Richard Besant of Powdertech Corby discusses why powder coating on aluminium presents a convincing alternative for creating a wide variety of architectural features and designs
Recent advances in powder technology and application now mean that aluminium and steel can be powder coated as a credible alternative to natural elements such as stone, wood, terracotta, copper and bronze, and to the processes of anodising and Corten steel.
Finding a combination that will bring life to a piece of metal, making people admire it, touch it, and wonder whether it is ‘real’ wood or stone or bronze, is a delight for any architect or designer. Using aluminium, or steel in preference to scarcer materials is paramount in an era fully aware of the need to protect natural resources. It makes perfect sense to use aluminium for as many construction purposes as possible, including those regarded as decorative, which is where wood, stone, coppers and bronzes have often been the materials of choice. In most cases it is the appearance of these materials that is desired, rather than their inherent properties, and powder coatings can satisfy that aesthetic requirement. Light weight, strong and recyclable, aluminium can easily be made to resemble these earthy natural elements.
Aluminium is the most abundant metal in the Earth’s crust and iron follows closely behind with steel being an alloy of iron, carbon and other elements. Both metals are highly recyclable, with 75 per cent of aluminium in use today being recycled. Powder coating has no effect on the recyclability of aluminium or steel. It has clear environmental advantages over wet paints by being a dry powder, with no solvent, and therefore emitting no volatile organic compounds (VOCs). Powders contain no halogens or heavy metals and there is no hazardous waste. The coating process is a factory-controlled application-taking place in a sealed booth and excess powder is collected and re-used so waste is minimised. Many powder coatings have a reaction to fire classification of A2, S1-d0, making them suitable for construction.
An exceptional metal
It is little wonder that aluminium is the 21st century’s building material of choice. In addition to its abundance and high level of recyclability, aluminium is extracted, processed and fabricated with a high degree of efficiency. For architectural features, aluminium has some unequalled advantages over other materials. It is ductile and can therefore be formed into complex shapes and profiles whether extruded, folded, rolled, cast or machined. The products can be flat, curved, perforated, expanded or sandwiched with other materials. Aluminium is also lightweight and therefore easy to transport and easy to work with. It has an exceptional strength to weight ratio and can achieve long spans, leading to fewer fittings and faster installation. With excellent intrinsic corrosion resistance, aluminium does not become brittle at low temperatures; in fact it increases in tensile strength.
A clean finish
Stone or wood on a building looks attractive when clean, free from lichen, mildew and general staining. These materials need a rigorous maintenance routine to keep them looking at their best. Powder coatings, on the other hand, need minimal maintenance – a quick wash over with water and a basic detergent will remove and prevent staining. The natural appearance of rusted steel has been popularised by the product Corten, but the rusty surface still leeches colour and can stain surrounding materials. A powder coating emulating rusted steel will not leech colour.
Consistency within powder batches is a known benefit of powder coating especially for modular builds, allowing the colour to be consistent across the development. Where variation in shade and tone is needed, reflecting that found in natural materials, powder coating again meets this need to give a ‘consistent inconsistency’, achieving a realistic overall impression of homogeneousness. Powder coatings can impart many different appearances to aluminium, allowing architects and designers to introduce the appearance of stunning, natural materials into their projects without using less manageable materials.
Richard Besant is sales director at Powdertech Corby