Copper Foil Technique

by Paul Wilson

My view about stained glass, is that there are two overlapping skills required that often culminates in what many regard as art. If either skill is missing or deficient, it will be just a piece of stained glass work, not art. The first required skill is the craftsmanship; rather, the use of tools and consumable supplies that go into building the project. This part requires technique, practice, and patience. Good hand-eye coordination is very important.

The second, and possibly more elusive requirement for some, is the optimum choosing of glass and marking it using pattern pieces with a marker prior to cutting. You can select your glass pieces for minimum waste, or you can select them for the best effect. Examples of this would be when using a solid color or clear glass that is known as a cathedral, which does not have texture or grain. You might squeeze each piece as close together as you can to eliminate waste because the glass is essentially the same at any angle.

Alternately, consideration must be given to best effect in some cases with textured glass or glass that has different colors worked through it in a pattern. (see SECTION VIII for details on selecting glass) If you are working on the mane of a horse and using a baroque glass which has bold colored swirls through it, you will want to move your pattern pieces around picking out the best area and swirl direction for each piece. This wastes more glass, but the effect is fully worth it. You should check out some of the examples in pattern books or at your local store.

Another problem is the choosing of a color combination. Think of each project as a symphony of different glass pieces that work together. This process of selecting different colors and the use of different textures often decides whether something is OK looking, or is a work of art. Often the selection of several similar colors, as is the case with most Tiffany style lamps, is the desired effect, other times colors from opposite sides of the color wheel are called for. It all depends on the project. Beginners should pick patterns where they have pictorial examples to aid them in choosing glass. Glass Pattern Quarterly magazine even lists the glass manufacturer and part number with their projects.

If you don't believe me about the difference between a work of art and just work, visit a few craft fairs, flea markets, and craft stores. Look at the pieces you see. If the individual glass pieces strike you as wrong, or appear to not look right take a closer look at it, many things can be the cause. Perhaps the glass pieces were picked wrong. Maybe the glass pieces used front and back sides mixed together with no rhyme or reason. All cutting should be done from the smoothest side of the glass with the pattern pieces facing up. Putting some pattern pieces down for marking or cutting some pieces from the wrong side of the glass seriously mars the symmetry of the piece. Picking glass with the pattern or grain all going the same way detracts from what the project should be. If the general appearance or finish does not jump out at you, the piece was inadequately cleaned or polished and will probably fail over time. These things all combined make the difference between art, and just something to while away the hours. If you think about famous art, it is something that was created, not just made. This is true of painting, music, and stained glass. It stays in existence because it has a timeless quality that people admire. Sloppy workmanship or bad glass selection is not art, its junk.

There are two popular methods for assembling cut glass into a project, one that was popularized by L.C. Tiffany is commonly known as the copper foil technique. Copper foil makes use of thin copper tape usually about 1.5 mils thick or .0015 inches. This tape is sticky on one side and is applied to the edge of the glass. After two or more pieces are "foiled" they may be soldered together. The copper foil technique is suited to many types of projects and allows using small pieces of glass and the building of complex shapes like Tiffany style lamps, flat lamps as popularized by Frank Loyd Wright or three dimensional projects like handkerchief or jewelry boxes.

The other popular method of assembling glass is called "Lead-Came" which is the use of U-channel and H-channel shaped lead. (see SECTION IV) The pieces of lead-came are cut and shaped around the glass pieces and then soldered. Lead-Came comes in 6 foot pieces and in rolls. This method is more popular for building larger panels, and architectural uses in doors and windows because it is inherently stronger.

There are many different tools and ways of going about assembling your projects. This FAQ covers only some of the techniques. The correct way to do something is the way that works best for you. The newsgroup is there for this reason. It's a great source.

Before getting deep into the how-to of copper-foil, it is important to understand that proper preparation is vital to a well-crafted project. This is true at any stage in the process. Making accurate cuts on the glass and properly preparing it will result in success most of the time. Sloppy preparation, i.e. inaccurate cuts, poor fitting of adjacent surfaces, or inadequate cleaning prior to foiling are guaranteed to ruin your project.

