as mouth-diddled or antique glass. All glass must undergo a controlled cooling period, known as annealing. The drinking glass is placed in a special annealing oven, called a lehr, and the temperature is gradually reduced. If cooled likewise quickly, the molecules cannot movement into a stable configuration. If cooled too slowly, the glass tin can offset to form crystals and devitrify. Desperately annealed glass has interior stresses, which make it hard to cut and tin cause it to jump apart as it is scored. Opalescent glass is a rolled translucent to semi-translucent milky drinking glass. Information technology is often streaky, with a mixture of different colours. Glass objects were made for centuries using milk-white glass, but it was not made into flat sheets for stained glass until the mid-1870s, when artists John La Farge and Louis Condolement Tiffany began exploring its possibilities. Its development gave birth to the American Opalescent Style.
For rolled sheets of glass, the molten glass passes betwixt rollers set about three mm autonomously, thereby determining the thickness of the drinking glass. Textures can be imprinted on one of the rollers and pressed into the molten drinking glass as it passes through. Tugging or pulling the glass also affects the surface, producing a rippling upshot. Machines began to be used in the 19th-century to make both auto-blown and rolled drinking glass in a variety of textures and colours. In some factories the glass is a continuous ribbon from the batch melting in the furnace through the rollers and then onto a long annealing lehr. At the cease of the lehr, sufficiently cooled, it is finally cut into sheets.
For unusual or unique effects, mitt-rolled sheets are sometimes preferred. For this, a ladle of one or more colours is poured onto a steel table, mixed to a desired integration and pushed nether rollers. For pall drinking glass, the puddle of glass is beginning rolled and then manipulated to produce iii-dimensional folds. It is finished through a roller, but, after manipulation to produce folds, is left in three-dimensional relief. This must be washed speedily, while the glass is still malleable. Over the centuries, technological advances allowed hotter glass furnaces and greater control over raw materials, yielding more homogeneous, thinner glass, with fewer bubbles and impurities. This drinking glass lacked the richness that before drinking glass had possessed - partly every bit a result of its 'imperfections' - and the rebirth of stained drinking glass in the 19th-century led directly to a similar rebirth of the art of medieval glassmaking. No affair how useful car-made glass may be, nothing can rival the inherent beauty and versatility of mouth-blown antique glass.
Stained Glass Artist's Designs: Sketches and Cartoons The procedure of making a stained drinking glass window begins with the artist's sketch, known in medieval times as the 'vidimus' (Latin for 'we have seen'). This can come from either the studio or the client and represents an agreement of how the final window will look. The sketch is drawn to scale and from information technology a full-size rendering, or cartoon, is fabricated, which may exist done by hand or, as is often the practice today, blown up mechanically. Some design adjustments are often necessary with the change in scale. A drawing can be very detailed, with painting worked out and the basic colour selection indicated.
Before paper was readily bachelor, the full-size drawing was fabricated on a whitewashed tabular array that was used for cutting and painting the glass, besides as for putting the finished window together. Remarkably, i such medieval table has survived, if but because information technology was afterwards used to make the door of a cabinet. Two fourteenth-century windows fabricated on it also survive in Gerona Cathedral in Spain. Examination under ultraviolet light has revealed several layers of drawings on the lath, which contain atomic number 82 lines, symbols indicating colours and some of the nighttime trace lines that were to be painted on the glass. In that location are too nail holes from the glazing, or leading-upwardly, of the panels. Sketchbooks and copybooks were often passed downward from glazier to glazier. With the increasing use of paper in the 15th-century, full-size cartoons could be saved, handed down and reused. Artists who worked in a variety of media could also make them exterior the glazier's shop. Albrecht Durer and Hans Holbein the Younger drew many designs for stained-drinking glass panels, which others then interpreted. Stained drinking glass is often a collaborative fine art and the conscientious pick of collaborators has always been crucial for the success of the terminal artwork. Run into also: Metalwork.
Glass Cutting: Scoring/Grozing After the layout and patterns are made the glass is cut. The craft part of the medium demands that the various steps be performed with cracking accuracy so that the upshot volition exist a strong and stable window. For example, if the drinking glass pieces are cut too large or likewise small, the window will logically exist too large or small, a wholly unacceptable result. Usually but 6-12 mm of the console border sits in the frame, and then pocket-size discrepancies accept real consequences. At the very least, bad cut means that adjustments will be necessary during leading and that associates will be difficult.
