Stained glass

The stained glass is a formed decorative composition of parts of Verre coloré.
Since the beginning of the the Middle Ages, these parts are assembled by rods of Plomb. This process, although today always dominating, is not the only of use: other techniques, such as those of the copper ribbon (also called Tiffany method, of its originator Louis Comfort Tiffany), of the flagstone of glass enchased in the concrete or silicone, of joinings (with resins or polymers, and stained glass with free glass, can be used or combined.

A stained glass is called Vitrerie when its drawing is Géométrique and repetitive (for example of the rhombuses or the terminals). Glaziery is generally clear and without painting.

A stained glass and a glaziery are carried out according to the same process by associating lead and glass. Glass used is plane, a thickness varying between 1,5 mm and 5 mm, and lead is presented in the form of rods in the shape of H lying. The parts of glass are crimped in leads then the unit is maintained definitively thanks to the welding S carried out with each intersection of leads.

History

Origins

Coloured glass was produced since the most moved back times. Such an amount of the Egyptians whom the Romans excelled in the manufacture of small objects of coloured glass. The British Museum has two exceptional Roman parts, the cup of Lycurgue, whose color color mustard takes reflections crimsons when the light the cross-piece and the Vase Portland cement, blue harms white incised decoration.

In the first Christian churches of IVe and Ve centuries, one can still observe many openings occulted by reasons in very fine alabaster sheets crimped within frameworks out of wooden, giving an effect of primitive stained glass. Similar effects were reached with a greater sophistication by Moslem creators in minor Asia by using glass coloured instead of the stone.

The medieval stained glass

As an artistic form, the technique of the stained glass reaches its plenitude with the Middle Ages. During the periods Romance and primitive Gothic (950 to 1240), the openings developed requiring moreover glazed large surfaces. The stability was ensured by robust iron executives. These models are still visible in the Cathédrale of Chartres and at the Eastern end of the nave of the Cathédrale of Canterbury.
With the decorative development of the Gothic architecture, the openings became increasingly large, improving lighting of the interiors. The Gothic architecture innovated by introducing a bulk-heading of the windows by vertical pillars and reasons for stone. The complexity of these openings reached its apogee in immense bays of the blazing style européen.
Integrated into the tendency to the vertical rise in the cathedrals and the parish churches, the stained glasses became increasingly daring creations. The circular form, or Rosette developed in France, evolved/moved starting from relatively simple borings in the stone walls to the immense rosettes, like that of the western pediment of the Cathédrale of Chartres. These models reached an enormous complexity, the stone lace being ramified in hundreds of various points, as in the the Ste Chapelle with Paris.

The stained glass in flagstone of glass

It is about a particular technique, very recent compared to the secular Art of the traditional stained glass, since invented by monks Trappists in the Fifties. Initially, work is carried out using a corner and of a hammer, which serve to cut pieces of glass in small glass blocks as 2 to 3 centimetres thickness having the shape of a brick. HTTP: /www.vitrail-architecture.com/boutique/images_produits/fchoix-dalle_1.jpg: One poses the part of glass on the corner, and strikes using the hammer to separate from the pieces until obtaining of the form desired, according to the same process of " calibrage" described above. The parts thus obtained are then laid out according to the model in a formwork, formed by wood cleats. This formwork is used to run the concrete which constitutes the reinforcement of the flagstone of glass, in desired dimensions and forms One runs then the concrete During the operation of casting, metal stems are plunged in the concrete to reinforce the reinforcement.

It is the need for having a very robust reinforcement, because of the weight of the parts of glass, which gives to these stained glasses this massive aspect when they are seen outside of a building.

Nowadays, the technique evolved to the use of resin " epoxy " , whose solidity made it possible to reduce the widths of reinforcement, passing from minima of 4 centimetres to less than 1, following the surface of the stained glass.

The stained glass with free glass

It is about a technique of contemporary stained glass made up of parts of glass of various natures and textures (glass ancient, chips of flagstone of glass, stems of glass, balls of glass, glass of beach, glass of recovery, etc) deposited and combined between two panes, spaced approximately 2cm, crimped within a metal or wood framework. This technique was developed with the beginning of the year 1980 per Guy Simard, artist glass in Quebec. Though proceeding of the same spirit, it differs passably from the technique of free rolling patented by Eric Wesselow (Price of Rome), Canadian glass artist of Polish origin.

