Emerging technologies

With solid colours the norm and metallic effects continuing to grow in volume, what is next for construction cladding?

Pearlescence is an effect beginning to appear in pre-finished steels, although it has more typically been seen in automotive, domestic and consumer applications, rather than construction. This mother-of-pearl effect can vary in strength from subtle shimmers to dramatic colour changes, although the more extreme could be overwhelming on large expanses of cladding.

Pearlescent finishes use particles of mica integrated into the paint to both reflect and refract incident light, creating a complex appearance which shifts with the angle of lighting. These products will look one colour from a certain angle; yet from another will give a completely different colour. As with metallic pigments, the size of the mica particles, typically 10-25 µm affects the appearance and can be tailored to achieve the desired level of sparkle.    

Thermochromic pigments change appearance with temperature. Their use has been restricted to either scientific instruments such as thermometers, or novelty items and clothing which reveal patterns or prints when the temperature rises. Whether they could be incorporated into a pre-finished steel is unclear, but they could serve far more purpose than pure gimmickry. Altering colour through the day, the building skin could help to regulate the degree of solar gain, a so-called ‘self-thermostatting’ capability. The trick with this would be achieving a large colour change over a restricted temperature range, with a reasonable level of performance.

A whole plethora of other effects are available in other industries. Holographic finishes have been used on metal packaging, whilst complex sublimation printing finishes have also been imparted to pre-finished steels for billboards. Various textures, embosses and patterns have also been added to the basic coatings to enhance the appearance.

One area with more tangible benefits to architecture is that of self-cleaning coatings. Pollution, grime and atmospheric conditions will take their toll on even the most pristine of buildings with the original appearance deteriorating gradually. Self-cleaning glass is available and it may only be a short time before this is available in
pre-finished steel. This has obvious benefits for external cladding and could reduce maintenance and provide a clean building appearance over a longer period of time.