In the Eye Ages sheets of glass were first split into smaller pieces using a hot iron. Heat, aided past water or spit, was used to initiate a break and the sheet was split in two. This rough shape was then refined using a grozing iron, which was a metal slot or claw into which the edge of the glass was slipped. By pulling the iron downwardly and away, the glass edge was nibbled into shape. Skilled craftsmen could make difficult and intricate shapes.
At some point in the history of the craft, an observant artisan realized that a deep scratch or score made on the glass surface would give better control of the breaking. One can sometimes meet these scratches coming off grozed edges on medieval pieces and even notice, on occasion, ungrozed edges from the period. Diamonds set in handles are known to have been used for scoring past the 14th-century and were probably used earlier, although edges were normally withal grozed, and diamonds are still used to score drinking glass today, mainly in Europe. The steel wheel cutter was developed in the 1860s. As the wheel is rolled beyond the drinking glass it focuses a tremendous corporeality of pressure just at the bespeak where the wheel meets the glass, creating a surface fissure. The scored glass is and then snapped apart, using the hands or a pair of pliers as a fulcrum.
Early on scores were somewhat haphazard. To be a success, a score must travel from one border of the glass to the other in an unbroken line. If the bike has a nick in information technology, there will exist skips in the score and the break will go awry at the skip. Glass is an amorphous material; it has no grain to guide a break. The score is the starting indicate, but the artisan must decide where else to place scores in order to suspension abroad extraneous drinking glass without putting too much stress on the pieces that are to be kept, for the drinking glass volition suspension at the bespeak of least resistance. Some shapes, such as inside curves, are difficult to cut and require some skill to make. Different types of glass cutting differently. Even with relatively uncomplicated shapes, one ever needs extra glass that will end up as cutting-off, even more so when shapes are difficult. The lead lines are painted onto a large piece of plate glass for the colour pick. Every bit each piece of glass for the console is selected and cutting, information technology is attached to the plate glass with small-scale globules of wax (a process called waxing-upward), allowing the creative person to study colour relationships in the light and make changes as needed. This stride is critical, since colour relationships change depending on the size of the pieces and the colours that environment them. Colour relationships too modify depending on the light in which they are viewed. Daylight differs significantly from fluorescent or incandescent light and when selecting glass one must mimic the eventual lite source. The cut segments of glass stay on the plate for painting.
For other styles of Medieval fine art, please run across: Romanesque Art (c.1000-1200), Gothic Art (c.1150-1375) and International Gothic (1375-1450). For ane of the greatest examples of Gothic style stained glass that fills most an unabridged wall, see the incredible Sainte Chapelle (1241-48) in Paris. For more, come across also: English Gothic compages c.1180-1520.)
Drinking glass Painting
The German term "Glasmalerei" , or drinking glass painting, nigh aptly captures what enabled stained glass to motion across its obvious decorative and practical functions to develop into a powerfully expressive medium. Painting on glass gave artists the opportunity to construct big-scale imagery using light, color and line. With stained glass, dissimilar other graphic media, the artist must be sensitive to translucency as well as line and grade. The modulation of light animates the image.
Pigment is used both to control lite and to provide details. It tin can exist applied in washes, mats and dark trace lines to both the front end and the back of the
glass. The trace lines provide the main outlines. Crosshatching, using thick or thin trace lines, and mats provide the shading. The same paint mixture can be used for both, diluted in different amounts or mixed with different media. Glass-painting styles have changed over the years, peculiarly in the application of mats, which have ranged from a thin wash with visible brush strokes, to a smoothed or 'badgered' (referring to the beard used to smoothen the pigment) mat. The annoy tin can also be used to apply texture to the wet or dry out mat through a striking activeness, called stippling.