Those that are new to this craft should use pre-existing or pre-made patterns for simple projects. Let me reemphasize as mentioned in SECTION II that you should get some common plate glass and make many practice cuts before blowing your money on stained glass. Practice cutting/breaking straight lines, curvy lines and numerous shapes. Try circles, squares, triangles and the outline of basic objects like a new Moon or baseball bat. Your first projects should use Cathedral Glass which is the clear usually colored type of glass used in churches. Later you can graduate to opalescent and specialty glasses with different surfaces. (see SECTION VIII)

Another tip for new crafters is to copy your pattern using a bold style of marker, and then cutting on the outside of the line. The next step is to use a grinder to carefully grind away the line until it just about disappears. Later you will grind it again to fit the pattern as you assemble the pieces. Many experienced crafters cut on the inside of the line and a minimum of grinding is necessary.

The reason a grinder is essential is that the tape sticks well only to clean flat surfaces. The use of a grinder should be considered a necessity. The use of Grozier pliers or a glass file to chew away or file large chunks of glass does little towards creating a good mating surface for the foil. I find that it creates problems as glass seems to break wherever it wants to when chewing away or filing away with some tool. When grinding, be sure that the bit stays lubricated with water or it will wear out faster.


It is generally recommended that beginners use 1/4" wide tape. Narrower tape can be used after you develop some skill at applying it. Wider tape is used mostly for special effect. I prefer silver backed tape most of the time or occasionally use black-backed if I am going to apply a black patina finish. I have seen others recommend copper-backed tape time and time again, probably because it is a dollor or two cheaper. I feel this is wrong because many beginner projects start with Cathedral glass, which you can see through. You end up with a silver finished outside from the soldering but the inside of the tape which is against the glass edge, has a copper finish which you can easily see.

It looks more professional with the slightly more expensive silver or black backed tape. Copper backed tape is fine if you plan on applying a bright copper patina to the outside, but not for beginners. Patina's are the result of using a caustic chemical on the solder to change it's finish color. Copper patinas are a little harder to apply. All patinas can erode, or be scratched or rubbed off.

Before you apply the tape, you need to ensure the glass is clean. I normally wipe it down with thinner or mineral spirits because glass cutters leave oil behind. Then I wipe it with a clean dry rag. To apply tape, center a piece of glass on the sticky side of the tape, slowly rotate the glass while feeding more tape to the edge. When you reach the end, overlap the tape ends by at least 1/8" to ensure that glass piece is trapped inside when soldered. Failure to keep the tape centered results in wide areas on one side of the glass and narrow areas on the other. When soldered, it gives a poor looking result. The overlapping tape pieces should always be on the inside of any glass piece to add strength. There are several optional tools that you can use to make this easier.

After applying the tape to the outside, it must be folded or crimped over. With square corners, many times I fold over the longer sides, and then fold the top flaps over in a kind of mitre looking joint. On rounded pieces I generally pinch the round corners first and then work my way around with two fingers on the outside, rubbing the tape onto the glass piece as it's rotated. On inside curves like a small new moon shape, the edges of the tape have to stretch somewhat so I slowly rub each side over a little at a time allowing it to stretch. Just shoving the tape hard over usually results in cracks. These stick out like a sore thumb after soldering.

The next step is burnishing. You may use a fid or a small piece of smooth wood to rub the tape down tight to the glass. Be sure to use a good amount of pressure. I burnish the outside edge first, and then each side. If not properly burnished onto a CLEAN surface, the tape will fail during soldering. This means a lot more time will be spent cleaning up than foiling.

To remove foil that is not sticking, or was put on so far out of alignment as to be unsightly, use your hobby knife with the blade almost flat, and scrape it hard against the tape, pulling the tape away. It is much easier to remove now, than after the piece is soldered.

The method for fitting the pieces together varies. Small "light catchers" can be pushed together and held in place with a few "push pins" pressed into your assembly board and then soldered. Tiffany style lamps often use a Styrofoam form and special color coded pins to hold the pieces down. Flat panels usually require layout blocks or strips of wood around the outside. Layout blocks are small L-shaped brackets which are held down with push pins. The idea is to maintain a square or rectangular outside shape as the pieces are laid out. Some method is required to hold pieces in position otherwise you will end up with lopsided looking projects. Horse shoe nails are used on many lead came projects because they have smooth sides that don't mar the came.

I do soldering in four stages.

  1. Spot soldering
  2. Flat soldering
  3. Bead solder the back side
  4. Bead solder the finished side.

Spot soldering is done by placing a drop of flux at key points and then putting a small amount of solder under the soldering iron tip and then touching it to each fluxed point. Continue until each key spot has been spot soldered. This will maintain the integrity of the piece as it is soldered.

