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Activity 002: Copper Foil Application and Soldering

Activity ID: U12M2-ACT-002 Duration: 45 minutes

Overview

Students apply copper foil to pre-cut and ground glass pieces, then solder them together into a small panel (4-6 pieces). This activity builds the core assembly skills for stained glass work: precise foil application, flux use, soldering iron control, and creating clean solder beads along foil seams.

Materials & Equipment Needed

  • Pre-cut and ground glass pieces (4-6 pieces per student, from Activity 001 or pre-prepared)
  • Copper foil tape (7/32 inch, adhesive-backed)
  • Fid or burnishing tool (plastic or wooden)
  • 60/40 solder (60% tin, 40% lead), solid wire
  • Oleic acid flux (liquid, in applicator bottle)
  • Temperature-controlled soldering irons (one per 2 students), set to 700-800°F
  • Soldering iron stands with heat-resistant sponge
  • Chisel tips (3/8 inch) for soldering irons
  • Flat work surface (plywood board, 12" x 12" minimum)
  • Push pins or glazier's points to hold pieces in position
  • Isopropyl alcohol and paper towels (for cleaning edges)
  • Nitrile gloves
  • Safety glasses
  • Ventilation fan or fume extractor positioned near work area
  • Wet sponge for iron tip cleaning

Instructions & Procedure

Part 1: Edge Preparation and Foil Application (15 minutes)

  1. Students clean all glass edges with isopropyl alcohol and paper towels — edges must be completely dry before foiling
  2. Instructor demonstrates copper foil application:
  3. Peel back 2 inches of backing
  4. Center the foil on the glass edge (equal overlap on both sides)
  5. Press foil onto edge, wrapping smoothly around corners
  6. Overlap the foil start by 1/4 inch when returning to the starting point
  7. Use the fid to burnish foil flat against both glass surfaces
  8. Students foil all pieces:
  9. Check for wrinkles, gaps, or bubbles — press out with fid
  10. Verify even overlap on both sides
  11. Ensure foil is firmly adhered (tug test — should not peel easily)
  12. Common errors to watch for:
  13. Foil not centered — uneven overlap
  14. Foil wrinkled at curves — needs slower, more careful application
  15. Foil lifting at corners — inadequate burnishing

Part 2: Panel Assembly and Tack Soldering (10 minutes)

  1. Students arrange foiled pieces on the work board according to their pattern
  2. Use push pins or glazier's points to hold pieces snugly together
  3. Instructor demonstrates tack soldering:
  4. Apply a small drop of flux to the junction point
  5. Touch solder wire to the iron tip to load a small bead
  6. Touch the loaded iron tip to the fluxed junction for 1-2 seconds
  7. Lift iron straight up — a small solder dot holds the pieces in place
  8. Students tack solder all junction points to lock the panel together
  9. Check panel alignment — tack joints can be reheated and adjusted if pieces shifted

Part 3: Full Seam Soldering (20 minutes)

  1. Instructor demonstrates seam soldering technique:
  2. Apply flux along the entire foil seam (thin, even coat)
  3. Feed solder wire to the iron tip while drawing the iron smoothly along the seam
  4. Speed and solder feed rate control bead height — slow and steady
  5. Ideal bead is slightly convex, smooth, and even width
  6. Students solder all seams on the front of the panel
  7. Flip panel carefully and solder all seams on the back
  8. Students inspect their work for:
  9. Smooth, even solder beads
  10. No gaps or cold joints (dull, rough solder indicates insufficient heat)
  11. No burned flux (black residue indicates iron was too hot or too slow)
  12. No glass cracks from excessive heat exposure

Discussion Points

  • What happened when you tried to solder without flux?
  • How did iron speed affect the solder bead quality?
  • What does a "cold joint" look like and what causes it?
  • Why is it important to solder both sides of the panel?
  • What ventilation considerations apply when soldering with lead solder?

Expected Outcomes

  • Students produce a 4-6 piece soldered panel with clean, even solder beads
  • Students demonstrate proper foil application with no wrinkles or gaps
  • Students can control soldering iron speed and solder feed rate to produce consistent beads
  • Students understand the role of flux and can identify cold joints vs. properly wetted joints

Assessment Rubric

Criteria Excellent (4) Proficient (3) Developing (2) Beginning (1)
Foil application Even overlap, no wrinkles, fully burnished Minor wrinkles, mostly even overlap Several wrinkles or gaps, uneven overlap Foil poorly applied, peeling or bunched
Tack soldering All junctions tacked, panel aligned correctly Most junctions tacked, minor alignment issues Some junctions missed, panel shifted Unable to produce tack joints
Seam soldering Smooth, even beads on both sides, no cold joints Mostly even beads, 1-2 minor imperfections Uneven beads, some cold joints or burned flux Solder does not adhere or major defects throughout
Safety and cleanup Proper ventilation, glasses worn, workspace cleaned Minor lapses, self-corrects Needs reminders about ventilation or PPE Multiple safety concerns

Safety Considerations

  • Safety glasses are mandatory — solder can spatter when contacting flux
  • Work in a well-ventilated area or use a fume extractor — lead solder produces fumes during soldering
  • Nitrile gloves recommended when handling flux and solder (lead exposure)
  • Never touch the soldering iron tip or recently soldered seams — thermal burn hazard
  • Keep the soldering iron in its stand when not actively in use
  • Wash hands thoroughly with soap and water after handling solder (lead contamination)
  • Do not eat, drink, or touch your face during or immediately after soldering without washing hands
  • Dispose of solder scraps and flux-contaminated materials properly — lead-containing waste

Last Updated: 2026-03-19