The vitreous pigment for stained glass is composed of a low-firing, essentially clear drinking glass-flux and opaque metallic oxides, generally iron or copper. It comes in powdered course, assuasive the artist to mix it with water, vinegar or oil and layer it, depending on the desired consequence. A binder, such as gum Standard arabic with h2o or Venetian turpentine with oil, is used to temporarily hold the paint to the glass. The paint must exist congenital upward in a series of sparse coats, either using different binders or firing between applications. A variety of brushes, sticks and other tools are used to employ and remove the paint before it adheres A highly important innovation appeared in architectural drinking glass around the beginning of the 14th-century: silver stain, the only truthful 'stain' in stained glass. Since the 8th century, Islamic drinking glass vessels, prized imported luxuries during the Middle Ages, had used silver stain as a colourant in painting designs on predominantly clear glass. With increased contact with Islamic art in Spain every bit the Christian kings of Aragon and Castile conquered Muslim territories, the innovation was eventually adopted by French artisans. In colouring the glass, a silver oxide in an opaque medium is practical, usually to the back of the glass, and fired. During the firing, silver ions migrate into the drinking glass. They are suspended within the drinking glass network, rather than fused onto the surface, every bit drinking glass paints and enamels are. After firing, the opaque medium is removed from the glass, revealing the transparent yellow. Glass can be stained a pale yellow to a deep carmine, depending on the limerick of the drinking glass and stain, the number of applications, and the temperature of the kiln, and the stain can read as green when fired onto blue glass. Argent stain thus enables the painter to add various shades of yellow to a slice of glass without using a separating lead. It also helped to solve the centuries-onetime problem of producing a readily available and reliable yellow glass. Due both to a dwindling source of pot-metal glass sheets and to changes in calibration and sense of taste, by the mid-17th-century many drinking glass painters were increasingly turning to coloured glass enamels instead of pot-metal glasses. Enamels are intensely coloured ground-up glasses that are painted onto the base of operations glass, which is frequently a light tint for best consequence. They fire at lower temperatures than opaque vitreous paints. Enamels are fused onto the glass surface, and, while they are not opaque, they lack the transparency of pot-metal sheet drinking glass. The revival of stained glass in the 19th-century was very much a reaction against the extensive utilise of these paints, merely they remain useful and are notwithstanding employed today. The mankind painting (heads, hands and feet) found in Tiffany windows was usually washed in coloured enamels. As a dominion, enamels are not as durable as vitreous paints, although vitreous paints can also fail, due to poor composition of the paint or the base of operations drinking glass, or to under-firing, as well equally to environmental factors.
permanently. The glass is fired in a kiln to approximately 6760 C (1,250° F), at which bespeak the drinking glass-flux fuses to the base of operations glass, which is commencement to soften, belongings the opaque metallic oxides in identify.
The Use of Lead Cames The advantages of pb in window glazing are several and significant: it is malleable; information technology can be formed to nearly whatsoever shape; it solders well and hands; it tin survive for centuries with niggling or no maintenance. The earliest lead cames were cast. Molten pb was poured into a heated mould and planed to shape after cooling. By the end of the 16th-century, almost all lead came was milled, which took less fourth dimension than casting but yielded a thinner, less substantial came. Lead today is made in a multifariousness of sizes and shapes: circular, flat, high or depression heart, wide, narrow and so on.
The alloy used is important. Pure pb, while technically possible today, is not a good choice, since it is more susceptible to fatiguing and attack by acids than an blend containing trace amounts of antimony, tin can and silverish or copper. Onetime leads and cut-offs from new cames are recycled. Cames may also exist made from other metals, such as brass and zinc, although their lack of malleability makes them much less useful. When the glass is ready to be leaded together, or 'glazed', the glazing guide is placed apartment on the demote and strips of wood are nailed down to concur the assembled pieces. The outer piece of lead is cut and placed on the guide, and glass is slipped into place. The next strip is cut and placed, and the next piece of glass inserted, and and then on. During the process the glass and pb are held in place using glazing nails. Nailing can cause chipping of the drinking glass edges, so they are protected using modest pieces of lead. The guide ensures that the panel's size remains right and abiding. Once all the glass and leads are in place the panel is set to be soldered at the joints, both front and back. The space betwixt the glass and leads must exist filled in society to requite the console additional forcefulness and to make it waterproof. Linseed oil putty is either brushed or thumbed under the leads on both the back and the front end of the panel. Finally, backlog putty and oils are cleaned off he glass and leads.
