Came glasswork

This article is on the techniques of lead-came and copper-foil glasswork. For a general overview of stained glass art, see stained glass.

A typical copper-foil Tiffany lamp, with a dragonfly design

Lead-came and Copper-foil glasswork are the arts and crafts of cutting colored glass and joining the pieces into picturesque designs.

The traditional method uses lead came. This is the method used for centuries in Europe, mainly in Religious buildings such as cathedrals, churches and monasteries, and also in aristocratic houses.

An alternative method, replacing the lead came with copper foil, was invented in the 19th century, enabling creation of three-dimensional works, in addition to two dimensional ones to which the lead-came method is limited. The copper-foil artwork is commonly called Tiffany stained glass, even though there is a debate about whether John La Farge or Louis Comfort Tiffany invented this alternative to lead-came glasswork.

Overview

In both lead-came and copper-foil glasswork a colorful design is created by the artist who joins pieces of stained glass panes that have been specially cut for the work.

In the lead-came method the pieces of glass are embedded into the channels of the came, and then the joints between the came strips are soldered together.

In the copper-foild method, the edges of the glass pieces are wrapped with copper adhesive tape, then soldered together along the whole length of the copper strip.

The process details

The steps in creation of Lead Came and Copper Foil Glasswork

Designing on paper

The first step for both techniques is to create a design on paper. You can create your own designs, or use the large selection of design books and software available.

The next step is to transfer the design to a piece of paper from which paper templates are cut out. Special pattern scissors are used, that cut out an extra thin strip of paper between the pieces, to compensate for the width of the lead-came or the copper-foil, that separates the pieces of glass in the final work. The scissors for lead-came work leave out a wider strip than for copper-foil.

A new technique in professional studios is to create a scale model watercolor for the window. This is then digitally photographed and placed into AutoCAD to match a technical drawing for the space. After measurements and other notations are applied, the full pattern is printed on a large-format printer.

Transferring the design to the glass

There are two schools for this step: one practices gluing the cut paper to the glass before cutting it, the other holds the cut paper to the glass, and uses a paint pen to mark the glass around the paper edges. In a high output glass studio, professionals simply hold the pattern piece tight to the glass and carefully follow the edge of the paper with the cutter head. This can only be done well with practice.

Cutting the glass

In this step the glass is scored using cutting oil and a steel or carbide wheel, making a tiny imperfection along which the glass is broken using glass pliers - when pressure is applied to the glass with the pliers, the glass snaps at the score line.

Grinding down the cut glass

The glass pieces obtained from the previous step have sharp edges, and are not 100% accurate in their shape. The glazier can either account for this inaccuracy while glazing with lead came or implement an electric glass grinder with a diamond-coated grinding wheel to smooth-off the glass pieces, and to give them their accurate shape. A carborundum stone can be used to take the sharp edge off as well. An alternative to the grinding wheel is a diamond ring saw which is used to cut pieces too hard to cut the old fashioned way, or that may take too long to realize.

Note: It is important to wear safety glasses while grinding or cutting glass.

---

This is where the processes for each of the two methods split. The next section describes the steps for the Lead-came method. The equivalent Copper-foil steps are described in the copper foiling section below.

Lead came

A 16th century lead-came glass window, church Notre Dame, Les Andelys, Normandy, France

The lead-came has channels into which the glass pieces are inserted. There are two types of lead-came: for the circumference of the design, came with a U-shaped cross-section may be used, as it takes glass only on one of its sides. More often, a glazier will use normal H shaped lead and fold in the ears on the unused side to keep waterproofing putty out. It also helps to have this small margin of lead that may be removed on site to better fit the size of a panel's location. For the middle of the design, came with an H-shaped cross-section is used, taking glass on both its sides. The middle part of the H is called the heart, which connect to the "ears" of the lead. The two surfaces on each end of the H are called the "face". Emphasis of selected joint lines can be obtained by using wider came for these joints.

Stretching and cutting the lead-came strips

The lead-came strips are stretched for straightening and stiffening them. They arrive in 5 foot pieces, but can sometimes be stretched to 6 feet. Then they are cut with nippers, or a Glazing knife, to pieces to fit the circumferences of the cut glass pieces.

