Patina

The only kind of ageing worth waiting for.

Metal that transforms in the air and gets better rather than worse. What takes decades outdoors is created here under controlled conditions.

What patina really is

The core

Not a layer on the metal, but the metal itself

Paint, powder and film lie on a material. They have an edge against the substrate, they can flake off, and under a scratch something foreign appears. Patina works differently. It forms when the metal itself reacts with the air and converts at the surface into its own compounds.

On copper these are mainly basic carbonates and sulphates, with chlorides added near the coast. The layer sits firmly, is stable in itself and renews where it has been damaged. It slows down further attack by air and moisture instead of accelerating it.

OriginOut of the material itself, not applied.

AdhesionFirmly bonded, no flaking, nothing to scrape off.

EffectProtects the metal underneath from further attack.

When damagedThe layer keeps working and evens out over time.

Figures on composition and protective effect according to information print i.30 of the German Copper Institute.

Five materials

Not every metal ages the same way

We finish copper, brass, bronze, stainless steel and weathering steel by patination, burnishing and oxidation. Each material brings its own colour range.

CopperThe classic. Bright red gold when new, chestnut brown over months, anthracite brown over years, and finally green on pitched roofs. Every intermediate stage can be reached and is aimed at deliberately. Copper patina in detail.

BrassAn alloy of copper and zinc. The zinc content shifts the colour range towards yellow, from gold red at low content to pale yellow at high. Burnished, the range runs from warm bronze brown to almost black. Burnished brass.

BronzeAlso a copper alloy, darker and quieter than brass. On buildings it appears as facade cladding and in interiors, for example at the Joseph Pschorr House in Munich and at the Mozarteum in Salzburg.

Stainless steelUnlike the copper materials, stainless steel forms no coloured layer of its own, it stays as it is. Its colour comes from the way it is worked. Four tones are available: Light, Dark, Light Brass and Dark Brass.

Weathering steelCorten steel forms a firmly adhering layer of rust and therefore follows the same principle: the material protects itself by transforming at the surface. The result is a warm rust brown.

The materials one by one

Three routes

Patination, burnishing, oxidation

Three processes, three colour worlds. Which one suits a project depends on the material and on the tone you are after.

Green and turquoise

Patination

The familiar state of an old copper roof. For copper, in weeks instead of decades.

Warm brown

Oxidation

The tones that lie on the way to green. From copper orange to almost anthracite.

Dark and deep

Burnishing

The process for brass. From warm bronze brown to nearly black.

How this works in the workshop

In depth

Where it goes into detail

The individual materials and processes have their own sites with sample surfaces, technical data and images of completed projects.

Copper greenColour worlds, ageing over the years, copper roofs and the difference to verdigris: patina-kupfer.de

Copper brownFour oxidised tones, wall cladding and facades: kupfer-oxidiert.de

BrassEight burnished tones, references and technical data: messing-brueniert.de

ProcessesKnowledge for planners, tender texts and data sheets: kupfer-patiniert.de

Frequently asked

What you should know about patina

What exactly is patina?

A layer that forms when a metal reacts with the air. On copper it consists mainly of basic carbonates and sulphates, with chlorides added near the coast. Unlike paint it does not sit on top of the metal, it is made of the metal itself, transformed. That is why it cannot peel and cannot be scraped off.

Is patina the same as rust?

No. Rust on iron keeps eating into the material and destroys it over time. The patina on copper and its alloys does the opposite: it adheres firmly, is stable in itself and slows down any further attack. It is the reason copper roofs survive for centuries.

Which metals develop a patina?

Copper is the best known, turning green over the years. Brass and bronze also change in the air, but differently: they darken towards brown and grey brown tones. We finish copper, brass, bronze, stainless steel and weathering steel by patination, burnishing and oxidation.

Why have patina produced in the workshop?

Because of time and because of evenness. Outdoors, copper needs eight to fifteen years to reach a strong green depending on its location, and nobody knows in advance how it will look in between. In the workshop the desired state is created beforehand and arrives finished on site. On large surfaces that is the only way to a uniform appearance.

What is the difference between patination, burnishing and oxidation?

They are three routes to three different colour worlds. Patination takes copper to green and turquoise. Oxidation stops at the warm brown tones that lie on the way there. Burnishing is the process for brass and leads to deep, dark tones from bronze brown to almost black.

Is patina toxic?

No. Patina on copper consists of basic copper compounds and irritates neither skin nor airways. It is often confused with verdigris, which is something else: copper acetate, formed by acetic acid and genuinely harmful. On a building verdigris practically never occurs.

Does patina look the same everywhere?

No. Its composition depends on the air at the location. Near the coast a blue green tone often forms, in a city it stays with dark brown for longer. The pitch and orientation of the surface play their part too, as does the amount of rain that actually reaches it.

Can a patinated surface be repaired later?

That depends on the case and cannot be answered in general. Small areas of damage often even out by themselves over time, because the layer keeps working. On visible surfaces with high demands we settle this on the project, before anything is manufactured.

Next step

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