A deep flat, mottled black surface, blackened aluminum is a material which has use in limited architectural applications, and may be attractive for those seeking a unique appearance within certain parameters.
BLACKENED ALUMINUM APPEARANCE
The surface has a rough leathery texture with a flat, black sheen. The surface appears different when viewed from different angles. The finish obtained is not unlike a photographic negative of a smooth concrete surface with all the subtle variations that give concrete its unique attributes. Blackened aluminum appears mottled flat black with streaks of occasional whitish deposits.
The black color obtained is flat and mottled due to the variable coarse nature of the aluminum surface achieved. The roughened surface should be sealed with a clear coating to resist ultraviolet light and protect from heat absorption.
Like all black surfaces, particularly coarse, grainy facades, deposits of dirt and other substances contrast against the dark background. Rain does not aid in the cleaning of such shells because of the considerable roughness. Evaporation patterns develop on black coarse surfaces, leaving behind irregular deposits that can be difficult to clean, particularly if they have been left on for long periods of time.
Black is a great absorber of the infrared wavelength. It does not take long for a blackened surface to reach temperatures that are painful to the touch. Using blackened aluminum of this form requires recognition of the thermal characteristics the aluminum will undergo, as well as accessibility to the public.
Like all aluminum surfaces, blackened aluminum does not do well in pedestrian environments because it can be easily scratched. Stainless steel or a patinated zinc, copper, or steel whose patina will self-heal is a preferred option for designers seeking a material in an area with regular traffic.
ALTERNATIVES TO BLACKENED ALUMINUM
Alternatives to blackened aluminum include Solanum Steel, a weathering steel product by Zahner which is preweathered to an insoluble state and can be deepened to an indigo tone; Interference Stainless Steel, a stainless steel alloy with a durable protective coating; and Blackened Copper, a warm dark mineralized patina on copper. Blackened Steel is also an option for a similarly-toned surface, but it is not as enduring as the above options.