Came glasswork are windows in which the individual flat glass pieces are framed by U- and H-shaped lead rods and soldered together along the edges. Before it was possible to produce larger glass surfaces, rung and lead glass windows were the only way to glaze larger wall openings. Today they are mainly realized as artistic works. Despite the similarity of names, lead glass is not used in lead glass windows.
Came glasswork is the process of joining cut pieces of art glass through the use of came strips or foil into picturesque designs in a framework of soldered metal.
Final products include a wide range of glasswork, including stained glass and lead light pieces. Came is made of different metals, such as lead, zinc, brass and copper. The metal came selected generally depends upon the size, complexity and weight of the project. As an alternative to came, copper foil may be used, for small, intricate pieces.
Overview
Came glasswork includes assembling pieces of cut and possibly painted glass using came sections. The joints where the came meet are soldered to bind the sections. When all of the glass pieces have been put within came and a border put around the entire work, pieces are cemented and supported as needed. The work may be made waterproof by forcing a soft oily cement or mastic between the glass and the cames. A form of embellishment and gilding, such as Angel gilding and Eglomise, may be added to finish the piece.
Works may need to be reinforced, like large pieces or ones that will be exposed to the outdoor elements. Support can be provided as the piece is made through the use of reinforced and metal-covered lead came, the use of steel strips in the came channels, or use of rigid cames, such as copper, brass or zinc. Bars of steel or steel rebar may be attached to the back of finished works as reinforcement.
History
Theophilus Presbyter, the first to write about joining art glass using the came technique in the book De Divers Artibus. Theophilus was a Benedictine Monk who was a glass and pigment worker who practiced in the late 11th and early 12th centuries.
Came glasswork have been common in Europe since the High Middle Ages. Initially, this technique was only used for the windows of the large cathedrals. Lead glass windows are an important feature of the Gothic style. From the late Middle Ages, however, more and more profane buildings were also equipped with stained glass.
The process of assembling a larger glass surface from small pieces is due to the difficulty in cooling liquid glass in a larger surface so that it does not crack. Larger glass surfaces were only possible with the production of genuine antique glass. Flat glass solved this problem entirely. This left the glassmakers of the Middle Ages only the way to produce small panes of glass and to connect and cement them using lead rods. By using differently colored pieces of glass, picture windows were created that transformed the apparent disadvantage into a separate art form. The technical structure of the lead rods is a special “graphic” design tool. The fragments were often made with black solderand worked silver yellow to achieve fine contours, shadow effects and yellow spots.
The middle part of a lead glass pane painted with glaze paints is called the cabinet pane.
Came glasswork are still made today for sacred and secular buildings.
Technology
Materials
Materials to complete a glasswork project may include the pattern, cut glass, came, wood trim, solder, cement. Additional supplies include newspaper, cutter oil, a plywood board, masking tape, flux, and whiting.
Glass
Mouth-blown glasses are, for example, real antique glass andreal antique flashed glass. New antique glass,Goethe glass, cathedral glass, opalescent glass and Gdansk glass are glasses made in the table cast-roll process. Ornamental glass and float glass are produced using the drawing process. A special form are slice discs (moon discs ), manufactured using centrifugal technology. Antique glass isblown into a hollow cylinderwith a glassmaker’s pipe, cut lengthways with red-hot iron, squeegee rolled up, stretched and tempered in the oven. This creates a lively surface with streaks and bubbles; these arise from the doctor blade.
Came
Lead came is often supplied in lengths of 2 m and in widths of differing sizes. It also comes in flat or domed profiles.
Brass and copper
Brass and copper have been used to bring a copper or golden hue to the works. Generally, though, they were used only for windows between about 1890 and 1920. Both metals were often alternatives to zinc for Frank Lloyd Wright designed windows.
Brass-capped lead
Brass-capped lead is another type of came used for glasswork projects.
Lead
The soft, malleable lead (lead rods) is ideally suited for connecting pieces of glass to one another, but is not very resilient as a load-bearing element and backbone of the glazing. Steel inlays can significantly increase the stability of the lead fields. Alternatively, galvanized flat steel tap wrenches can be soldered on. About two meters long lead rods are drawn in several widths from so-called broken lead, which have different profiles and different lead cores.
The traditional method of creating “camework glass” uses lead came, which ages into a dark blue-gray patina. In comparison to other came metal strips, like brass, copper and zinc, lead is softer and more flexible, making it easier to cut and bend. It’s also inexpensive and durable. A downside is that the finished projects may be prone to sagging due to lead’s softness. This can be mitigated somewhat by stretching the lead to make it more rigid before it is used. Special precautions should be taken when working with this metal came to avoid to lead contamination.
The lead came windows of the medieval churches are sturdier than those of the 19th century and much of the 20th century. The composition of lead came changed over time, at first by removing other metals to make a “pure lead” and then again during war years when lead was needed for ammunition. Since the 1970s a new form of lead, restoration lead, was developed based upon medieval lead’s metal composition. Restoration lead is stronger than lead came of the prior 100 years or so.
Water tightness is achieved by brushing cement under the flanges of the leads to both faces prior to installation or by applying putty afterwards. Typically the cement consisted of linseed oil, whiting, lamp black and white spirit.