Barring
In an architectural setting, windows are subjected to extremes of weather - to wind pushing in and pulling out, to rain, sleet, hail, snow and then forth. The malleability that makes lead platonic for the freedom the artist needs as well makes windows vulnerable to gravity and wind, and then back up confined must be anchored into the frame and attached to the stained glass. Panels are oft prepare individually on T-confined set into the frame in guild to support the weight of glass and lead.
Conservation, Preservation, Cleaning and Repair of Stained Drinking glass Stained glass has been repaired and restored since its primeval days. Complete windows survive that date back at least 900 years, and some individual panes are even older still, but this cannot alter the fact that glass is a highly vulnerable medium. Drinking glass loss occurs due to random vandalism, weather condition, political and/or religious upheavals (organized or otherwise) and elementary changes in taste. Their function equally an essential part of a building's fabric has helped save many windows, since window openings have to be filled with something and stained glass is an expensive fabric that is usually replaced only with great difficulty. However, in that location are many accounts of windows being removed and sometimes destroyed because of what was seen as offensive subject affair or to make way for new windows more in tune with current fashion. This is how many works of stained glass art have come into museums and individual collections.
Glass is it self vulnerable to disuse. Seemingly innocuous water is the first to attack. Its presence, in liquid or vapour form, promotes the leaching of the alkalis from the glass, weakening the network and building up corrosion products on the drinking glass surface, although rainwater can actually be beneficial to a window, every bit it tin wash away leached alkalis earlier they go concentrated on the glass surface. The style each drinking glass ages depends on its
composition and its surroundings. Certain spectacles can develop an opaque surface crust that retains wet and becomes highly alkali metal. As the leaching solution becomes more alkaline (above pH 9), the silica network itself is attacked. Air pollution is thought to exacerbate the procedure. However, not all corrosion is due to weathering. It was observed that windows removed for storage and kept in clammy conditions, notably during World State of war II, showed marked deterioration, while those kept in dry conditions fared much improve. At the time, it was not realized that damp conditions would negatively affect the glass and paint.
Protective glazing, an external layer on the exterior of a window, is now a conservation possibility and, in Europe, has been one of the almost effective ways to protect medieval drinking glass. Such handling is valid merely if the space between the stained-glass window and its protective glazing is vented to allow a moving cavalcade of air. Otherwise, the window traps wet, which actually accelerates deterioration of the historic drinking glass. Nineteenth- and twentieth-century glass is less vulnerable than medieval drinking glass, owing to its unlike composition, and rarely needs such protection. In modern buildings with climate control, an architectural choice may be to station the creative glass on the interior, almost as a screen in front of the functioning window. This solution has also been used for conservation of celebrated windows, thus removing them from the stress of functioning as a weight-bearing element.
Just as glass pigment is a film on the surface of the drinking glass. then besides are dirt and corrosion, which obscure the painted details and cutting downwards significantly on the calorie-free passing through the drinking glass. Since stained drinking glass relies on transmitted light, these strange materials must ofttimes be removed and so that light may smoothen through. However, such cleaning is non ever easy, nor is information technology elementary to do nether even the best of circumstances. Information technology must be approached with great care. Glass paint can exist fragile and hard to distinguish from the motion-picture show of clay. Opalescent windows are often several layers thick. Soot, dirt and old putty trapped betwixt the layers can be very hard to attain and they considerably diminish a window's effect.
Traditionally, there were only 2 reliable waterproof methods of repairing breaks or losses in architectural glass: the replacement of the broken glass with a new piece - sometimes a good match, sometimes not - or the insertion of repair leads. The former means that original material is completely removed. The latter is unsightly, compromises the panel's legibility and normally results in partial removal of original cloth, as the intermission line is grozed to make room for the center of the repair lead. Today, broken glass can be repaired using a variety of methods, depending on the setting. In a museum, exposure to weathering, ultraviolet light, humidity, temperature fluctuations and the like is stringently controlled. The same is not true in an architectural setting, where the term 'museum conditions' is often used to announce the presence of some form of protective glazing, although actual weather condition vary widely. The protection is non just for the stained glass, simply as well for the textile used to repair it. Traditional materials have been used in the field for a number of years, being both well known and well understood. Accelerated ageing tests must exist performed on newer materials to give an indication of how they volition react over time - although, in the end, only fourth dimension itself will actually tell. Epoxies have proved very effective for bonding cleaved glass. They attach well to glass and their refractive alphabetize, which is the amount by which a ray of light is aptitude when travelling from air into a solid, can be close to that of the various glasses, then they significantly reduce the reflection of light off a break edge as they hold the glass together. However, they exercise not agree up well against the weather, so their use in architectural settings is limited to areas where they can exist protected, either with overall protective glazing or with a plate of glass placed directly behind the glued repair. RTV silicones and neutral cure silicones are useful where the repair will be exposed to the elements, since they have tested amend than epoxies under such conditions. Their biggest drawback is that their refractive index is not a proficient match for much glass, and so light reflects noticeably off the cracks. With opalescent drinking glass this is not a problem considering it is then dense, but with transparent glass it can be unsightly. Silicones have some 'give', which is good for simple breaks when the glass is under wind load, but they are not a good pick for a compound break, since they may allow too much move.