The stained glass with free glass is different from the traditional stained glass crimped with lead under five aspects:

1. Whereas the large stained glasses of churches or cathedrals are presented in the form of large flat tints, the stained glass with free glass rather shows a very large variety of textures. The stained glass then is said or perceived as being more dynamic, in the sense that when the specific light (a point of light), the sun for example, continues its race, or that the spectator moves compared to the stained glass, the light effects also move, passing from a part of glass to the other.

2. The construction of a stained glass with free glass requires approximately four to five times more time than a traditional stained glass and the quantity of glass used is multiplied in the same proportion. With the result that the stained glasses with free glass are approximately as heavy as the stained glasses in flagstones of glass.

3. A stained glass with free glass is built a little with the manner of a smooth high tapestry. It is assembled upwards. The parts of glass being deposited freely in the glazed box which is used to them as cockpit, it is followed from there that it is absolutely impossible to produce two absolutely identical stained glasses with glass free, which is possible, on the other hand, in traditional stained glass.

4. A stained glass with free glass does not contain any adhesive nor does not use any form of setting. What retains glass, it is only its framework, its container of pane and metal or wood. This means that the parts of glass inside the stained glass with free glass can move if, for example, the stained glass is turned of 180° to the vertical, i.e. when the top becomes bottom and that bottom is found in top. Thus, more glass is compact, less it can move.

5. A traditional stained glass with lead could, in extreme cases, to measure two meters out of two. A stained glass with free glass of more than one square meter implies particular technical constraints. In particular, the side pressure increases quickly in the center of the stained glass, with the result that the panes which retain the parts of glass tend to bulge. The larger the framework is, the more the panes must be thick. For example, to the panes of 4mm thickness for a framework to 60 X 60 cm are enough, whereas it is necessary to use pane from 5 to 6 mm for a framework of one square meter.

Symbolic system of the stained glass

The stained glass is regarded as the symbol of the Immaculate Conception, the light crossing the stained glass to generate the image, in comparison with the divine light which crossed the virgin to give birth to Christ.

Principal stages of construction of a stained glass to lead

Design

Contrary to other techniques like the oil-base paint, the technique of the stained glass leaves little place to the Improvisation during the réalisation.
The drawing, the color, the solidity and the perenniality of the stained glass… but especially the quality of the light which will penetrate in architecture must be upstream defined.

The model

It is a document which shows a detailed outline of a stained glass by representing it on the scale 1/10.
The model comprises the layout of leads, the coloring of glasses, possible painting and the passage of the metal reinforcements. It is used as starting point for the development of an estimate. The model emphasizes the proportions of the parts the ones compared to the others and the size of the window (especially in the case of glazieries).
The model is used as reference document throughout the realization of the stained glass.

Coloring

This stage determines the harmony of various coloured glasses. One chooses glasses according to the colors indicated on the model and by taking account of their nature: antique, plate, printed… The samples of glasses are compared on a canopy of exposure to observe the report/ratio of the colors between them.

The layout

It is the “technical design” of the panel, carried out on scale 1/1 on paper bubble. The network of leads is traced with precision by using the model like model. It is then gauged so that glasses are cut. In the case of a figurative stained glass: one proceeds to an enlarging of the model. If a paperboard is had, one can transfer the drawing of leads on paper. In the case of a glaziery: one uses a drop pen to defer the identical spacings.

The parts are differentiated by numbers in order to be easily localized. These indications can be the number of bay, the number of the panel in bay and the number of the part in the panel. They can also mention the reference of glass which is allotted to them. A glass leaf can have variations of value which will be visible on the parts. One can thus indicate the direction of the range (+) or the selected intensity (strong, average, weak).

The copy

Before being gauged, the layout is deferred on a copy. This “safeguard” is important for the realization of future copies or possible repairs of broken parts. It is also used for positioning the parts which are cut and avoiding confusions and the losses. A second copy can be carried out for the setting which will be used as guide while being slipped under the panel.

Calibration

After having carried out the copy, the layout is cut out methodically. Calibration is used to preserve measurements of the panel by taking account of the assembly glass/lead. It is advisable to remove the web thickness of lead (1,75mm) on the layout. This one is distributed on each side of the feature, then removed. Strong paper gauges are obtained which are used as guide for the cut of each part. It is carried out differently according to the reason for the panel: Calibration with the blade and the reglet is used for the rectilinear reasons (rhombuses, terminals,…) whose cut of the parts is often done with the measuring rod. The tool passes symmetrically on each side of the feature. Calibration with the scissors to be gauged is used to cut out the curved forms. They have a central blade measuring 1,75 mm which withdraws the web thickness of lead.

