Slide 003: Copper Foil and Lead Came Assembly¶

Slide Visual¶

Copper Foil and Lead Came Assembly

Slide Overview¶

This slide covers the two primary cold glass assembly methods -- copper foil (Tiffany method) and lead came -- including materials, technique, soldering, and when to select each method. Students learn the complete workflow from prepared glass pieces to finished, soldered panel.

Instruction Notes¶

Cold glass assembly joins individually cut and ground glass pieces into a finished panel or three-dimensional object. The two dominant methods -- copper foil and lead came -- serve different design needs and produce different aesthetic results. Every glass artist needs proficiency in both.

Copper Foil (Tiffany Method)¶

Copper foil technique (also called the Tiffany method, after Louis Comfort Tiffany who popularized it in the 1890s) wraps each glass piece with a thin strip of adhesive-backed copper tape. The foil overlaps onto both flat surfaces of the glass, creating a solderable metal border around every piece. When pieces are assembled, the overlapping foil edges are soldered together, creating a continuous metal matrix that holds the glass in place. The result is thin, delicate solder lines (approximately 1-2mm wide) that allow intricate detail and tight curves -- this is why Tiffany-style lamps with hundreds of small, curved pieces use this method.

Foil Application Process:

Surface preparation: Glass edges must be clean and dry -- any grinding residue, oils, or moisture prevents adhesive bonding. Wipe edges with isopropyl alcohol and allow to dry completely.
Foil selection: Standard foil width is 7/32" (5.5mm) for standard 3mm glass; 1/4" (6.4mm) for thicker glass or textured surfaces. Foil comes in copper-backed (standard), black-backed (for dark-colored glass where copper would show through), and silver-backed (for clear glass or mirrors).
Centering: The foil is centered on the glass edge with equal overlap on both sides. Begin at a corner or inconspicuous point, peel the paper backing, and press the adhesive firmly against the glass edge.
Burnishing: Pressure is applied with a fid (a small plastic or wooden burnishing tool) to ensure full adhesion. Press the foil flat against both glass surfaces, working from the edge outward. Wrinkles, bubbles, or gaps in the foil produce weak solder joints that fail under stress.
Corners and curves: At corners, fold the foil smoothly without tearing. On tight curves, use small relief cuts (tiny snips at the outer edge of the foil) to allow the foil to conform without wrinkling.

Soldering Copper Foil¶

Soldering copper foil uses 60/40 solder (60% tin, 40% lead) applied with a temperature-controlled soldering iron at approximately 700-800F (371-427C). Lead-free solder (typically 96.5% tin / 3.5% silver) is available but harder to work with -- higher melting point (430F / 221C vs. 374F / 190C for 60/40), less fluid flow, and requires more skill. Some educational programs are transitioning to lead-free for health reasons.

Flux (oleic acid-based for glass work) is applied to the foil surface immediately before soldering -- flux removes copper oxide so solder can wet the metal surface. Without flux, solder beads up and will not flow along the foil.

The iron tip should be broad and flat (chisel tip, typically 3/8" / 10mm) to distribute heat evenly. The technique is to flow solder along the foil seam in a single smooth motion, creating a slightly raised bead. The iron should move at approximately 1-2 inches per second -- fast enough that the glass does not absorb enough heat to crack, slow enough that solder flows and bonds properly.

Common Soldering Errors:

Error	Cause	Fix
Solder beads up, won't flow	Insufficient flux or contaminated foil	Apply more flux; clean foil with fine steel wool
Solder melts through gaps	Too hot or lingering too long	Reduce temperature; keep iron moving
Flat, thin solder lines	Iron too cool, not enough solder fed	Increase temperature; feed more solder wire
Glass cracks at solder joint	Excessive heat transfer	Work faster; let joint cool before soldering adjacent joint
Foil lifts during soldering	Poor adhesive bond	Re-burnish; ensure glass was clean and dry during foiling

Lead Came Assembly¶

Lead came is the traditional method used in architectural and church windows for centuries. Came is extruded lead strip with either an H-shaped cross section (for interior joints where glass fits on both sides) or U-shaped (for panel edges where glass fits on one side only). The heart (center web) is typically 1-2mm thick; the flanges are 4-6mm wide. Came is available in various widths from 3/16" to 1/2" -- wider came creates more prominent lines.

Lead came workflow:

Stretching: New came is stretched 1-2% of its length using a came stretcher or vise to straighten it and work-harden it slightly. Unstretched came is too soft and floppy to work with.
Cutting: Cut with a lead knife (rocking motion) or came saw (for precision). Never use scissors or tin snips -- they crush the came channels.
Fitting: Glass pieces are fitted into the came channels using a fid or plastic tool. Do not force glass into tight channels -- this cracks the glass. If the fit is too tight, widen the channel slightly with the fid.
Soldering joints: Where came strips meet, solder with 60/40 solder and oleic acid flux. Lead came joints are point-soldered (small, flat joints), not bead-soldered like copper foil.
Cementing: After soldering, press glazing cement (linseed oil-based putty mixed with lampblack and whiting) under the came flanges on both sides of the panel. Cement weatherproofs the panel and provides structural rigidity. Without cementing, lead came panels are fragile and leak in exterior installations.
Cleaning: Remove excess cement, clean glass surfaces, and apply patina if desired.

