The copper foil technique, method made popular by L.C. Tiffany at the turn of the century, involves wrapping the pieces of glass with copper foil and soldering them together along the length of the seams.

Copper foil can be used as an alternative to lead in any instance at the personal preference of the user. It is much stronger than lead when soldered, needs no putty, is waterproof, and allows you to do intricately detailed projects where the bulky look and weight of lead would detract from the aesthetics of a delicate design.

The copper needed for this technique is of a thin, foil-like gauge. It has an adhesive on one side and is backed by protective paper. Copper foil is sold in 36-yard rolls and is available in several widths and gauges. Some of the common sizes used are 5/32", 3/16", 7/32", 1/4", 5/16", and 3/8". The actual gauge of the copper can be 1 mil, 1-1/4, or 1-1/2 mil. the thickness of the glass you are using and the finished look you want to achieve will dictate your choice.

For instance, if you use very wide foil such as 3/8" to wrap thin glass, you will have very wide seams in your finished project. Wide foils such as 5/16" and 3/8" are usually used where strength is an important factor or when very thick glass is being used. Beginners using standard 1/8" thick machine-made stained glass should start with 1/4" or 7/32" foil. These sizes are easy for the novice to handle. With a little more experience at cutting, you may like the narrow seams that 3/16" foil produces. The choice of width and milage is one of personal preference. As you do more stained glass, you will find that you have definite preferences.

The allowance between your pieces of glass using the copper foil method is 1/32". This means that the lines of your pattern should be 1/32" thick. This allowance is the space that your copper foil takes up. When cutting using the traditional method, you must cut every piece of glass to the inside of these lines. If you use the paper pattern method this allowance is cut out of the pattern. If you are using a full-size pattern that is drawn with 1/16" lines, and using the traditional method, cut slightly to the inside of these lines.

TOOLS FOR THE COPPER FOIL METHOD
Listed here are the tools and supplies you will need for the copper foil method. Some tools are optional, while others are absolute necessities. Optional items are marked with an asterisk (*).

glass cutter lubricant breaking pliers *running pliers
*grozing pliers *lathkin or fid *foil pattern shears soldering iron
sponge carborundum stone safety glasses ruler or straight edge
*circle or lens cutter *light box or table bench brush oaktag or file folder
scissors carbon paper solder flux and brush
copper wire glass marking pen *patina pattern paper
masking tape workboard/table lath strips *diamond bit grinder
stained glass copper foil APPLICATION OF COPPER FOIL
After all of the pieces of glass in your project are cut and refined to fit properly, you are ready to begin foiling. Every piece of glass must be wrapped in copper foil. Before you begin it is important that your glass is clean and free of dirt and oil from your cutter or the foil will not adhere properly.

Step 1. Remove the protective paper backing of the foil as you work. First, center the glass on the foil. Make sure that there is an even amount of overhang on each side of the glass. Wrap the foil around each piece of glass, overlapping it at least 1/4" from where you began. Cut off the excess with scissors.
Step 2. Crimp the foil around the edges of the glass. With a blunt piece of wood or a fid, burnish the foil on both sides of the glass and along the outside edge so that the foil adheres to the glass firmly and smoothly. A sloppy wrap job will ruin the appearance and affect the strength of the finished project.
Step 3. After wrapping and burnishing all of the pieces of glass, position them on your pattern. As with the lead came method, use lath strips to keep your panel squared up. Freeform projects can be held in place with horseshoe nails or push pins.
Step 4. Apply flux to the foiled seam joints.
Step 5. Tack solder to all of the joints in your project. Melt just enough solder onto each joint to hold the pieces firmly together so that they will not slip or slide apart. Neat, skillful soldering is not necessary at this point because during the next step the tacking will be remelted.
Step 6. Apply flux along the foiled seams of the project that you will be soldering during this work session. If you apply flux to the copper and leave it unsoldered for too long, it will result in badly tarnished, oxidized foil that will be difficult, or impossible to solder without a thorough cleaning. Should this happens, you can remove the oxidation with a soupy mixture of water, vinegar, and table salt.
Step 7. The final soldering step is called "beading." This process involves building up the solder to a uniformly rounded bead along all the seams. Move the iron (with the tip held horizontal to the seam) and the solder continuously along the length of the seam. Remember that you can't bead a seam if you don't use enough solder. Likewise, too much solder will be difficult to uniformly bead. You will learn the proper amount to use through practice and experience. Bead both sides of your project.
Step 8. If you are not going to frame your panel in a wooden frame or U lead came, you will want to take the outside edges have a more finished appearance. You now want to bead the perimeter. First apply a very light coat of solder to the perimeter on both sides of the piece. This is called "tinning."
Step 9. Now bead the edges. This is accomplished by holding the edges to be soldered perfectly horizontal to the table. Melt just enough solder on the edge so that it "rolls" down over the sides of the foil, uniformly rounding the edge. This adds strength and a more professional look to your work. Please note that on curved edges you can only bead about 1/2" at a time; then carefully allow the solder to set, and slowly turn the piece so that every 1/2" section you are working on is horizontal to your work surface.
Step 10. If you are not going to frame your project, solder on loops for hanging at this time. Pre-formed circles of brass or copper can be purchased from your supplier or you can make you own simply by curling 18 or 20 gauge brass or copper wire around a dowel.
Wash your project in warm water and mild detergents to remove the flux or use a commercially prepared flux remover. You are now ready to apply patina to the solder. Patina changes the silver color of the solder to an antique black or copper. Commercially approved chemical mixtures are available. Wear rubber gloves to protect your hands from the chemicals, and follow the directions on the label. When finished, wash and dry your panel.
SOLDERING PROBLEMS AND TIPS PROBLEM PROBABLE CAUSE
Solder falls through seams to other side when soldering copper foiled pieces. Soldering iron is too hot or you are holding the iron in one area too long. Put a damp rag or sponge under the area you are soldering.
Beading of seams is too flat. Not enough solder.
Beading is lumpy -- peaks instead of flowing. Iron is too cold.
Can't seam to get beading smooth. Wrong kind of solder for job. Did you flux? Iron too cold or too hot. Too much or not enough solder.
Solder won't stick to copper foil or lead. Did you flux? Copper foil may be oxidized; clean with vinegar, salt, and water solution. Lead may be oxidized; wipe clean, dry, and rub with fine steel wool or wire brush.
Solder splatters into little balls all over the glass. Iron too hot; purchase rheostat for your iron. This will control the current to your iron and control the heat output.
Lead came melts and disappears before your eyes. Directly touching the lead came with a very hot iron. Position solder at joint, iron on top. Let solder flow down on lead came.