Zinc
Zinc makes a lightweight, strong and rigid came, which lends itself to glasswork projects that don’t have many curved lines, are large, or have a number of straight lines that require greater support than lead would afford. Zinc accepts finishes, such as black and copper. Because of its strength, zinc is often used for border cames, which are U-channel cames for the outside edges.
Frank Lloyd Wright used zinc came for his stained glass windows. Beveled glass work is generally done in zinc came, primarily because of its ability to manage the weight of heavy plate glass; whereas beveled glass works made of lead came are much more likely to buckle or sag over time.
Soldering tin
Soldering tin consists of 60% tin and 40% lead. Its melting point is 100 ° C lower than that of lead, so that it is possible to connect two lead rods together without the lead melting. Stearin oil, stearin wax and solder paste are used as solder.
Copper foil
Copper foil is an easy, versatile alternative to came and is particularly useful for small projects. Using copper foil, the edges of the glass pieces are wrapped with adhesive copper tape and soldered together along the adjacent copper strips. A patent for the method of “Joining Glass Mosaics” was issued to Sanford Bray in 1886, This new method of joining pieces of stained glass used copper/copper foil instead of lead sashes. By using copper foil, one could now make cylinders, cones, and globe-shaped shades or many other irregular forms.
Putty
To make lead glass windows watertight and more stable, spread the lead cheeks with putty. Alternatively, a liquid is stirred paste of is linseed oil, chalk, carbon black and turpentine or mineral spirits painted on the inner side cheeks of the lead rod prior to insertion of the glass to seal the joints.
Tools
Stencil scissors and stencil knives have double blades at a distance of 1.5 mm. This corresponds to the thickness of the lead core. If you cut the templates with normal scissors, they would be too big. Stencil scissors and knives cut a thin strip out of the box, after which the glass is cut.
To cut the glasses there is the glass cutter with a steel wheel or a cutting diamond. The cutting slide allows straight cuts to be made, with the circular cutter you can create circles.
With the glass hammer or the metal handle of the glass cutter, you can start the cut from below after cutting so that the glass can be separated more easily.
Crumb tongs and grindstone are used to straighten irregular edges and remove the burr.
The lead is cut into pieces with the lead knife and widened a little with the lead applicator so that the disks can be pushed more easily into the profile. Glass nails fix the glass pieces on the lead table.
The soldering iron heats the solder with which the lead rods are connected.
With the help of the putty knife or brushes, the soft putty gets under the lead cheeks.
Steps
The draft is usually created in 1:10 scale. It is important to have clear lines that are appropriate for the material. Small areas and shapes that are difficult to cut are unfavorable. After the design drawing, the artist creates the cardboard box. In original size, he determines the lead lines, the thickness of the lead rods and the preliminary color scheme and marks the areas for etching or grinding work. In the lead crack, the glazier fixes the lead sprouts, whereby the lead is calculated based on the folding of the frame.
The lead crack forms the template for the stencils made of strong paper; they are numbered as the lead field can be inserted or numbered from top to bottom right. Using stencil scissors or a stencil knife, the glazier cuts the lines and places the finished parts on the design again.
Now he selects the colored glasses and assigns them to the templates. He places them on a glass pane to save space, cuts along the edge of the template with the glass cutter and breaks the piece off with his hands. Burrs or tips are defused with crumble tongs or grindstone.
Deviating from this technique, it is possible to work without a box and templates. If the glass pieces are cut freely, shape and color can be changed at any time. The exact outlines of the lead fields are drawn on large glass sheets and the cutting lines of the glasses are sketched on them. The glass pieces are cut together like a mosaic and adjusted to the panes next to them. With this free improvisation, constant reviewing and changing, you are not hampered by initial determinations. With this method of clearing, Josef Oberberger designed the windows in Augsburg Cathedral and Regensburg Cathedral, for example.
After the glass cutting begins leaded. On a large lead table, two flat stop bars are nailed right and left at the front. The glazier first places two edge sheets or edge sheets on these. He pushes the first piece of glass into a lead and fixes it with a nail. A piece of inner lead is compressed and led to the glass so that it encloses the piece with one side of the H-shaped profile.
Protruding ends are cut off sharply at the edge of the glass with the lead knife and again compressed by placing a lead knife under the hammer. This work is continued through to the end through the last two lead leads, whereupon the glazier fixes the window with wooden strips. Now puts something on the connection points of the pencil piecesSolder and sets with solder and a hot soldering iron a flat, sufficiently large soldering point. When all the lead rods are firmly connected in this way, he repeats the whole thing on the back of the lead field. Putty can be placed in the open lead profiles to make it more stable. These are then deleted. Particularly stiff the window by completely is tinning of lead sprouts. Steel inserts or tap wrenches provide additional strength.
Finally, the window is cleaned with petroleum, chalk or sawdust. When the picture is intended for hanging, loops made of copper wire or lead are attached. Most of the time, however, it is inserted into a folded frame made of wood, metal or stone. This technique is also used in stained glass, in which the panes are painted and burned with black solder and enamel before they are left.
Preservation and restoration
In the event of glass breakage, weather-related damage or restoration of old glass windows, it is important to preserve the existing substance as much as possible. Jumps can be glued or secured with jump lead. Dirty glasses must be cleaned very gently so as not to damage any painting and the glass surface. Missing pieces of glass are added true to the original, as are destroyed parts of the lead network.