Roofs from Melbourne to Malaysia are turning green and blue as a result of a collaborative project involving the University of Queensland and industry partners.
The project, which aims to improve the architectural use of copper as a roofing material, is capitalising on the aesthetic appeal of the green patina which can occur naturally as copper roofing ages.
The project is now at the commercialisation stage. Researchers have studied a model of this natural process and produced an artificial pre-patination process which gives the appearance of a natural patina. It is hoped ongoing research will result in an artificial patina, which is supplanted by the real thing as the copper ages.
Stunning architectural examples of the new product, known as Copper Heritage Patina, include Clairmont, a prestigious architectural building with an 800 sq metres patinated green and brown copper mansard roof in Toorak, Melbourne; and the Bank Negara Disaster Recovery Centre, Malaysia, which features 800 sq metres of lighter blue pre-patinated copper panelling.
Both projects were completed to architects' color specifications, and other large prestige projects in Vietnam and Brunei are in the pipeline.
The new product, which can be applied on-site to client specification, has resulted from a six-year Australian Research Council collaborative research grant-funded project.
Industry partner for the first four years of the project was Copper Refineries Pty Ltd (an MIM division). Current industry partner is Brisbane copper roofing specialist Copperform Pty Ltd. The University's technology transfer company, UniQuest Limited, is facilitating access to the technology.
The study is headed by Associate Professor Andrejs Atrens of the University's Mining, Minerals and Materials Engineering Department, who has an international reputation in studying mechanisms of copper corrosion.
Dr Atrens, who established the University's Corrosion Laboratory, has developed corrosion-resistant materials and undertaken major work for the International Copper Research Association on the corrosion mechanism in copper radiators.
The project arose because industry partners were seeking to increase their product ranges and were examining why copper roofing - once important historically - was now rarely used. Copper roofs were once popular with artisans because copper is malleable and easy to work, while it is resistant to corrosion once a patina is formed. Many European copper roofs are several centuries old.
Research indicated production and labour costs were large factors in consumer decisions, so manufacturers developed processes to shave costs while still producing high quality materials for a niche prestige market.
Dr Atrens said researchers on the patination project first had to understand how the natural process worked, before tackling the acceleration of the process, which proved to be 'extraordinarily' difficult.
'Patination occurs during the presence of a water layer on the surface, and in the natural course of events, this occurs during a small fraction of time,' he said.
The researchers developed a patina compound which can be applied to the copper surface layer, corresponding to the natural porous layer on copper known as bronchantite. Although research is still continuing, the compound, which gives the appearance of a natural patina, is designed to react in time with the natural cuprite layer beneath and ultimately be converted to a completely natural patina.
Two varieties of pre-patination have been developed - a green, corresponding to the natural process typical in very old copper-roofed European buildings, and a tailored version in a lighter blue color, proving popular in south-east Asia, where there is no historical tradition of copper roofing.
Dr Atrens said the University of Queensland researchers were tackling technical problems as they arose to ensure that surfaces were prepared to exact standards, that the process was applied correctly, and color was consistent and correct.
'The other side to understanding the process is that our industry partners and their clients can have comfort in the warranty,' Dr Atrens said.
He said the process was increasing the popularity of copper roofing, and represented a potentially important domestic and export market activity for Australia.
Copperform Pty Ltd general manager Dallas Mulholland said the export market for the patinated copper was 'potentially huge', especially in Asia.
While the Asian market was not familiar with copper and its ageing process, accelerated by airborne pollutants, it was very interested in the aged look of materials but wanted it 'straight away', he said.
Mr Mulholland said copper roofs were expensive but some private buyers in the Asian market had homes 'which justify the cost of a copper roof'.
Generally however, copper was used for government and commercial buildings which would stand the test of time.
Mr Mulholland said while the University had carried out the research process Copperform Pty Ltd had been working on building its copper market.
'It is now up to us to develop a market for the patinated process and while it is still in its infancy, there is no doubt demand will develop over the next few years,' he said.
Mr Mulholland said current projects included the copper roofing of buildings in Brunei and Vietnam, while projects were being quoted in Singapore and other parts of Asia.
Researchers involved in the project also included Departmental adjunct research associate Dr Jason Nairn, postdoctoral research fellow Dr Ayo Olofinjana, and PhD student Grant Skenerton. Dr Ken Fitzgerald was awarded a PhD for a study to develop the basic patination model.
For further information, contact Dr Atrens, telephone 07 3365 3748 or Mr Mulholland, telephone 07 3273 7999.