Choosing Between Methods¶

Factor	Copper Foil	Lead Came
Line width	Thin (1-2mm)	Wide (3-12mm)
Best for	Detail, curves, small pieces, 3D objects	Large panels, geometric designs, structural work
Strength	Moderate (reinforcement needed for large panels)	High (came provides structural framework)
Speed	Slower (each piece wrapped individually)	Faster for large panels with simple shapes
Skill level	Moderate -- foiling is tedious but forgiving	Higher -- came fitting requires practice
Outdoor use	Requires sealing and reinforcement	Traditional for exterior windows (with cement)

Lead Safety in Both Methods¶

Both methods produce lead-containing waste. 60/40 solder is 40% lead. Lead came is nearly pure lead. Students must wash hands thoroughly after any soldering or came work -- lead is absorbed through skin contact and hand-to-mouth transfer. Eating, drinking, and face-touching are prohibited during lead work. Work surfaces must be cleaned with a damp cloth (not swept, which aerosolizes lead dust). Lead waste goes in a designated hazardous waste container, not regular trash.

Key Talking Points¶

Copper foil allows intricate detail and tight curves; lead came provides structural strength for large panels
Glass must be clean and dry before foiling -- contamination causes adhesive failure
Standard foil: 7/32" for 3mm glass; center on edge with equal overlap on both sides
Solder is 60/40 (tin/lead); flux removes oxide for proper wetting; lead-free alternatives exist
Iron temperature and dwell time are critical -- too hot cracks glass, too cold won't flow
Lead came H-channel for interior joints, U-channel for edges
Lead came panels require cementing for weatherproofing and structural integrity
Both methods produce lead-containing waste -- proper handling, hygiene, and disposal required
Never eat, drink, or touch your face during or after soldering/came work without washing hands

Learning Objectives (Concept Check)¶

[ ] Can the student explain when to choose copper foil vs. lead came for a given project?
[ ] Can the student describe the foil application process and common failure modes?
[ ] Can the student identify the role of flux, correct solder composition, and iron temperature?
[ ] Can the student demonstrate correct soldering technique with appropriate speed and pressure?
[ ] Can the student explain the lead safety protocols for both assembly methods?

Adaptations for Different Learning Styles¶

Visual Learners¶

Cross-section diagrams: copper foil wrapping around glass edge (showing overlap), lead came H-channel and U-channel with glass fitted inside
Before/after photos: foiled pieces before soldering, flat solder bead vs. raised bead, properly cemented came panel
Video of soldering technique showing iron movement speed and solder feed rate
Side-by-side comparison of finished copper foil panel vs. finished lead came panel

Kinesthetic Learners¶

Foiling practice: each student wraps at least 5 pieces before attempting soldering
Soldering practice on scrap: students solder foiled scrap pieces together before working on their project
Came fitting exercise: fit pre-cut glass into pre-cut came sections to develop the feel for correct fit vs. too tight
Cement application: students apply cement to a small sample panel and clean it

Auditory Learners¶

Soldering by sound: the sizzle of flux activating tells you the iron is hot enough and the flux is working
Talk-through: "I'm feeding solder at the front edge of the iron, moving at about 1 inch per second... hear that light sizzle? That's the flux cleaning the copper."
Discussion: "Why did Tiffany use copper foil for lamps instead of lead came?" (Answer: foil allows the tight curves and small pieces needed for detailed lampshade designs; came is too rigid)

Reading/Writing Learners¶

Soldering parameter reference card: iron temperature, solder type, flux type, speed, common errors
Written comparison: "List three advantages and three disadvantages of copper foil vs. lead came"
Project planning worksheet: given a design, students choose the assembly method and justify their choice in writing

Standards and References¶

OSHA 29 CFR 1910.1025 - Lead Standards for General Industry: - PEL for airborne lead: 50 ug/m3 as 8-hour TWA - Action level: 30 ug/m3 (triggers monitoring and medical surveillance) - Requires hygiene facilities (handwashing) in lead work areas - Prohibits eating, drinking, smoking in lead work areas

EPA 40 CFR 261 - RCRA Hazardous Waste Regulations: - Lead solder waste and lead came scraps may be classified as hazardous waste if lead content exceeds TCLP thresholds - Educational facilities should treat all lead waste as hazardous and use proper disposal channels

OSHA 29 CFR 1910.252 - Welding, Cutting, and Brazing: - Soldering operations fall under this standard - Requires adequate ventilation to prevent inhalation of solder fumes - Flux fumes are irritants and may trigger respiratory sensitivity

