discarded on the assumption that they are a mass-produced factory product. Apart from these dramatic examples plastics became widely used to replace more traditional materials, sometimes imitating their appearance but often establishing their own image. These are now to be found in virtually every aspect of the finished building and its construction. Many plastics degrade quite rapidly despite an image of indestructibility. Museum collections have already suffered major losses and polymers such as cellulose esters develop an acidic bloom which can affect other nearby materials. While most of those used in building are less aggressive, many plastics are difficult to repair or have been found to be hazardous materials which need to be replaced. The question of appropriate conservation raises philosophical issues: while the principle of the retention of original material may be very relevant to a material where each piece is unique, such as stone, is it still true where a manmade polymer can quite easily be replicated. Record rather than retain may be the most appropriate response in many cases. For the Conservation Officer it is a matter of knowing what may be of interest; early Bakelite door knobs will often have been replaced by more modem aluminium handles but they already have a collectors' value and before long an interior which still has plastics door Prefabricated Relay Cabin using GRPpanels by Mickelover Transport. By courtesy of Percy Rebottl. fumiture from the 1930s will probably be worth preserving. Decorative laminates with one-off designs are certainly worthy ofa second look and even plastics cladding systems can be of sufficient interest to specialist groups which would like to record their presence and in some cases arrange for sample panels to be kept in museum conditions. Some buildings, such as the rail relay cabins (the author would be very interested to learn ofany surviving examples), might well be appropriate for listing on account of both technical innovation and their interesting building form. SOURCESOF INFORMATION. Plastics Historical Society 11Hobart Place London SWl WOHL, tel: 0171 245 9555 Cook, Patrick, and Slessor, Catherine: Bakelite. Apple Press, 1992. NEWTECHNOLOGY FORCONSERVATION ® ® Katz, Sylvia: Plastics. Studio Vista, 1978. Katz, Sylvia: Classic plastics. Thames & Hudson, 1984. Kaufman, M: The first century of plastics. ThePlastics&Rubberinstitute 1963. Sparke, Penny (Ed.): The Plastics Age. Victoria and Albert Museum, 1990. Walker, A.: 'Fiber-reinforced-plastics and decorative laminates' in Jester, T. (Ed.): Twentieth Century Building Materials. McGraw-Hill,New York, November 1995. Walker, A.: 'When the artificial becomes real' in Slatton, D, and Shiffer, R. (Ed.): Preserving the Recent Past. Conference publication, Historic Preservation Education Foundation, Washington,1995. Walker, A.: 'Plastics: the building blocks of the twentieth century', Construction History Journal, 1994, vol. 10, pp.67-88. Anthony Walker is an architect in private practice with a special interest in the conservation of buildings of the 20th century, and in particular the technology and materials of the era including the uses of polymers. As a committee member of the Plastics Historical Society he is responsible for establishing a database of information about plastics and would be pleased to receive information or questions about any significant use in buildings. He can be contacted at his practice Damond lock Grabowski & Partners, 12 Sutton Row London, WlV6AB, ,et: 0171-439 6701 fax 0171-734 1793. IN SEARCHOF CONCEALED TIMBERDECAY Chris Cullen describes methods of searching out the causes of decay EXTENSIVEEXPOSURE Dry rot and death watch beetle are often heralded as the most destructive pests in our historic buildings, but neither causes so much damage as the misguided determination to pursue all evidence of decay ruthlessly to its furthest extent. Fears of extensive concealed damage frequently result in over-zealous exposure work and in some instances the expense of reinstatement can ultimately be so extortionate tl1at finishes may never be replaced. Major recommendations for minor problems not only divert lin1ited resources away from more important conservation repairs, but tl1ecombination of investigation and treatment is commonly more destructive tl1an the problem they are supposed to eradicate. In the last issue of CONTEXT49 Context, Jenny Carllie highlighted just one example of this unfortunately regular trend.* Opinions range from a belief that all timber buried into external walls is bound to be decayed, to convictions that all old timber must be exposed and treated simply because it never has been. Extraordinarily destructive measures are taken to expose tin1ber in order to treat it as a precaution against problems which have never occurred. Conversely, principal structural elements in the vicinity of serious decay may inadvertently not be investigated because the presence of concealed timber is not anticipated. * CARLlLE, J.: 'The curse of the dead death watch beetle', Context 48, December 1995, pp26-27. So how can all the risks be assessed without wholesale stripping out? There is no standard solution, but a pool of techniques is available and with experience these techniques can be adapted to investigate most situations. CONCEALEDCAVITIES It may seem insulting to suggest lifting floor boards or removing access panels, but unfortunately Iso frequently see such tota:ilyinappropriate exposure work that the opportunity clearly needs to be recommended. All too often a hole issmashed· through a damp stained ceiling to avoid awkward, dirtyroofspace access orwhere afloor board could have been lifted above. To lift individual boards rather than to break up the floor is often a skilled task 13
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