Copper foil vs lead came: picking a technique
Every pattern on this site can be built with either copper foil or lead came; picking one changes the cutting margin subtracted from each piece and the final look of the leading lines, not the underlying cut geometry.
Copper foil
Copper foil wraps each piece edge in a thin adhesive copper tape, then solders the seams into a rounded bead. The cutting margin is small, 0.03125 in per edge on this site's patterns, so foil suits patterns with narrow pieces or tight curves, and gives thinner, more detailed leading lines. Foil work is typically done flat on a table.
Lead came
Lead came is a grooved metal strip that each piece edge slides into before the joints are soldered. The cutting margin is larger, 0.1875 in per edge here, since the piece has to sit inside the came channel rather than butt against a thin tape edge. Came suits larger panels and simpler, bolder pieces, and gives a heavier, wider leading line.
Which one for your first pattern
If you are following the beginner guide, start with copper foil: the tools are lighter, the technique is easier to learn flat on a table, and it works on every pattern in the collection including the ones with curves, like Crescent Moon.
Every download on this site includes a cutting-margin pattern generated for your chosen technique, so the margin is already built into the piece you cut, not something to calculate by hand.
Lead came
Came holds pieces in a channel, so the leading line is set by the came width rather than by how you solder. It builds faster on large panels with long straight runs, it is stronger over a wide span, and it is the traditional answer for windows. It takes a wider margin off each piece, it does not follow tight curves willingly, and finished panels need cementing to make them rigid and weatherproof.
Choosing for the pattern in front of you
- Many small pieces, tight curves, a three dimensional object: copper foil
- Large panel, long straight lines, exterior window: lead came
- Fine detail you want the leading to disappear into: foil, with the narrowest tape that will hold
- A panel that must carry its own weight over a span: came, with reinforcement bars
Why the choice comes before the download
The two techniques subtract different margins from every piece, and the file is generated with that margin already applied. Picking the technique at checkout is what makes the printed pattern cuttable as printed, with no mental arithmetic at the cutting table. If you change your mind, the pattern can be rebuilt for the other technique on request.
Bench procedure and order of work
For copper foil, cut all glass first, then grind only enough to remove sharp points and make the piece match the paper line. Wash and dry the pieces before taping, because grinding slurry under foil causes lifted seams during soldering. Center the tape on the edge, press it down with a fid or a hard plastic tool, and burnish both faces until the adhesive no longer looks pale. Tack solder the panel at outside corners and at every 4 to 6 in along long seams, then solder full seams from the center outward so heat does not push small pieces out of line.
For lead came, build against two fixed straight edges on the board. Place the first border came, add the first glass piece, cut the next came with a miter or a square end as required, and continue across the panel. Use horseshoe nails or push pins close to the glass, not through the heart of the came. Solder only where came meets came. Cementing comes after soldering, and the panel should lie flat for at least 24 hours before handling hard.
- Keep a dry fit gap near 1 mm or less for foil, because solder is not a structural filler.
- Keep came joints tight enough that the solder bridge is short, usually under 2 mm.
- Check overall size after every 3 or 4 rows on a rectangular panel.
- Clean flux the same day, because dried flux can stain glass and metal.
Equipment, dimensions, and working figures
The same cutter, running pliers, grozer, grinder, pattern shears, and layout board can serve both methods. The different items are the wrapping or channel material, the way pieces are held, and the finishing steps. If you are still setting up a bench, compare the basic sequence with the beginner stained glass guide before choosing tools that only serve one method.
| Work item | Copper foil figure | Lead came figure |
|---|---|---|
| Edge allowance already in this site files | 0.03125 in per edge | 0.1875 in per edge |
| Typical useful piece clearance during dry fit | About 0.5 to 1 mm | About 1 to 2 mm inside the channel |
| Common bench check interval | After every 6 to 10 pieces | After every 3 to 4 rows |
| Small panel soldering time after cutting | About 1 to 3 hours for 40 to 80 pieces | About 30 to 90 minutes for a simple panel before cement |
| Post solder wait before firm handling | When cool and washed, often under 1 hour | After cement starts to set, commonly 24 hours or more |
Use these figures as shop checks, not as product specifications. Glass thickness, texture, and the exact metal chosen change the feel. Pattern size also matters, so calculate sheet area before buying glass with the glass quantity guide.
Frequent mistakes and practical recovery
If a foiled piece is too large, do not force it into the layout. Grind the high spot, wash it, dry it, and replace the foil if the edge tape has become torn or loose. If it is too small by less than about 1 mm on one edge, it can often remain in the panel if the surrounding gaps are even. If it is visibly short at a point or corner, recut it. A large solder blob over a bad gap will look heavy and can crack later.
If foil is off center, peel it back immediately and retape. After burnishing, adhesive usually stretches and leaves residue, so fresh tape is faster than repair. If solder refuses to flow, stop adding solder. Clean the seam, apply fresh flux, reheat a short section, and move steadily. Prolonged heat can break glass, especially on narrow tips.
For came, a common error is trimming each piece of came slightly long. The panel then grows across the board. Recover by reopening the last few joints and shortening the came, not by grinding all later glass smaller. If a came joint opens during soldering, hold the joint closed with a nail or clamp until the solder freezes. If cement squeezes onto textured glass, remove it before it hardens with a dry brush and a pointed wood stick, not a steel tool that can scratch the surface.
Special cases that change the choice
Deep inside curves, needle points, lettering, feathers, and small eyes are usually safer with foil because the metal can follow short changes of direction. Before resizing such a pattern, check that the thinnest bridge of glass will still be cuttable. The rules in the cuttable pattern guide are useful for judging those weak areas.
Exterior panels, doors, sidelights, and any panel that may flex need more than a neat seam. Lead came normally needs cement, perimeter support, and sometimes separate reinforcement. Foil panels can also need reinforcement when they are wide, tall, or hung from only two points. A useful shop warning is any panel over about 18 in in either direction, or any long unsupported strip of glass under about 1 in wide.
Three dimensional work, lamps, boxes, and ornaments are special cases because the seams become part of the structure. Foil is usually the practical method there, since the wrapped edges can be soldered at changing angles. Came is a poor fit where several planes meet at a sharp corner, unless the design is planned around rigid channels and simple geometry.
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