ASTM B32 - Standard Specification for Solder Metal: - Defines the composition and quality requirements for 60/40 and other solder alloys - Specifies melting ranges and mechanical properties

Session Details¶

Time Allocation: 40 minutes (15 min demonstration + 25 min supervised practice)
Breakpoints for Discussion:
After foil application demo: "What happens if the glass edge is still wet from grinding when you apply foil?" (Answer: adhesive fails; foil peels during soldering; solder joint fails)
After soldering demo: "Why do I keep the iron moving instead of holding it in one spot?" (Answer: glass absorbs heat from the solder joint; lingering transfers enough heat to crack the glass)
After came introduction: "Why does lead came need cementing but copper foil doesn't?" (Answer: came channels have gaps where air and water penetrate; foil bonds directly to glass with no gaps)
After lead safety: "What's the most common way students get lead exposure?" (Answer: hand-to-mouth transfer -- touching lead, then eating without washing hands)

Discussion Prompts¶

Design Decision: "You're designing a 4-foot x 6-foot window for a church. Which method do you use and why? What if the design includes 200 small curved pieces?"
Material Evolution: "Lead-free solder is becoming standard in electronics. Should we transition to lead-free in stained glass? What are the trade-offs?"
Historical Context: "Stained glass windows from medieval cathedrals (lead came) have survived 800+ years. Modern Tiffany reproductions (copper foil) are 100 years old. What does this tell you about durability?"
Safety Culture: "A student tells you they've been doing stained glass at home for years without gloves and 'they're fine.' How do you respond?" (Answer: lead exposure is cumulative with no acute symptoms; blood lead testing is the only way to know exposure level)

Instructor Notes¶

Have students wash hands immediately after any soldering or came work -- make this a non-negotiable end-of-session routine
Ventilation is critical during soldering: flux fumes are irritating, solder fumes contain lead particulate. Ensure exhaust fan is running before any iron is turned on
Common beginner frustration with copper foil: the foil tears or wrinkles on curves. Solution is patience and practice -- demonstrate the relief cut technique for tight curves
Soldering is the single most anxiety-producing skill for new students. Start with "tacking" (small solder dots to hold pieces in position) before attempting full bead soldering. Build confidence incrementally.
Keep iron tip clean by wiping on a damp sponge between joints -- a contaminated tip transfers heat poorly and produces ugly joints
SAFETY CALLOUT: The soldering iron is 700-800F. Always return it to its stand between uses. Never set a hot iron on the work surface. Burns from soldering irons are the most common injury in stained glass classes.

Common Misconceptions Corrected¶

Myth: "More solder makes a stronger joint." Reality: Excess solder adds weight and stress without adding strength. A properly flowed bead is thin, even, and covers the foil completely. Thick blobs are cosmetically poor and structurally no better.
Myth: "Copper foil is easier than lead came." Reality: Foiling each individual piece is tedious and time-consuming. Lead came assembly is actually faster for simple geometric panels. Copper foil's advantage is in complex, curved designs -- not in ease.
Myth: "You can use any solder for stained glass." Reality: 60/40 (or 50/50 for came work) is the standard. Plumbing solder (which may contain acid flux) damages glass. Electronics solder (rosin core) produces toxic fumes. Use only solder designed for stained glass with oleic acid flux.
Myth: "Lead came is obsolete." Reality: Lead came remains the standard for architectural and restoration stained glass work worldwide. It provides structural strength that copper foil cannot match for large panels.

Accommodations for Neurodiversity¶

ADHD Support¶

Break the lesson into distinct segments: foiling demo (5 min) -> foiling practice (10 min) -> soldering demo (5 min) -> soldering practice (15 min)
Foiling is repetitive -- provide variety by having students foil pieces of different shapes rather than identical rectangles
The tactile and visual reward of a completed solder bead provides immediate gratification that supports engagement

Autism Spectrum Support¶

Provide a numbered, step-by-step foiling procedure card: 1) Clean edge, 2) Select foil width, 3) Peel backing, 4) Center on edge, 5) Press with fid, 6) Burnish flat
Soldering temperature and speed can be expressed as exact values: "Iron at 750F, move at 1 inch per second, feed solder at 1 inch per second"
The systematic nature of panel assembly (fit pieces, foil, tack, full solder, clean) maps well to rule-based thinking

Dyslexia Support¶

Photo-based instruction cards for both foiling and soldering sequences
Color-coded foil types: copper = no mark, black-backed = black dot sticker on roll, silver-backed = silver dot sticker
Soldering error chart uses photographs rather than text descriptions

Sensory Processing Support¶

Soldering produces a sizzling sound and flux smoke -- warn students before demonstrating
Flux fumes have a distinctive smell that some students find unpleasant or triggering -- ensure ventilation is adequate and position sensitive students upwind
The soldering iron radiates significant heat -- some students may need to work at a greater distance and approach the iron position gradually

Last Updated: 2026-03-19 Content Review: Q1 2026