Aims and
Objectives
The aims and objectives of the
dissertation are to conduct a detailed investigation into
the use of Totternhoe Stone since early times, the problems
encountered today and the current methods of conservation.
These were pursued by undertaking secondary level research
into archive material, published material, site
investigation and consultation with those involved in the
subject.
Source of Totternhoe Stone
Totternhoe Stone is a hard chalk stone that was originally
mined at Totternhoe in Bedfordshire. This stone occurs in beds
throughout Berkshire, Oxfordshire and Buckinghamshire with the
thickest beds developed through Bedfordshire, Hertfordshire and
Cambridgeshire. There is a much thicker bed found in a geological
channel feature at Totternhoe and this is where the medieval
mines were located. Today Totternhoe Stone is extracted as a
small scale concession from the open cast quarry at Totternhoe;
the overburden is used for agricultural lime.
Use of Totternhoe Stone
Totternhoe Stone has been used as a building material since
Roman times. Production of the stone probably reached its peak
during the church rebuilding programme that took place after the
Norman Conquest. Totternhoe Stone continued to be used throughout
the middle ages and through to the end of the nineteenth century.
Today it is available once more for small scale conservation work.
The stone has been used for structural work in columns, arches
and external walls. It has also been used externally for facework
and ashlar. Internally it has been used for decorative features
and screens. Totternhoe Stone has been used across a wide area
centred on Totternhoe in Bedfordshire. It was particularly
popular because it is one of the hardest stones that can be cut
by hand.
Problems in Buildings
Where unprotected, Totternhoe Stone has a limited life. It is
a relatively soft stone and if exposed to the weather it will
decay rapidly mainly as a result of frost action and salt
crystallization. This can lead to major structural failure where
extensive repairs will be required. The frost action and salt
crystallisation will cause rapid exfoliation of the stone
eventually leading to the need for replacement. Defective
building construction can also leave the stone unnecessarily
exposed to inclement weather and other forms of decay. Previous
harmful intervention, in particular cementitious repairs can also
exacerbate the problems of decay.
Solutions in Conservation
The methods of repair and maintenance will require careful
consideration to avoid unnecessary or incorrect interference with
the stone structure or surfaces. Conservation philosophy will
require the minimum intervention in order to retain the
historical aspects of the building. Where structural failure has
occurred the repairs are likely to be quite radical in their
nature although where possible alternatives to complete
rebuilding are preferred. The use of lime is of paramount
importance in conservation work, in the form of limewater,
lime mortar, limewash or lime shelter coating. Where following the "lime method"
the repair will involve consolidation with lime water, redressing or
carefully removing decay back to sound stone, mortar repairs and
finishing with limewash or a lime shelter coat to heavily weathered
stone.
Replacement of defective stone is a last resort and Totternhoe
Stone is now available for this work rather than the previous use
of clay tiles. Bath stone is often used in the more exposed positions for
example over window heads. With the continuing fashion since Victorian
times to scrape and expose stonework, the traditional limewash finish is
still being omitted leaving the Totternhoe Stone exposed to rapid decay,
in a way that was never intended by the original builders.
Conclusion
The last 150 years have seen much restoration work, some which
was destructive, and the old methods of limewash protection to Totternhoe
Stone died out after the First World War. Conservation philosophy requires that all
repairs should conserve as found. Consolidation of decayed stone
is used to retain the historic interest in particular with carved
work and new Totternhoe Stone is used where there is no alternative
to stone replacement. Where used externally Totternhoe Stone should be protected
with limewash applied at regular intervals, heavily decayed stone should
be protected with a lime shelter coat.
Recommendations
All conservation work should follow the original methods which
have been proved over more than 1000 years. All exposed Totternhoe Stone should be conserved and consolidated
with limewash to
retain the historic interest. Replacement stonework should use
new Totternhoe Stone to match the original and to support the
small scale quarry operation. The traditional materials and
skills have been resurrected for conservation work and these should now be used
where ever possible to protect all historic buildings.