Coloured-glass technology has been revolutionised in the past 20 years. Leaded glass, the traditional coloured-glass manufacturing technique, remained unchanged from the days of the stained-glass Gothic cathedrals to the early 1990s. Because leaded glass had nothing in common with the large expanses of glazing dominant in 20th-century architecture, coloured glass was not popular with modern architects, despite a brief vogue with Mackintosh and Wright. But in the past 15 years, techniques have evolved that offer infinite possibilities for the use of coloured glass in buildings.
There are three main ways to apply colour to glass: firing enamels onto the surface of the glass (fritted glass); adding pigment to the interlayer of laminated glass; and applying coloured film to glass.
ENAMELS ON GLASS The term fritted glass evokes images of endless white dots, yet this is a very limited view of what can be done with fritting, as the dot can just as easily be black, blue, green or pink. Dots can also be arranged to create a photograph or design. The options are endless and dramatic effects can be simply achieved. The vocabulary of architecture is about repetition and rhythm, and the medium of printed enamels is perfectly designed to exploit this application.
Herzog & de Meuron pioneered the use of images on glass. At its Ricola warehouse (1993), a leaf pattern was repeated on the exterior fabric. At its Eberswalde School Library (1999), strips of photographic images were repeated across the facade, reading differently at a distance and close range. The cladding of the Cottbus Media Centre, near Brandenburg (2004), was covered in huge letters made up of white dots. Each image was printed over 100 times from a basic grid design of 25 panels.
At Innsbruck Town Hall (2002), Dominique Perrault and artist Peter Vogler transformed a five-storey glass stairwell with black dots printed on transparent glass, retaining a view of the cityscape beyond. Stairwells are appropriate for printed glazing because it adds interest to a transient space. The brilliance of Peter Vogler's design lies in the subtle use of repetition. Only four images are used on 60 glass panels. When screen-printing enamels, like all printing processes, the costs fall as images are repeated. The costs fall greatly in the first 10 panels, but the curve attens soon after.
The arresting exterior of Hamburg's Law Library (2004) by Medium Architects shows how simply a building can be made into a night-time landmark using coloured glass. The library seems warm and inviting, although one suspects it is full of terminally dull books. From the inside, a beautiful effect is achieved by this simple intervention, which creates a sort of modesty screen - with the printed etch lines adding to the rhythms of the design.
PIGMENTED LAMINATION Pigmented laminated glass uses a coloured layer as the laminate.
It has been possible to add pigment to poured laminate for some years now, but a new, more mechanised process which has been developed means that it is now becoming widely used. A large range of colours can be used in opaque or transparent form.
Two of the best known examples of pigmented lamination in the UK are the Home Office Building by Terry Farrell Partnership (2005) with artist Liam Gillick, and David Adjaye's Idea Stores.
The MUSAC building in Leon, Spain (2005) by Mansilla + Tuñón, uses coloured panels as opaque cladding.
FILM ON GLASS Coloured and digitally printed film must be used with caution because of its vulnerability and potential impermanence, yet this can be part of the attraction where change is a constant pressure.
Adhesive film does not easily peel off, taking considerable effort to remove. But it is not yet known how well it performs when exposed to sunlight for long periods. UV light can easily be screened out, but other parts of the light spectrum may have an impact on the durability of pigments; this has not yet been properly researched.
Dichroic films are transparent films that show one colour when transmitting light and a different colour when reflecting light. The colours mix to create many hues when viewed from oblique angles, creating otherworldly effects. Two projects showing the dramatic visual effects of these films are Niall McLaughlin's Silvertown housing for the Peabody Trust (2004) and UN Studio's La Defense Office Building in Almere, the Netherlands (2004).
CONCLUSION For large volumes of glazing where each panel is a single colour, pigmented laminated glass is an excellent technique, with the option of transparent, translucent and opaque panels. For projects where more than one colour, images, or gradations of colour are required, enamels offer a perfect solution. They can also be transparent, translucent or opaque, are permanent and include the added quality of surface texture. The low cost and enormous versatility of digital film make it an excellent option for internal interventions; because it is applied after the glass installation, film is a very low-stress option that can be included at a very late stage.
I have observed that people who pay for buildings, and seem to resent every unnecessary expenditure, are human enough to find that the millions spent on foundations, carpets, airconditioning etc. is not very exciting, while money spent on visible parts of the building provides a buzz long after completion.
The use of colour and images on glass merges art and architecture. No one has really explored what can be achieved with 'ornamentation' on glass. Instead of moulded stone, we could have printed patterns on glass running laterally or vertically, establishing the building's rhythms and form. Incorporating art into architecture involves more thought, discussion and uncertainty than almost any other component. It is time-consuming for architect, client and probably contractor. Yet if well integrated, it can give a building definition, strength, beauty and colour.