What gilding actually is
Gilding is the application of metal leaf to a prepared surface. Genuine gold leaf is real gold beaten to roughly a tenth of a micron, thin enough that light passes through it and thin enough that it takes the shape of whatever is underneath. That second property is the whole discipline. The leaf hides nothing.
Almost every gilding failure a building owner sees is not a failure of the gold. It is a tool mark, a dust particle, a raised grain or a pinhole in the substrate, magnified by a reflective surface. The preparation is the job. The leaf is the last hour of it.
Genuine leaf against composition leaf
These are not two grades of the same material. They are different metals, and specifying the wrong one is the most expensive mistake available on a gilding scope.
| Genuine gold leaf | Composition leaf | |
|---|---|---|
| Material | Real gold, 22kt to 23.75kt | Brass and zinc alloy (Dutch metal, schlagmetal) |
| Tarnish | Does not oxidize. No clear coat needed. | Tarnishes in air. Must be sealed. |
| Exterior use | Yes, at 23kt and above | No. Fails in weather even when sealed. |
| Service life | Decades on exterior oil gilding | Often a few years |
| Material cost | High | A fraction of genuine |
The purity rule for exterior work. Gold does not corrode. The alloying metals do. Below roughly 23kt the silver and copper content is high enough that weather and pollution can discolor the leaf, which is why 23kt and 23.75kt are the standard exterior specifications for domes, statuary and architectural ornament. 18kt and 16kt are interior materials.
Oil gilding and water gilding
Oil gilding
Leaf is laid onto an oil-based adhesive called size, at the point in its cure where it has gone from wet to a specific degree of tack. Miss that window and the leaf will not hold or will not lie flat. Oil gilding gives a soft satin lustre, cannot be burnished, and is the durable method used for effectively all exterior work.
Water gilding
Leaf is laid onto a wetted clay bole over gesso, then burnished with an agate stone to a mirror finish that oil gilding cannot reach. It is water-sensitive, and it belongs on protected interior ornament, frames and altar work. On the same element you will sometimes see both, burnished highlights against matte ground, which is a deliberate contrast and not an inconsistency.
Where it shows up on a building
- Interior ornament. Moldings, cornices, capitals, ornamental plaster, carved millwork, ceiling detail and medallions.
- Exterior architectural elements. Spires, finials, domes, cupolas, railings, lettering and dedication plaques.
- Statuary and sculptural ornament. Exterior figures and detail, where genuine high-karat leaf and substrate preparation determine whether the work lasts a generation or a season.
- Historic restoration. Theatres, courthouses, banking halls and civic interiors where existing gilded ornament has to be matched rather than replaced.
- Glass gilding. Leaf applied to the reverse face of glass for signage and dedication panels.
- Reguilding. Existing gilded elements on institutional maintenance cycles, assessed element by element rather than patched indiscriminately.
Repair, or reguild the whole element?
Localized reguilding is possible and is routine on maintenance cycles. But new leaf beside aged leaf reads different in colour and lustre until it weathers in, and on a visible elevation that difference is what everyone will look at. Patching is right for damage that is isolated, low, or out of sightline. On a prominent ornamental run it is usually better and often cheaper over the cycle to reguild the element complete.
Why this is a short list of contractors
Gilding is not a scaled trade. It is slow, it is done by hand, the material is priced like the commodity it is, and the skill takes years on real buildings to develop because there is no forgiving version of it to practice on. Most painting contractors do not carry it, and most who claim it are quoting composition leaf.
The Paper Boys have performed gilding on ecclesiastical and institutional buildings since the 1990s, alongside wallcovering and specialty finish work. It is a line we have run continuously rather than picked up for a single project.
On working in occupied and operating buildings. Access windows, protection of adjacent finishes, dust control and off-hours scheduling are not administrative details on this kind of work, they are the schedule. Gilding cannot be rushed back into a tack window that has closed, and it cannot be done next to active dust. A contractor who has not worked this way tends to discover that on site, which is the wrong place to discover it.
Getting a number
Send the drawings, the finish schedule and the ornamental detail, along with photographs of any existing gilded work. For reguilding, the assessment of what is actually under the old leaf drives the number more than the square footage does, so a walk is worth more than a takeoff. Lump sum with a scope letter, alternates priced separately.