Flat soldering is the process where each joint is fluxed and then soldered enough to fill in the gaps between the individual pieces. Good flux is vital, I use Q-tips with a liquid water based flux. It is not necessary to get a good bead at this time, merely to create a piece that is structurally sound. For this step I keep the iron almost flat as I move it with one hand, and feed solder onto the top of the iron tip with the other. Before each joint is started, I wipe the iron tip clean on a sponge and apply a small drop of solder underneath the tip to help start the flow.

A few words about irons and tips. A dry or dirty tip has a hard time starting soldering. Allowing your tip to stay dirty very long causes failure of the tip. I do NOT use sal ammoniac or any other specialized tip tinning compound. They give off corrosive gases that get inside the element and ruin the iron. Keeping the tip clean takes practice but is the best method. I use a Weller 80 watt iron with 1/4" chisel tip. My voltage control device is set to 65% of full power. I use a 60/40 ratio of tin/lead for my solder. When I shut the iron off, I add a large amount of solder to the tip. The theory is that the outside of the solder will corrode as it cools, rather than the tip on the inside. After it is turned on the next time, I scrub it with a rag with a few drops of flux on it, and clean the tip at each use.

Step 2 is to turn the piece over and create good bead joints on the back. This is done by fluxing again, and this time hold the iron at a 45 degree angle. Move the iron to the right with your right hand while feeding solder with the left hand. The proper speed across the joint must be maintained while supplying the right amount of solder. Moving too fast and the bead flattens out or the iron can't keep up enough heat and the solder gets stuck, too slow and the bead gets too fat and spills over. When I cross a perpendicular joint, I pause for a second to allow the other solder to liquefy, this prevents cold solder joints. That's where the solder turns gray or has a wrinkly look to it. It takes practice, but that's what beginning pieces are all about. Look over the piece looking for bad spots or where you pulled the iron away and left a little hook of solder sticking out. Dab flux on the spot and rest the iron tip there until the solder melts and you can slowly pull it up.

For the last step I do the same to the front of the piece.

Some people omit step 2. They spot solder, bead solder the front, and then the back. How you do it is probably a matter of experimentation. Try different methods and see whats best for you.

At this point you may think you are about finished. If the project you have built is well crafted, to ensure it remains this way and stands out, you have a few more things you need to do. There are several steps to cleaning and polishing your project. If not properly cleaned of flux and solder traces, the project will begin to corrode. This is caused by the flux, which attracts and holds moisture against the copper and lead. The solder will begin to take on a white powdery look outside, inside and largely unseen to the naked eye, it is beginning to fall apart. At the minimum, the project should be well cleaned within 24 hours, no longer.

The first step in cleaning is to use whiting powder (chalk dust) and a small bristle brush. Cover the project in the powder and let it sit a few minutes while it soaks up the flux, then scrub the entire project using the brush and the powder. Be sure to scrub in different directions. Then use a toothpick on any stubborn areas where little bits of solder or dirt adhere to the glass. Next wash it using a soap that is manufactured to remove flux and then dry it. Optionally you might want to also use 0000 steel wool to lightly go over the solder beads, particularly if your going to patina. This is the point you may want to patina it, following the directions on the bottle. The last step is to use a wax on it. I use a commercial glass wax, once again reading the directions on the bottle. Others tell me that J-wax or other waxes with carnuba work well too. The wax puts a protective layer over the solder and makes everything gleam. All stained glass works should be periodically cleaned and waxed to keep moisture out, and keep it looking nice.

Repairs: Every once in a while a piece of glass cracks because I spend too much time in one area while soldering, or the glass breaks because it is flawed. Often this is a piece that is not on the outside. It still needs to be repaired or the entire project is wasted.

REPAIR: The first thing to do is to score an "X" boldy across the bad piece. Then you support it with a large firm sponge or something of similar density underneath, and lightly tap the center of the X with something sharp. A large nail and small hammer work nicely. Once the glass is cracked enough, it can be pulled out carefully one piece at a time. Some glass pieces may be stubborn and need to remain in the project because of the foil glue, don't fight them. As long as you get enough glass out to get a foothold, you can start working on it. Remove the remainder of the glass and foil using the soldering iron and pliers, heating each area and as you go.

If you need to clean up the surfaces of the surrounding pieces, you can use desoldering braid which you can find at many Glass Suppliers and any Radio Shack. This is done by dipping the braid in flux and placing it over the part to be desoldered. Then you run the iron back and forth over the braid causing it to suck the excess solder up by capillary action. You can then scrub back and forth with a clean piece of braid and the iron tip to further clean it up. After this you can fit the new piece in, flux it, and solder it in like new.

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last updated 23 Aug'99
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