Page 109 - The Building Conservation Directory 2013
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t w e n t i e t h a n n i v e r s a r y e d i t i o n
t h e b u i l d i n g c o n s e r vat i o n d i r e c t o r y 2 0 1 3
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3.2
Structure & Fabric :
Masonry
SCULPTURE
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CLIVEDEN CONSERVATION WORKSHOP LTD
South East, Head office – The Tennis Courts, Cliveden Estate,
Taplow, Maidenhead, Berkshire SL6 0JA
Tel 01628 604721 Fax 01628 660379
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West, Bath office – Home Farm, Ammerdown Estate,
Kilmersdon, Bath, Somerset BA3 5SN
Tel 01761 420300 Fax 01761 420400
Email
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East and North, Houghton office – The Old Coach House,
Houghton, Norfolk PE31 6TY
Tel 01485 528970 Fax 01485 529336
Email
SCULPTURE
: See also: display entry and profile entry in Stone, page 100.
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MICHAEL MAJOR SCULPTURE AND CONSERVATION
10 Randall Garth, Driffield, East Yorkshire YO25 5PE
Tel 01377 250382 Fax 01377 250382 Mobile 07929 798825
Email
SCULPTURE CONSERVATION
: Michael Major Sculpture and Conservation,
established in 1993, is located on the Castle Howard Estate in North
Yorkshire. Michael Major has completed several projects for historic
houses and the main area of work involves conserving 18th- and
19th-century lead sculpture. Limited edition, high quality, new lead or
composite sculpture can also be commissioned, and a full mould making
service is available. The workshop uses traditional and modern materials
and original sculpture is also created, from concept to completion.
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NIMBUS CONSERVATION LIMITED
Eastgate, Christchurch Street East, Frome, Somerset BA11 1QD
Tel 01373 474646 Fax 01373 474648
Email
STONE CONSERVATION AND MASONRY
: See also: display entry and profile
entry in Stone, pages 102 and 104.
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RUPERT HARRIS CONSERVATION
Studio 5, No 1 Fawe Street, London E14 6PD
Tel 020 7515 2020 Fax 020 7987 7994
Email
CONSERVATORS OF FINE METALWORK AND SCULPTURE
: See also: display
entry in Bronze Statuary, page 110 and profile entry in Metalwork, page 134.
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SALLY STRACHEY HISTORIC CONSERVATION
The Barn, Temple Cross House, Lower Godney, Wells,
Somerset BA5 1RZ
Tel 01458 832441 Fax 01458 832567
Email
REPAIRANDCONSERVATIONOFSCULPTURE
: See also: profile entry in Stone, page 104.
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SIMON SWANN ASSOCIATES LTD
Avocet Cottage, West End Corner, Wrentham, Suffolk NR34 7NF
Tel 01502 676044 Mobile 07941 827310
CONSERVATION OF SCULPTURE, ORNAMENT AND DECORATIVE SURFACES
:
Simon Swann Associates works on historic buildings, churches and
monuments across a range of materials providing the hand skills and technical
knowledge to conserve and restore fine architectural detailing. Specialist
areas include sculpture; conservation of architectural ornament in stone;
plaster; terracotta and Coade stone, including historic brickwork and lime
mortars. Reports and investigations for listed building consent etc. The firm
has specialist knowledge of Pulhamite rockwork, Parker’s Roman cement, and
related early cement usage in 19th-century architecture and garden landscapes.
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V A CONSERVATION
Falcon House, 643 Stratford Road, Birmingham B11 4DY
Tel 07522 347543
Email
SCULPTURE, STONE AND ARCHITECTURAL CONSERVATION SPECIALISTS
:
See also: display entry in Stone, page 104.
thankfully this was not the case. The effectiveness of consolidation of
this kind outside the museum environment is still widely held to be
unproven and should only be attempted as a last resort.
Descaling is another issue that often requires consideration
on sandstone masonry projects. Graham Lott (p95) refers to the
characteristic of some sandstones to be more fissile along the natural
bed due to layers of micaceous particles. This has the benefit of
enabling paving flags and thackstone for roofs to be riven rather than
sawn, but it can pose a serious problem in masonry walls if the stone
is ‘face-bedded’ with its natural bed parallel to the face as it has a
tendency to delaminate in scales. (Face-bedding sometimes happens
when the quarry has limited bed depth available for the face sizes
desired.) Once delamination starts there is little that can be done to
stop it, as moisture penetration leads to freeze thaw action and/or
salt crystallisation, causing the stone to cleave along its weak point. It
helps to keep the stone as dry as possible from above and below, and
by ensuring that the surface remains as porous as possible, as this
moderates water vapour pressure in the surface layers of the stone.
Consolidation, on the other hand, is virtually impossible to achieve
without exacerbating the pressure between the layers of stone. One
drastic option is descaling so that water is not retained between
the layers, but this is a highly destructive and disfiguring process.
Descaling should only be done with considerable care or where there is
imminent risk of injury from falling masonry.
Cleaning
Finally some points about cleaning of sandstone as this is still a hotly
debated subject. There have certainly been some serious errors made
in the past and not least at St George’s Hall where previous attempts
at both chemical and air abrasive cleaning have left permanent
damage. The use of acidic cleaning agents caused etched runs and
ferric oxide blotches where mixtures were too strong, dwell times too
long and neutralisation not good enough, while the use of abrasives
led to ‘leopard skin’ patterning and physical pitting. There was also
algal soiling which was partly caused by the use of chemicals of too
great a strength.
As the high quality siliceous Derbyshire Gritstone on this building
had generally proved to be an extremely resistant and durable stone,
it was considered that there was justification on this project to try
to rectify some of the previous aesthetic damage. After a great deal
of discussion and trial sampling, a combination of hot steam and
chemical cleaning was developed. The steam removed and moderated
the reappearance of algae, slimes, moulds and lichens, while a series
of very weak well neutralised hydrofluoric acid treatments with short
dwell times evened out the variation in soiling left by the previous
attempts. This combined low impact cleaning approach has been very
successful at St George’s Hall and on similar buildings, but caution
should always be applied to the use of ‘standard’ cleaning methods
without extensive investigation and trialling due to the variations in
the constitution of sandstones.
Jamie Coath
is a partner with Purcell (see page 31).
Molten lead filling to coping sky joints at St George’s Hall
