Stained & Leaded Glass
Stained Glass & Leaded Window Restoration
Releading, panel stabilisation, bowing correction, protective glazing and dalle de verre — for churches, brownstones and landmark buildings across New York City. Documented, disassembled and rebuilt by hand in our Newark workshop.
What fails in a leaded panel
A leaded panel is a structure, not a picture. Individual pieces of glass are held in channels of lead came, the joints are soldered, the whole assembly is cemented to make it rigid and weathertight, and the panel is then supported by saddle bars tied back to the frame. Every one of those elements has a service life, and they do not fail at the same rate.
- Lead fatigue. Came work-hardens and embrittles over decades of thermal cycling and wind loading. Once it has gone brittle it cracks at the heart of the section, and no amount of surface repair restores its strength.
- Bowing and bulging. The classic symptom. A panel that has lost its rigidity deflects under its own weight and wind pressure, first into a gentle belly, then into an S-curve. Left alone it fails progressively — bowing puts the glass in bending, and glass does not bend.
- Failed cement. The waterproofing compound between came and glass dries out, powders and falls away, so the panel loses both stiffness and its seal, and water starts moving through it.
- Cracked and lost glass. Impact, stress from a bowing panel, and old repairs done in silicone or copper foil that have simply been laid over the problem.
- Broken solder joints. Every joint is a small structural connection; a run of failed joints turns a rigid panel into a loose net.
- Corroded or missing saddle bars. The bars carry the panel. When they rust through or were removed during an earlier "repair", the panel is left carrying itself.
- Failed perimeter and frame. On a stone or wood surround, a failed perimeter seal delivers water straight into the head of the panel.
A panel that is bowing, rattling or shedding cement is not stable, and it is worth saying plainly: the cheapest moment to deal with a leaded window is before the glass starts breaking, not after.
Documentation and rubbings before disassembly
Nothing comes apart until the panel has been recorded, because once the came is cut the original layout exists only in the record you made of it.
Each panel is photographed in situ and then on the bench, front and back, raking light and transmitted light, with close-ups of every unique detail, every earlier repair and every painted or stained piece. Condition is mapped: cracks, losses, previous interventions, areas of paint loss.
Then a rubbing is taken — a full-size record of the lead lines pressed off the panel itself. That rubbing becomes the template the panel is rebuilt on, so the geometry of the finished window is derived from the original object rather than from a redrawing of it. Numbering keys every piece of glass to its position on the template before a single joint is opened.
This is also the documentation Landmarks expects for special windows. Stained glass falls into LPC’s "special windows" category, which has to match on all five attributes — material, operation, configuration, details and finish — on every facade whether visible from the street or not, and needs a condition assessment as part of the application.
Releading in the workshop
Full releading is the definitive repair for a fatigued panel, and it is the only one that restores the panel’s structure rather than delaying its collapse.
The panel is unsoldered and dismantled over the rubbing. Every piece of glass is cleaned of old cement by hand and checked. Cracked pieces are edge-bonded or, where the break is unstable, supported with a fine repair lead; pieces that are lost are replaced with glass matched for colour, texture and — critically — period, because the character of nineteenth-century glass comes from how it was made. Painted and stained pieces are conserved, never repainted over.
The panel is then rebuilt on the template in new lead came matched to the profile and width of the original, so the drawing of the window does not change. Every joint is soldered front and back. The rebuilt panel is cemented, cleaned, and left to cure, and new saddle bars are fitted and tied in so the finished panel is carried properly instead of carrying itself.
Where a panel is sound but locally damaged, full releading is not the answer and we do not propose it — targeted repairs, edge-bonding and localised came replacement keep more original material on the building.
Dalle de verre
Dalle de verre — faceted slab glass, set in a matrix of reinforced concrete or epoxy resin — is mid-century work, largely liturgical, and it is the one glazing type in New York that almost nobody still services. We do.
