Treating a Sculptural Staircase to a Controlled Bronze Patina
Project: Knightsbridge, London
Commissioned by: The Stonemasonry Company and ARTISTEEL
Architects: Undercover Architecture
Finish: Bespoke bronze patina with sealed lacquer sheen, waterborne system
Photography: In-progress and final images as shown
The challenge
Undercover Architecture designed an extraordinary spiral stair whose limestone treads sweep through the room like a whale’s backbone. Running alongside that stone structure are two monumental bronze “ribbons” forming the balustrade. ARTISTEEL delivered the metalwork and The Stonemasonry Company crafted the porous limestone. Both teams faced the same question that brought us in: how do you achieve a perfectly even patina across metres and metres of curved bronze, from the upper landing down to the last tread, and then lock it in so it stays beautiful without dulling the metal beneath?
That is exactly the kind of problem our studio exists to solve. Our work is about control. We create finishes that are repeatable across complex geometry and remain stable over time. The request here was a deep, refined bronze that felt natural, not a patchy or over-aged effect. The surface had to look like a true metal patination while reading consistently in every view and under every lamp in this double-height space.
Why control matters with real bronze
Traditional bronze patination is reactive. It relies on acids, oxides and the atmosphere to develop colour. On a staircase ribbon that twists, rises and catches light differently at every point, reaction rates vary. One zone can leap darker, another may stall, and the result can be blotchy. Add London’s dry or humid days into the mix and the risk multiplies. We were asked to bring the finish back under the hand of the craftsperson so the client, the architect and the metalworker could all know precisely what they would receive.
Our waterborne lacquer glaze solution
We proposed sealing the bronze and then building a patina with our waterborne lacquer glaze tinted with Mixol universal tints and fine metallics. This method gives us the tonal depth of a classic patina while letting us control the density, transparency and undertone. The steps:
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Survey and protection – The limestone is exquisitely porous, so first we protected every tread, riser and floor junction. Our site protection is second to none and was critical in such a pristine interior.
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Bronze preparation – Careful degrease and key to ensure the seal coat bonds without changing the metal’s character.
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Test panels – We always test. Craft is not a science. Even when you know a system will work, the correct approach is to verify on the exact substrate. We created a dedicated sample for sign-off.
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Seal coat – A clear, waterborne foundation that fixes the metal’s surface so no further oxidation can roam across the ribbon while we work.
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Patina glaze – Multiple ultra-controlled passes of lacquer glaze with Mixol tints and discreet metallics. The aim was a deep, even bronze that still read as metal.
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Final sealing to the correct sheen – Perhaps the most important step. We tuned the topcoat so the sheen matched the natural reflectance of bronze rather than looking “varnished.” The eye reads it as real metal because the sheen is correct.
Everything in our Advanced Lacquer Paint System is water based or waterborne, quick curing and low odour. We control dust with extraction at source and keep the workspace orderly for the design team, our crew and the environment.
A patina that will not drift
Because the bronze was sealed before patination, the colour you see is the colour that remains. There is no hidden reaction continuing under the surface. The staircase will not creep from bright to blotchy or from warm to green over the seasons. The patina is designed, applied and locked to stay looking this good.
The result
From the top landing to the final step, the bronze ribbons read as a single, continuous gesture. The tone is rich, the transitions are unbroken, and the sheen echoes the underlying metal. In the morning light it glows softly; under evening pendants it carries a dignified depth. The limestone treads by The Stonemasonry Company appear even creamier by contrast, and the entire composition holds together as one sculptural form.
Our wider metal and leaf patina experience
This approach is the same principle we use on metal leaf ceilings. We rarely use real silver, as it tarnishes unpredictably. Instead we apply aluminium leaf, seal it, then glaze with warm champagne or sienna tones, sometimes easing towards burnt umber in the corners. Again, the key is control: the colour is designed, tested and fixed. Clients get the glow they want without later surprises.
We also bring this precision mindset to smaller details. A good example is Hand painted marble socket plates that disappear into a stone wall or a faux-marble column. When the background is highly figured, those little plates can jar. Our team paints them to match the veining and ground colour so the eye reads a complete, calm surface. The same eye for tone, sheen and edge control that makes a staircase succeed also makes accessories vanish elegantly.
Process discipline on site
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Protection first – We wrapped, masked and boarded every surface before we ever lifted a brush.
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Clean air – Sanding and extraction were managed so dust did not drift through this large open plan space.
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Documented stages – Agreed checkpoints allowed the design team to review the patina density before the final seal.
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Waterborne throughout – All coats came from our Advanced Lacquer Paint System, keeping the site comfortable and the programme efficient.
Working with specialist partners
Projects like this only succeed when every specialist respects the others’ craft. ARTISTEEL’s fabrication quality gave us an immaculate canvas. The Stonemasonry Company’s limestone set the tone for softness and refinement. Undercover Architecture created the narrative thread that holds the whole interior together. Our role was to tune the surface so light, metal and stone speak in the same language.
What did we do on this staircase?
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Sealed raw bronze ribbons to stop uncontrolled oxidation.
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Applied a controlled waterborne lacquer glaze patina using Mixol tints and fine metallics.
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Finished with a calibrated topcoat to match true bronze sheen.
Why not a reactive chemical patina?
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Reactive finishes can vary with humidity, temperature and geometry.
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On long, twisting surfaces they often turn patchy.
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Our lacquer glaze system keeps the look consistent, reviewable and repeatable.
Will the colour change over time?
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No. Because the metal is sealed first, there is no continuing reaction under the glaze.
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The final topcoat locks sheen and colour so it remains stable.
Can you match other metals or tones?
Yes. We can tune from bright antique brass through deep oil-rubbed bronze. The same control applies to architectural metalwork, furniture and even small accessories such as Hand painted marble socket plates or metal trims around stone.
Is it sustainable?
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All coatings used are water based or waterborne.
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Low odour and fast drying reduce site impact.
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Long-term stability means fewer reworks and a lower lifecycle footprint.
Typical applications
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Feature stair balustrades and handrails
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Architectural screens and door sets
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Leafed ceilings and coves using sealed aluminium with champagne or sienna toning
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Joinery hardware, trims and Hand painted marble socket plates for visual calm
Key takeaways for specifiers
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Choose controlled, waterborne patina systems when you need consistency over large or complex forms.
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Always agree sheen levels against the natural metal you wish to emulate.
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Protect porous materials thoroughly before any bronze work begins.
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Require a signed sample first. Craft is predictable when it is tested.
Ready to discuss your project?
If you are planning an architectural stair, a metal screen or a room where stone and metal need to sing together, we can help you define the right surface language and deliver it cleanly on site. Explore more finishes at Specialist Decoration London and contact us to book a sample session or site visit:
www.specialistdecorationlondon.co.uk – “Treating this beautiful staircase to a bronze patina design and one of our bespoke lacquer finishes. Commissioned by @stonemasonry_comp_stonestair and @undercoverarchitecture.”
