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LEAD
A BASE METAL and one of the heavier metallic elements, lead is notable for its excellent MALLEABLE working properties, as well as it’s exceptionally low melting point of 327.5°C. In the past, lead was an exceptionally popular metal for reproducing landscape and garden sculptures, indeed the metal is still used in the present day for this purpose. Lead is easily melted in hand held ladles via a basic heat source – a propane gas fuelled torch will suffice. It’s ease of use makes lead a popular metal for studio based work, with many artists including Aristide Maillol (1861-1944), Joseph Beuys (1921-1986), and more recently Anthony Gormley (1950-), becoming known for their extensive use of this metal. Some care is essential when using lead in the studio, the metal is toxic if ingested and serious burns can be sustained through mishandling molten material.
The low melting point of lead allows it to be poured directly into a suitable rubber reproduction moulds as well as the more usual high refractory investment moulds. Most of the usable rubbers for this type of casting process are derived from the platinum catalysed SILICONE group of elastomers - though particular care must be taken to follow the rubber manufacturer’s recommendations on this point, as not all silicone compounds are suitable. Using a rubber mould (where practical) circumvents the need to construct a shell or grog refractory mould. It is easy to produce flat or solid designs, however the formation of hollow castings using a rubber moulding technique can involve a considerable degree of planning and skill; invariably first casting, then fabricating together a series of abutting panel sections to complete the piece ‘in the round’. The softness and weight of the metal can make working on lead sheeting and lead casts surprisingly difficult. Larger scale (hollow) designs may require back filling with PITCH or a similar core material to prevent the design from CREEPING out of shape or sagging. An unsupported work can potentially collapse under the it’s own weight, either during making, or later when transported or exhibited for instance.
Lead sheet produced primarily for construction work (usually as a roof flashing), is a popular wrought material with artists. Lead does not WORK HARDEN easily, so the material is easily cut with snips, manipulated and repeatedly worked without need for constant annealing or other heat treatments. If annealing is required, it is better to first spread a coating of tallow over the affected area (this acts as a visual temperature indicator), the lead object is then gently heated with a blow torch until the tallow changes the tone of the lead. The change in tone indictes an appropriate annealing temperature has been reached and the metal can then be allowed to cool before continuing work.
The usual technique for joining lead sections is soft soldering, though the metal can be welded by the TIG process, using cut lead strip as a filler material (again, hygiene and health care should be taken seriously when joining this metal). The ease of folding lead allows it to be readily ‘self fixed’ by the panned down lap joints commonly used by tin and leadsmiths. Lead work is usually finished simply to an ‘as is’ surface condition, though a graphite based metal blacking compound can produce a unified surface finish. Not all art founders are prepared to undertake leadworks, though many will make work to a limited scale. There are still a few small businesses which still specialise in the production of cast lead garden ornaments.
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