Their proposal of a fully glazed, transparent, elegantly decorated façade by way of outside cladding won Foreign Office Architects (FOA) the commission for the John Lewis Department Store at Leicester, England. The double curtain wall is of structural glass decorated by the “ipachrome design” technique invented by Interpane. The effect is thus both ornamental and functional, since the spray process for applying the decoration gives effective protection against inquisitive eyes and sunrays, transmittance being a mere 4%. The lace-like coating is back-lit by night in a range of 256 colours. Structural glass gives the façade an especially harmonious appearance, as well as some practical advantages: for example, rainwater washes off all traces of dirt. In all, the glazed surface is 5,000 sq m. made up of 625 panes each measuring 2.4x5.4 m. The pattern helps disguise the joins and give the impression of one piece. For the outside the multilayer system designed by ipachrome has the look of a brightly reflecting, silver-backed mirror. Unlike other reflecting surface cladding, it is highly resistant to damp and humidity.