Soldering joins the foiled pieces and gives a foil panel its strength. In leaded work, solder joins the lead at each junction. The solder used in stained glass is a soft tin and lead alloy that flows at a low temperature, so it can be melted onto copper foil or lead without harming the glass.
Equipment
- Iron. Around 80 to 100 watts is common. A temperature-controlled iron keeps the heat steady, which matters more than raw power. Plumbing and electronics irons are usually too weak or too hard to control.
- Stand. The iron lives in the stand between uses and is never left lying on the bench.
- Tip. Keep it clean and tinned (coated with a thin film of solder). Wipe it on a brass pad or a damp sponge between joints.
- Solder. Use solder made for stained glass, normally 60 percent tin and 40 percent lead, which melts at a relatively low temperature and flows smoothly. Acid-core plumbing solder and electronics rosin-core solder are not suitable. Lead-free alternatives exist, but they melt at a higher temperature and flow differently, so they take some practice.
- Flux. Gel or paste flux stays where it is brushed. It cleans the metal so the solder bonds, and a small amount is enough. Too much produces extra fumes and can make the solder spit.
- Ventilation. A fume extractor, or an open window and a fan to move the fumes away from the face.
Method for foiled panels
- Lay out the foiled pieces on the bench and hold them in position with pins or a jig.
- Brush flux along the foil seams. Flux only what is about to be soldered.
- Tack the pieces together at the joints with a small blob of solder at each junction so the panel holds its shape.
- Brush flux over a seam, touch the solder to the foil and run the iron along it so the solder flows in a rounded line. Keep the iron moving at an even pace.
- Add more solder where the line is thin. Take the iron away before the solder gets too hot and runs.
- Turn the panel over and repeat on the other side.
- Finish the outer edge with a line of solder, and tin any wire or hanging loops that will be fitted.
The solder should sit as a smooth, slightly raised bead that follows the foil exactly. Hold the iron on the foil only as long as needed. Too much heat on one spot can crack the glass, make the foil lift or make the solder pool.
Method for leaded panels
Lead came melts at roughly 327 degrees Celsius, not far above the temperature needed to melt solder, so the iron must not linger. A touch of flux on each junction, a small amount of solder and a short contact from the iron are enough. Soldering is on the visible face first, and then the back. Details are on the leaded panel page.
Cleaning and finishing
- Wash off flux residue with warm water and a soft brush. Leaving it on will corrode the solder.
- Apply patina with a cotton swab if the lines should be black or copper coloured.
- Polish with a wax or polish and buff with a soft cloth.
Common faults
- Solder will not stick. Dirty foil, too little flux, a cold iron or a dirty tip.
- Solder is lumpy. The iron was dwelling, or too much solder was applied. Re-melt and spread it.
- Foil lifts. The area was overheated or the foil was poorly burnished.
- Cracks in the glass. Heating one side too much too quickly. Work evenly, and keep the iron on metal, not glass.
Read the workshop safety page before soldering for the first time. Keep the iron below about 430 degrees Celsius, because at that temperature the smoke is mostly flux, not lead.
In this section
- Glass Tools and Equipment
- How to Cut Glass
- How to Grind Glass and Apply Copper Foil
- How to Solder
- How to Make a Leaded Panel
- How to Cut Lead Came
- Working Safely With Glass
Terms used here are explained in the Glass Glossary, and the Learn section covers the history and types of glass.