Assembling the lead and glass

Schematic cross-section drawing of two glass pieces embedded in three lead came pieces: 1 - U-shaped came; 2 - H-shaped came; 3 - glass

Each piece of glass is set in place upon a glazing drawing, with came shaped around it to make a matrix. Horseshoe nails and scraps of lead are used to hold the already-assembled pieces to the work surface. Horseshoe nails are used, because the steel is not tempered, and therefore has less chance of breaking the edge of a piece of glass. Sometimes on a delicate piece, a scrap of lead will cushion the glass from the nail. The glass and lead are assembled gradually, beginning from one corner of the work, and building-up away from it. The ends of the came are tucked under the ears of the other lead it meets.

Soldering the lead joints

File:Lead came solder points.jpg

Solder points in lead-came glasswork

The lead-came is soldered at the joints between strips with a 60/40 lead/tin solder. This is in contrast to the copper-foil method described below, where the whole length of the copper strip is soldered. Ideally, when soldering a came joint, the solder will wick underneath the ear of one strip of came and connect to the came tucked below.

Cementing the lead and glass panel

The final step is applying a waterproofing putty made of linseed oil and chalk is forced in the space between the glass and lead, to strengthen and waterproof the work. Lastly, the ears are pressed down against the glass, securing the piece and further waterproofing the panel.

Adding reinforcement bars

Lead is one of the heaviest metals, and because of its malleability and ease of soldering, is perfect for the stained glass art. But because of this, stained glass panels can be very heavy. These windows from Zettler Studio of Munich, Bavaria were made in 1928 for a church in Philadelphia, now closed. One of these sections alone can easily weigh 80 lbs and use a matrix of 7 bars in some examples. Because of this, the original installer have included copper wires soldered onto the window to be twisted around bars set into the frame. These round bars and wires help carry the weight and prevent buckling, a fatal problem for stained glass windows if not caught. The copper wire method is obsolete now, though still used in historical preservation. A preferable technique is that of soldering a flat bar perpendicular to the window. The ends of this bar will set into the frame and prevent deflection.

• 
  A lead-came window that buckled because of lack of reinforcement bars
• 
  Front view of the buckled window shown on the left

Copper foiling

• 
  Glass pieces wrapped with copper-foil, before soldering
• 
  Soldering the copper-foil wrapped pieces
• The fully-soldered pieces
  The fully-soldered pieces
• 
  The finished work, after tinting with dark patina

The steps of the copper-foil process are depicted in the images above:

• Wrapping the glass pieces with adhesive copper-foil; this is similar to the lead-came method, where the edges are inserted into the came channels. The foil should be burnished onto all three glass surfaces with a wooden fid.
• Water-based flux is applied to all visible copper sparingly. Note: too hot of an iron will boil this flux inside of a joint, producing bubbles in the solder bead.
• Soldering the copper-wrapped edges; a bead of solder is run across every spot of visible copper foil, in contrast with the lead-came method, where only the edges are soldered. It helps to have thumbtacks and strips of wood on hand to hold all the pieces together while soldering.
• Tip: A good solder bead will have a slightly rounded profile. If it is too thin, the foil and solder can fold up, pulling the adhesive from the glass and compromising the strength of the piece.
• Tip: Also keep in mind that while soldering that you are sending heat into the whole piece, therefore if you linger with your iron in one place, you will melt the solder bead on the other side, and create a “bloom” of solder against the table. The back and forth flipping to fix these blooms has frustrated many novice stained glass crafters.
• Applying the finishing patinas to even-out color variations or to emphasize details. This is also useful to hide imperfections in a solder job, or to quickly achieve the natural black patina that all lead gets with age.

Note: As with lead-came, emphasis may also be achieved by choices in foil width.

Copper-foil glasswork Hanukkah menora

Tools and materials

General

• Safety glasses
• Glass panes
• Pattern-scissors
• Adhesive or paint pen
• Glass cutter
• Cutting oil
• Glass pliers
• Electric glass grinder with diamond-coated grinding wheel
• Soldering iron
• Solder
• Flux and Applicator brush

For lead-came work

• Lead-came
• Lead nippers
• Glazing hammer
• Fids (tapering pins)
• Cement for lead-came glass

For copper-foil work

• Copper-foil
• Patina

Other uses of the copper-foil technique

The three photos below show the use of this technique for fixing the glass jar of a candy vending machine.

The partly assembled jar; some of the broken pieces are still separate, wrapped with the copper-foil.

The fully soldered jar.

The jar back in the vending machine, with the solder given an "Antique Black" finish or "Patina".

See also

• Stained glass
• Favrile

External links

• Photographic and video instructions