Leaded Lights
Panels of glass cut to a cartoon and held in H-section lead came, soldered at the joints and cemented for weathertightness. Made to the measured opening, whether plain quarries or painted and fired glass.
Carbon and evidence
How This Is Made
An Environmental Product Declaration is issued by a manufacturer against a declared unit. This record has neither, so it states sourced facts about process and provenance instead of a carbon figure.
Continuous English tradition from the medieval period; the releading cycle is why so much early glass survives at all
Process
Feedstock
Glass
Float or mouth-blown sheet glass, both manufactured products, with extruded lead came sold by the length
Process heat
Furnace-melted
The glass is furnace-melted at roughly 1,400–1,600 °C, and painted glass is kiln-fired again to fix the pigment. This is the highest process temperature in the collection, and it sits in the bought-in sheet rather than in the studio.
Binder
Mechanical
Fabrication
Workshop-made
Sourcing: glass internationally sourced; the panel is made to the opening locally
Who Builds It
Specialist trade
Limited UK availability
Cut to a full-size cartoon drawn for the specific opening. A change to the opening after the cartoon is drawn is a remake, not an adjustment
End Of Life
Separable
Releadable — the panel is taken apart, the glass cleaned and re-cemented into new came, repeatedly over centuries
Maintenance: Releaded roughly every 100–150 years depending on exposure; individual quarries replaced without disturbing the rest
Specification Risk
What a specifier has to resolve before this can be built.
- Certification
- No BS EN 1279 sealed-unit performance, no U-value and no CE mark. A single-glazed leaded light will not meet Part L on its own
- Fire
- Non-combustible glass, but no fire rating is held for the assembly
- Warranty
- Studio workmanship warranty
- Insurance
- Security and impact resistance are poor without secondary or protective glazing — check the exposure
- Supply
- A small number of studios; conservation work books out well ahead
Read This Honestly
- •The glass is furnace-melted at around 1,500 °C and painted work is fired again. Nothing about hand-glazing reduces that.
- •Lead is a controlled material for handling and disposal, however inert the finished panel.
- •Single glazing. Meeting Part L normally means secondary glazing or a protective glazing screen, which changes the appearance and the cost.
Design & Specification Notes
Panels of glass cut to a cartoon and held in H-section lead came, soldered at the joints and cemented for weathertightness.
Material Note
The glass is a manufactured sheet and the came is extruded and sold by the length. What is made to order is the panel: cut to a cartoon for one opening, at one size, and not repeatable from a catalogue.
Typical Uses
- •Glazing systems
- •Daylight openings
- •Thermal envelope
Key Performance
Supports daylight and thermal performance of the envelope.
Specification Actions
- •Ask the studio which glass is specified — mouth-blown restoration glass and float glass are different products with different declarations.
- •Confirm how the panel is protected and supported: unrestrained leaded lights bow over time, and saddle bars or a protective glazing screen are a design decision, not an afterthought.
- •Leaded lights are releadable — the glass is recovered and re-cemented into new came, which is why medieval glass survives.
Indicative Health & Indoor Air
- •Lead came handling
- •Lead-bearing cement
Lead came and its cement are a handling and disposal control for the studio and for anyone stripping an old panel. Inert once installed and cemented.
Products in this category
6 products from 3 manufacturers · 17 in this category. Ordered by the evidence each record holds, never by commercial standing.
Specification
- Finish
- Glass quarries in lead came, cemented
- Service life
- 100 years