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around the crack in the calf revealed very poor quality material in the original casting and a large number of dowels that would significantly weaken this area. However, the thickness of the skin casting was relatively consistent over the whole of the statue.
To carry out a repair in this area that would be structurally sound rather than just cosmetic, it would therefore be necessary to remove the band of material that incorporated all of the disturbed material around the crack, and as many of the dowels as possible, while still being consistent with the constraints imposed by English Heritage. This was achieved by removing all of the cracked and damaged material and then cutting back the edges of the hole until sound material was reached. Two cast aluminium inserts were then prepared using moulds from the Victoria and Albert Museum. The inserts were to be welded in using a tungsten inert gas technique. To
overcome shrinkage problems across the joint, that might possibly cause either distortion or cracking in the statue, the welds were as narrow as possible and built up using fine rods.
The thigh was found to have a plate varying in thickness between 1.5 and 4 mm; the bursting had been caused by a build-up of corrosion products behind this plate. Replacing such a thin patch would have been impractical the same problem would probably recur in the future. It was therefore recommended that the plate be completely removed and the area repaired by building up with weld material before dressing back to the original contour.
It was also recommended that the statue be supported by securing the armature, rather than bolting of the flange around the foot as was done previously. This will relieve some of the stress in the disturbed calf in future.
Although consumables were chosen to match the original casting, problems were encountered with cracking during
welding. It was not possible to provide a normal pre-heat, and following the first attempt at welding, cracking was observed along one side of the weld. After this had been removed, the statue was carefully lagged and hot air blowers used to apply a gentle heat to the area to be welded. This was successful in
overcoming the contraction cracking although examination after completing the weld run revealed a different type of cracking in the centre of the weld. This is known as liquation, or solidification, cracking of the final metal to solidify. Also seen were small blisters or bursts in the original cast material adjacent to the weld. To assess the possible cause of these problems, documentation of previous examinations of the statue was reviewed and the chemical composition for the original casting was found to contain small quantities of mainly silicon, copper and iron.
The quantities of the alloying elements present, when diluted with the pure aluminium welding rod in the weld pool, produce an alloy composition which is most susceptible to solidification cracking. This is due to the long freezing range and the high shrinkage coefficient for this material. To overcome this problem, it was necessary to use welding rods with an alloy content capable of maintaining a lower solidifying range and lower shrinkage characteristics even when diluted into the weld pooi and for this reason small diameter 12% silicon rods were recommended.
The bursting in the original cast material appeared to be due to surface working of the statue resulting in entrapment of material which, when subjected to the heat of welding, rapidly expanded causing this problem. It is therefore necessary to reduce the heat input to the weld and this is done by using smaller diameter weld rods and a lower melting point material, ie eutectic composition 12% silicon weld rods.
The success of these recommendations were proved by liquid penetrant inspection of the welding and surrounding casting after cutting back to the final contours.
The repairs to the statue are not just conservatorial but also of a structural nature and represent an optimum solution to achieve maximum strength with minimum disruption to the statue. Rumours abound each time the statue is taken down, of it being replaced with a replica. However, considering the time that the statue has been on display, there is little evidence of loss in definition due to corrosion, even despite the urban pollution, and if weathering should continue at a similar rate then the statue may remain outside for a great many more years. Provided access to the statue is restricted, to the extent that vandalism can be prevented, then similar damage is unlikely to occur in the future.

Simon Clarke is an Associate of the Metallurgy
Department at Sandberg Consulting. The article is
reproduced by kind permission of Materials World Journal of the Institute of Materials.
Eros returns to site in Piccadily Circus ready for a good many more years.
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