C O N T E X T 1 4 1 : S E P T E M B E R 2 0 1 5 7 Periodically The arrival from the USA of the Association of Preservation Technology Bulletin is always eagerly anticipated here. The latest issue (Vol XLVI, No 1, 2015) has been the subject of a smart graphic redesign, the first in 24 years. The much greater use of colour does much to enhance the presentation and technical content. Readers may recall that several recent issues have been devoted to the exemplary conservation of cast and wrought iron, and iron and steel. The latest issue is an invaluable special issue on the conservation of modern metal finishes. It stems in part from the formation of the APT’s Technical Committee on Modern Heritage and particularly on the outcome of its 2013 workshop. Alan Pense begins with a discussion of some of the ways in which metals degrade in use. He restates some of the fundamental structures and properties of principally iron-based materials from a metallurgical perspective for those who might not have read about these in earlier editions of the Bulletin. The explanation in relation to types of degradation and the effects of corrosion at microstructural level are commendably clear. Xsusha Flandro and Helen Thomas-Haney provide an overview of the common finishes applied to architectural aluminum from the 1920s to the 1960s, and the associated conservation and maintenance issues. In the inter-war period aluminum was advertised as ‘defying the corrosive attacks of smoke and fumes’, but this was not necessarily the same as resistance to corrosion and did not obviate the need for maintenance. Without care of the protective finishes, the underlying material would fail. The authors explain that the challenge of restoring deteriorated aluminum finishes in situ (as many elements can not be restored off-site) requires some creative thinking. Historical information must be combined with accurate material analysis to develop appropriate conservation strategies. Nickel and aluminum alloys sometimes referred to as ‘nickel silver’ were popular for art deco architectural decoration in NewYork, particularly after the first world war. Richard Pieper discusses these often vaguely defined and popularly known term ‘white metals’, as applied to the unfinished surfaces. Although superficially similar, these could encompass nickel silver, Monel (an alloy mainly of nickel and copper), lead, stainless steel and aluminum. All of these have dramatically different properties and conservation concerns. Because of the exceptional durability of the ‘white metals’, methods for their refinishing and maintenance are not yet as standardised as those for iron, steel, zinc and copper alloys. However, the author is confident that new models for identification and treatment will emerge as the buildings using these metals age and more work is undertaken. The finishes, investigation and conservation considerations of metals used in historic buildings of the modern movement is covered in a very informative article by Jamie Clapper Morris and Deborah Slaton. The analytical techniques for identification and assessment are discussed in detail. There are four case studies of restoration approaches, including the painted steel used at the Eames House in California, and the stainless steel used on the Gateway Arch, St Louis, Missouri. The final article by Thomas Jester deals with aluminum finishes in post-war architecture. Architects intrigued by the opportunities and possibilities for expression of form and the wide range of finished offered by manufacturers triggered a tremendous growth in applications and technological advances in the 1950s. These uses have now reached the point where renewal is increasingly frequently required. Jester argues that a full understanding of the range and complexity of the material is needed. A return of the Bulletin’s valuable eight-page pullout Practice Points feature is also welcome. The preceding one had appeared as long ago as 2011. The latest (No 13) deals with data interpretation and early corrosion testing for historic concrete buildings. This edition of the Bulletin is well worth seeking out. The current annual Transactions of the Ancient Monuments Society (Vol 59, 2015) carries the concluding part of the two-part examination by John McCann, Pat Ryan and Beth Davis of extant buildings devoted to deer hunting up
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