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Technical Q&A 23 : Decorative Leadwork
A. The
artistic skills of the leadworker have typically found expression on rainwater
heads, downpipes, water cisterns and roof embellishments, as well as statuary.
Employed
on numerous ecclesiastical and important secular buildings, decorative leadwork
reached its apogee from late medieval times up to the end of the 18th
century. Despite the fine craftsmanship, much of Britain’s historic leadwork has
been lost or is threatened. Not only is there a lack of appreciation of
decorative leadwork and its conservation, even non-ornamental plumbing leadwork
skills are now scarce.
A. Decoration
is formed either by working lead sheet with tools, or casting molten lead
directly into moulds. Plumbing leadwork skills, such as joint solder wiping and
pipe fabrication, are required as well as specialist decorative techniques. Decorative
interest can be created by: dressing lead over moulds to form shapes such as
faces (repoussé work); carving with gouges or forming pierced tracery with
chisels, punches and knives; beating into ornate finials, crestings etc
(wrought work); and casting into open sand, chill or other types of mould. Surface
decoration is also possible.
A.
Frequently. We have become accustomed to the attractive silvery grey finish of
architectural leadwork. Historically, whole roofs, girouttes, flèches, ogee
domes, lanterns, pennons and spires offered dazzling displays of chequer-work
and chevrons. Rainwater heads and cisterns, too, were treated colourfully. Surface
decoration was achieved by gilding, tinning, painting and, sometimes, through
artificial patination, mastic inlays or etching.
A. Though
lead is highly durable, degradation can occur. Some problems are associated
with lead in general, such as acid corrosion or, with roofs, thermal stress
failure. Defects specific to decorative leadwork range from the deterioration
of wrought iron armatures and cores in cast objects to damage by birds to
delicate tracery. Weathering degrades gilding, tinning and paint.
A. Lead is
the perfect material to repair. It is possible to cut out a damaged section and
insert a matching new piece (sand-cast or milled, as appropriate) to produce an
invisible joint. Soldering and solder wiping are often used here and for making
good small splits and pin-holes in decorative work. Where a rainwater head is
in very poor condition, a new lead reservoir can be made and placed inside,
with suitable reinforcement. Occasionally, a case exists for re-shaping
distorted leadwork, such as when a piece no longer functions as intended (obstructing
water flow etc). Work may also entail casting new parts or replacement of
corroded wrought iron armatures with stainless steel.
A. It is
important to copy the original method of jointing lead, in most cases to avoid
changing the fundamental nature of a historic piece. There are many examples
where unskilled individuals have tried to replace soldered joints by
leadburning (welding) inside restricted rainwater head reservoirs, leaving
globules of molten lead that cause debris to collect. Smooth wiped soldered
joints would have been easier to perform to the benefit of water flow. Regardless
of the method, remember fire safety with all hot work.
A. Gilding,
painting and other forms of surface decoration might be considered where it is
known to have existed originally and would be to the benefit of the architectural
whole. Lead-based paints were used historically, but legislation now restricts
the sale of these for use to grade I and II* buildings, scheduled ancient
monuments, and also works of art, which some decorative architectural leadwork
objects might be classed as. Listed building or scheduled ancient monument
consent may be required before reinstating decoration.