Fan Lee of Anometal, describes a coating-free anodised aluminium that cleans itself, photocatalysis to break down the organic dirt, and a super-hydrophilic surface (a water contact angle of 8.9°) to let rain wash it away. Formed inorganically with the aluminium-oxide layer, it is rated to stay clean for over 25 years.
The finish is branded PuraMax, or ‘Solar Forever’. Anometal, a Shanghai chemical company founded in the mid-1990s, pioneered continuous coil anodising in Asia and now runs three lines; the pitch here was a coating-free surface that keeps a façade clean for decades. The problem it answers is familiar: modern façades are increasingly curved and complex, hard to reach, and painted panels streak with ‘sagging stains’ from sealant oils, washable for a decade or so, then not at all.
The science is two effects layered together. Photocatalysis, discovered in 1972 by two Japanese scientists, uses the UV in daylight to break down the organic matter that makes dirt stick, which also gives it antibacterial and anti-mould properties. And super-hydrophilicity: the surface holds a water contact angle of just 8.9 degrees, so rain sheets across it and carries the loosened dust away rather than beading up.
What Anometal claims as its own is doing this inorganically. Others have mixed titanium dioxide into paints, PVDF, PVF, PE, but photocatalysis is indiscriminate: it eats the paint as readily as the dirt, so the coating powders away in a few years. Japan solved it with fired ceramic tiles that have kept buildings clean for thirty years; Anometal’s move was to grow the titanium-oxide crystal together with the aluminium-oxide layer, a ‘rocky road’ of the two, as a purely inorganic self-cleaning oxide, formed at room temperature on an aluminium that melts at 660 degrees.
The result, Lee said, is a self-cleaning oxide rated to last 25 years and, he believes, potentially 50, a ‘lifetime maintenance-free’ façade. Third-party testing backed both effects: a red-inked sample turning silver under 24 hours of UV, a colour shift far past the standard threshold; and the 8.9-degree water contact angle for the hydrophilic side.
The other half of the talk was colour. Anometal claims to be the only maker of a UV-stable grey outdoor anodised finish, alongside warm bronze, copper and brass. Lee ran through projects across Australia and Asia, Monash University and work in Sydney, plus large cultural and stadium façades in China, arguing that pre-anodised aluminium can carry both the look and the low-maintenance longevity that a complex façade needs.