It fails differently from leaded glass because the problem is usually the matrix rather than the glass. Concrete matrices carbonate, crack and spall, and the internal reinforcement rusts and expands, splitting the panel from inside. Epoxy matrices chalk, yellow and embrittle under UV. Individual dalles work loose, and the joint between panel and surround opens up.
Restoration means stabilising or rebuilding the matrix, re-setting loose dalles in their original positions, replacing lost slabs with glass matched in colour and thickness, and dealing with the reinforcement rather than skinning over it. These are bold, uncompromising modern works, and they are steadily being lost to buildings that assume they cannot be repaired.
Protective glazing
Protective glazing is a secondary sheet of glass or glazing set outboard of a historic panel, and used properly it is the single most effective thing you can do to extend the life of restored stained glass — it takes the wind load, the impact risk and the weather off a panel that was never designed for another century of it.
Used badly it destroys the window. The failure mode is trapped moisture: seal the historic panel tightly behind a sheet of glass with no ventilation and you build a condensation chamber against the glass and the came, which accelerates exactly the deterioration you were trying to prevent. Correctly detailed protective glazing is ventilated, so the cavity breathes and moisture cannot accumulate.
It is also a visible change to the exterior of the building, so on a designated property it is part of the Landmarks application, not a detail to be settled on site. Landmarks has explicit criteria for storm windows and added glazing at primary and visible secondary facades: fitted tightly within the opening with no added panning, set as far back from the exterior wall plane as possible, framed in wood, metal or fibreglass painted to match the primary frame colour, glazed clear, and echoing any mullion or meeting-rail pattern in the window behind. For special windows such as stained glass, the glazing must be clear — not tinted.
Reinstallation
A restored panel is only as secure as what carries it. Reinstallation starts with the opening: the frame, the rebate and the perimeter are made sound first, because refitting conserved glass into a failed surround wastes the work.
Panels go back in their recorded positions and orientations, bedded and pointed so the perimeter is weathertight, with saddle bars tied back into the frame to carry the panel and any ferramenta cleaned and treated rather than replaced by default. Where protective glazing forms part of the scope it is fitted with its ventilation path deliberately detailed and left open.
Finally the work is documented — photographs of the completed installation, the record of what was done to each panel, and the closeout material Landmarks needs to confirm the finished work matches the approved application.
Common Questions
Questions we get asked on this work
My leaded window is bowing outward. Is that urgent?
It needs attention, yes. Bowing means the panel has lost its rigidity and is deflecting under its own weight and wind pressure, which puts the glass into bending — and glass does not bend. Left alone the deflection increases and pieces begin to crack, so the work moves from releading a complete panel to releading a panel with losses that have to be matched. Getting it assessed while the glass is still intact is materially better.
Do you have to take the whole window apart to fix it?
Not always, and we do not propose it when it is not needed. Full releading is the right repair when the came has become brittle through fatigue, because that is a whole-panel condition. Where a panel is still sound but locally damaged, targeted repairs, edge-bonding of cracked pieces and localised came replacement keep more original material on the building.
Can you match glass in a nineteenth-century window?
Yes, and matching period as well as colour matters. The character of historic glass comes from how it was made, so a modern sheet in the right colour still reads as wrong. Pieces are matched for colour, texture and period, and painted or stained pieces are conserved rather than repainted.
Is protective glazing a good idea?
It is, provided it is ventilated. Protective glazing takes wind load, impact risk and weather off a panel that was never designed for another century of exposure. Sealed tight with no ventilation path, though, it traps condensation against the historic glass and came and accelerates the deterioration it was meant to prevent. On a designated building it is also a visible exterior change, so it forms part of the Landmarks application.
Do you work on church windows as well as houses?
Yes. Churches and institutional buildings are a significant part of the leaded and stained glass work, along with brownstone transoms and stair-hall windows — and dalle de verre, which is almost entirely liturgical, is a discipline we keep in-house.
Free Assessment
Get a free on-site assessment.
We visit your building, inspect the windows one by one, discuss any board or Landmarks requirements, and walk you through the options — restoration, replacement and approvals. No cost, no obligation.