Cut

The cut of the parts is very precise because each defect can modify the result, either in measurements, or in the reason. The gauges are used as guide for each part and their superposition with the parts must be perfect. One uses a diamond (natural or synthetic) or a glass-cutter (caster of glazier). Generally, the action of the cut is done in two times: a stripe then an unhooking. If the stripe is correctly carried out, glass “slips by” and unhooking is done rigorously at this place (the molecules are separate to allow separation then). In all the cases, plus unhooking is late, less it is easy because the cut is closed again then little by little. If the hand cannot take down the two pieces, one uses a grip to be detached positioned perpendicular to the feature of cut. If the edges are imperfect after unhooking, one rectifies them with a grip to be notched. For a better completion, the stone carborundum makes it possible to improve the edge of the parts.

The organization is different according to the reason and the type of parts to be output:

If each part is single , one uses each gauge individually. This case often applies to reasons gauged with the scissors with three blades. The glass-cutter rigorously follows the edge of the gauge without the empiéter.

to obtain a part, it is necessary to carry out several features of cut, i.e. as many features as its contour includes/understands some. Generally, the most difficult sides are cut in priority to avoid waste of time and of matter.

For the parts which have hollows, one proceeds in “cuts of call” which make it possible to progress successively towards the desired form.

For a part which is repeated in series , the successive passages of the glass-cutter will deform the gauge. One can manufacture of it a copy in a material more resistant than one calls foil .

If the parts have identical and parallel widths, they are cut in series using a measuring rod. The bands are output while making slip the measuring rod on the glass leaf against the rule of the table of cut. To cut rectangles, one needs a measuring rod for the length and a second for the width. The first band is output by the second measuring rod. To cut squares or rhombuses, the same measuring rod twice is used! This process makes it possible to precisely preserve dimensions of the parts which must be identiques.

to remove in series the same part of a part on rectilinear board, one manufactures machines . The part is fixed in an assembly of small rules out of wood where one makes slip the glass-cutter against the last nailed piece. In this way, the passage of the tool is done systematically at the same place.

Setting

Also called “ put out of lead ”, it starts when the parts of the panel are cut and that they do not require any more any treatment of decoration (painting, cooking, sanding,…). Setting gathers the whole of the gestures to assemble glasses and leads. The “lead way” determines its organization. It is studied as a preliminary to obtain a solid and logical network during the assembly. Beyond its mechanical function, the lead way draws the reason for the stained glass; setting must thus respect the drawing so that it is readable.

The equipment and tools: The editing table is the support which will receive the assembly. It is out of wood (of poplar preferably) and receives two rules nailed perpendicularly on its edges. These rules are bevelled to receive the lead of entourage. The assembly comes to rest in the corner formed on the left or on the right of the following assembler if it is left-handed or droitier.

The assembler uses knives of assembly of various widths which are used to cut lead and to handle it. One can also use a knife with lead in the shape of bill hook. This one has of a curved blade finishing at a peak and a handle often provided with a tin thrust to replace the hammer. The hammer is used to type the ends of leads, to plant the nails of assembly, to pack glasses in leads (with its handle) and to pack the panel when setting is finished. Open-lead is used to draw aside the wings of leads so that they accommodate the parts. The nails of assembly are used to temporarily maintain the parts during the assembly. Their form is conical not to scale glass and so that they are removed easily.

Principles of setting out of lead:

Each lead must be slightly flattened at its end in order to be able to penetrate to the heart of another already installed. A lead located between two glasses must be immediately crossed and flattened so that the following can cover the assembly carried out. A lead is never cut in the middle of a part, the following always comes to stop it. Before being welded, the wings of leads are folded back using a spatula to fold back to consolidate the panel. This tool is out of wood or plastic and can have two forms: either to fold back the two wings at the same time, or to fold back only one wing at the same time.

Welding

When all leads are assembled, the network is solidarized while dissolving a little tin on each intersection. Tin is the metal used for welding because it melts at a very low temperature (232°C). One uses it in the form of rods made up of a mixture with lead 40%. Olein is applied to each intersection using a brush or by impregnating the tin rod. This oil is used to pickle the surface of lead so that the welding adheres. Stearin is also used; it fulfills the same function as olein but it presents the aspect of a white waxy block which one rubs with the intersections. The soldering iron is an apparatus which produces heat towards a copper breakdown, it can be electric or with gas. The breakdown can be serious and of variable form.

The overlapping of the wings of leads is covered and dissimulated under tin. The welding is slightly bent without being too large. Its form is centered on the symmetrical intersection of way without being too spread out and the formed unit is homogeneous. The second face of the panel is then contresoudée except for the lead of entourage which is not it.