Copper foil is another culling, although it reads as an opaque black line, admitting a narrow one. It consists of a thin copper strip with adhesive on one side, which is wrapped effectually and pressed onto the edge of the glass. The pieces are then soldered together, and so the drinking glass being repaired must be able to withstand heat. It has the reward of being a mechanical, reversible repair. Lead came should never be used to repair new breaks in glass. The heart of the pb joining the upper and lower flanges pushes the pieces of glass autonomously, and so they must invariably be grozed in gild to realign the painting; in addition, the upper and lower pb flanges cover painted details, bringing them into contact with the waterproofing putty and moisture. Even flanges used to hide a break on the front and back without actually inserting a lead can touch on the paint and the readability of the graphic. With old breaks mended with pb came, the restorer and client ordinarily talk over the advisability of removing the sometime came and replacing it with copper foil or edge bonding in order to restore greater legibility.
Deterioration of Lead Cames
Lead cames perform the very important role of supporting the glass, but in addition to that they provide a rhythm and scale to the composition. Deciding where the lead lines should be placed is an of import stride in the realization of any sketch. When releading, it is important to institute the location of the original lead lines so that the conservator or artisan does not end up reinterpreting the limerick according to his or her own preferences, since the choices were fabricated past the piece of work'southward original creators. Put another way, who are nosotros to argue with the choices made by the work'southward original creators? Over time, the bicycle of expansion and contraction due to heating and cooling can cause cracking and metal fatigue, particularly in milled and extruded leads. While the atomic number 82 itself is an artifact, when it has lost the power to hold the glass securely, ane must consider replacing it. Early on cast leads are occasionally found on panels from the 16th-century and earlier. Every attempt must be fabricated to go on these rare leads. Later milled leads have milling marks on the hearts. Usually these are a series of slanted and perpendicular lines, but occasionally one finds names, dates or symbols. These should be recorded, since they can tell usa something about the history of the slice.
There is no accented dated fourth dimension failure for leads. Decisions about releading need to exist made case past case. If releading is warranted, information technology is of import to duplicate the original leads in width and height. It is not uncommon to find medieval pieces releaded in the nineteenth century with wide flat leads, which cover of import painted details. Leading is non just a mechanical operation; it requires skill and attention. A plodding or sloppy releading destroys the energy of the original line. The modernistic globe has brought many new ways of working with glass. Dalle-de-verre, a technique that embeds chunks of glass in concrete or epoxy, was popular in the 1950s. In the last twenty years, new techniques, such every bit fused, acid-etched, moulded or photograph-screened treatments have been used in many mod glass installations. Inexpensive commercial glass is now oftentimes combined with other glass and glazing processes, especially large-scale installations. Stained drinking glass however, however largely follows the general guidelines set downwards past Theophilus, testimony to the ability of the material and the lasting relevance of historic windows for inspiration in the present. Although we may solve bug in new means or make utilize of new technologies, the creative person is still using glass to transform the lite of interior space.
References: nosotros gratefully acknowledge the utilize of materials from The History of Stained Drinking glass (Thames & Hudson, 2003) written past Virginia Chieffo Raguin. This magnificent work contains a wealth of wonderful pictures of stained drinking glass windows together with a masterly explanation of the evolution of stained glass fine art: essential reading for any students of medieval compages and Christian art.
Source: http://www.visual-arts-cork.com/stained-glass-materials-methods.htm