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www.engineeringnews.co.nz 29 environment in which it is displayed,” he adds Boulton says he has been involved in a variety of public art conservation projects in New Zealand. “Unfortunately, very few conservators have a metallurgical or scientific background,” he says. “They may be experts in art or history but can fail to follow appropriate engineering procedures, especially when dealing with large kinetic sculptures (wind sculptures)” One issue that is often ignored is the prospect of litigation if the structure of a public artwork fails and causes damage or injury to the public. There are an increasing number of large public artworks that have moving components and it is these joints and bearings that are often the weakest point and which pose a threat to public safety in the event of a failure occurring. Information about the effects and impact of corrosion on public art should be widely disseminated. “Very little has been written about this topic as we could find no papers in the public domain dealing with the issue,” Mr Boulton says. He adds that his co-author on the paper he presented at C&P2015 once told him that the word “corrosion” wasn’t even mentioned in art conservation training. One of the most common types of damage that is done to public art and infrastructure is graffiti. Some modern artworks include expanses of flat metal that attract vandals. Justin Rigby, coatings consultant at Remedy Asset Protection, said that there are various types of coating that can be used depending on the type of art and the material it is made from. Coatings are mostly classified as either sacrificial or non-sacrificial. Sacrificial types are coatings which can be removed during cleaning to take away surface layers thus removing graffiti. Such a process can usually be repeated several times before a complete new coating needs to be applied. Examples are wax based coatings. Non-sacrificial coatings are extremely hardened materials that are much stronger than the harsh solvents that are used to dissolve and wash off the paint or ink used by vandals. The performance of the coating is only affected after many cycles of graffiti removal. Mr Rigby says that some of the latest research involved nano coatings. “Most surfaces are porous at the microscopic level so graffiti can leach relatively deeply into a surface layer,” he adds. “The material of a nano coating fills in all the tiny holes to create an essentially smooth, seamless surface that the ink or paint cannot penetrate.” Local councils and public transport authorities are most likely to seek advice from consultancies such as Remedy. Rolling stock for trains, trams and busses usually have a strong, non-sacrificial polyurethane coating that can be cleaned relatively quickly. C&P2015 in Adelaide was a worthwhile event for Mr Rigby. “Corrosion crosses a range of disciplines and the conference attracted a good mix of people including engineers and experts in addition to asset owners and managers,” he says. In the continuing efforts to minimise the impact of corrosion, new materials are being developed to build structures and procedures implemented that have been designed to protect both new and existing facilities. Infracorr Consulting, a national engineering company, has been working on a project where PVC sheet piling has been used in the building of new wharf facilities. The polymer material was adopted to mitigate the future risk of accelerated low water corrosion, a microbially induced corrosion mechanism with reported corrosion rates in excess of 1 mm of material per year. Engineering manager at Infracorr Consulting, Senator Nick Xenophon.


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