Cementing

This operation ensures the sealing and consolidates the stained glass. It remains discussed within the professionals because its long-term effects can deteriorate the quality of materials. When leads are welded, the panel is not yet hermetic. One fills fine spaces between glasses and leads using a Mastic liquid. This one is applied using a round brush so that it penetrates between the wings of leads and the surface of glass. This requires an intensive cleaning using of the Sciure and a Brosse with grass. This type of cementing is strongly disadvised in the case of an old panel having of the painted parts: one then exerts a cementing “with the finger” using same cement (prepared firmer); what avoids a contact on the totality of surfaces.

Cement is a composition containing and Linseed oil, of Precipitated chalk (of Spain, of Troyes) Siccatif (to accelerate drying). The panel dries then according to several alternatives, some not folding back the wings before cementing; one can also clean with newspaper, etc

The vocabulary

wing of lead: visible part of the rod of lead, variable width, maintaining the parts of glass.
heart of lead: bar transverse intern of lead (“H bars”), inserted, at the time of the lead setting, between the sections of the parts of glass.
barlotière: bar metal punt marrying the shape of the panels which it supports.
gauges: form out of strong paper, used as owner or gauge to cut out a part of glass.
paperboard of cut: Transfer paperboard of assembly on strong paper, cut out then in gauges.
paperboard of assembly: model life size of the stained glass, carrying the precise layout of the network of leads or copper.
scissors to be gauged: scissors with triple blades being used for cutting of the gauges, equipped with an additional blade for the center which detaches a paper band web thickness of lead or copper ribbon.
cive: circular part of glass of small size obtained by blowing, comprising one roves in the center.
chip of flagstone of glass: glare of flagstone of cut glass using a marteline.
color of cementing: Color made up of a metal dye of origin which, using a cement, or conveys, penetrates in the surface layers of glass and colors it after cooking.
vitrifiable color: Painting made up of a dye and a flux which, deposited on glass before cooking, is transformed by fusion into a vitreous matter forming a unit with glass.
cut with the measuring rod: Repetitive cut of parts of similar glass of form. One uses a measuring rod in the place of the strong paper gauge.
cut with the gauge: Cross carried out while following the contour of the gauges.
flagstone of glass: Part of glass of 30 X 20 cm and approximately 25 mm thickness, run in a mould and being used with the clothes industry as stained glasses assembled with the reinforced concrete or the epoxy resin.
enamel: vitrifiable color associating a transparent flux tinted using metallic oxides, which is used to color white glasses or to raise the color of coloured glasses.
melting: substance used to lower the melting point of the vitrifiable colors.
smear of leads: Carryforward on a sheet of paper of the lead network of a stained glass to be restored, obtained by pressing paper against leads and by rubbing it with a graphite stick to obtain a print.
fusing: cooking between 750 and 850°C several superimposed layers of glass, decorated glass support and glasses, to obtain their joining by fusion.
engraving with the acid: Surface devitrification of a part of glass under the action of hydrofluoric acid; process employed on flashed glass to obtain decorative effects by contrast of colors.
greyness: color vitrifiable black, brown, etc, made up of a pigment (metallic oxide) and of a flux. Diluted with the water distilled or the vinegar, and added with gum arabic to support its adherence on glass, it is cooked between 600 and 650°C.
to notch: to correct the inequalities of cut, or to carry out certain returning cuts, by corroding the edges of glass using a grip.
yellow of money: Color of cementing, not requiring a flux, made up of ocher and money salts, which penetrate in the surface layer of glass and color it of a transparent yellow.
cement: mix of and whiting linseed oil applied under the wings of leads of the stained glass to ensure the sealing and the rigidity of the panel.
put out of leads: operation consisting in engaging contours of each part of glass in the throats of the lead rods, then to fold back the wings against glass of them before undertaking the welding of the lead intersections.
panel: in a strict sense, each part of a stained glass delimited by a metal reinforcement.
lead of breakage: very thin lead used in restoration to maintain the fragments of a broken part.
given out of lead: replacement partial or complete of broken or damaged leads of an old stained glass by new leads.
network of leads: together leads of a panel or a canopy.
thermoforming: cooking of a part of glass on a support in relief beyond its melting point to give him a particular form.
small canes: metal stems being used to reinforce the maintenance of the panels, fixed by fasteners welded at the lead network.
vitrifiable: who can acquire a vitreous structure by cooking.

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