‘The
Pride of Beaminster……its glorious tower, unrivalled in the county,
this gracious golden brown tower is worth a pilgrimage to see.’
Sir Frederick Treve – Highways and Byways of Dorset.
The
tower of St Mary’s, Beaminster is the finest such structure in Dorset.
Architecturally it is influenced and in turn influences the
churches of the three surrounding counties of Dorset, Somerset and
Devon. The tower built in
the first decade of the 16th century mainly from the mellow
golden Ham Hill limestone, is gloriously adorned.
Pinnacles bristle out from every angle and elevation, saints,
beasts, grotesques and demi angels look down from every possible vantage
point, drawing the eye ever upwards.
At the heart of this exuberant tower is a wealth of beautiful and
intriguing early 16th century relief sculptures, (related to
contemporary alabasters), depicting the life of Christ, including -
unusually – Resurrection and Ascension scenes.
These panels are of great interest, and are unique in-situ
survivals of this date. They are made more interesting by the unusual
addition of two lay figures flanking the upper scenes who, are
understood to be a packman (or perhaps a pilgrim) and a fuller.
The central scene is a Crucifixion flanked by the Virgin and St
John, set as if within a western window and surrounded by angels.
On the lowest level of these scenes is a Virgin and Child with a
kneeling donor figure, set in a large pinnacled tabernacle –like
niche; she is flanked by two saints in niches, one being St George and
the Dragon. Extending all
round the faces of the tower at this level as if it were some heavenly
ground beneath the Virgin’s feet is a broad decorative frieze
depicting star-like swirling traceried roundels and floral quatrefoils.
At the lowest stage of the tower, set on the buttresses flanking
the west door and large west window, are a further six niches now
containing figures of a Victorian date.
The use of the faces of the buttresses to accommodate niches is a
motif usually associated with cathedral rather than parish church
architecture and is thought to be unique. The upper two west facing
Victorian sculptures begin the Christological narrative with an
Annunciation. The rest
depict saints. From this
brief description we can see that St Mary’s Parish church at
Beaminster carries an extraordinary amount of narrative and decorative
detail. The
tower and church is not only an imposing structure but is the focal
point of the historic town of Beaminster and intricately woven into its
history and people’s affections.
By the end of the 20th century the fabric of the tower was
desperately in need of careful conservation and repair due to the
effects of both natural weathering of the stone, air pollution damage
and the past use of inappropriate materials.
The architectural lines and sculptural forms had become difficult
for the viewer to appreciate. This
was not only due to the continuing loss of detail but also the presence
of lichen growth over all surfaces. Ham
Hill stone has been used for all the carved detail of the tower.
This limestone is particularly sensitive to the effects of
incorrect bedding resulting in weathering through the exposed beds of
the stone causing lamination, loss of detail, spalling and cracking.
The second factor affecting the long- term stability of the stone
is the presence of clay/sand beds which are more vulnerable to erosion
than the surrounding stone. This
produces the traditional striated weathered appearance.
This erosion, which is has a more serious effect on incorrectly
bedded stones causes large pieces of undercut decoration to fall away be
lost. The condition of the stone had further deteriorated through the 19th
and 20th century due to the increase in acidic atmospheric
pollutants from the local industries and the application of
inappropriate repair systems such as hard cement mortars and the
introduction of iron fixings. The rate of decay had dramatically
increased since a photograph of the west front was taken in 1938 now
located in The National Monuments Record Office. The church is a very busy public building with numerous activities taking place in and around its structure. The tower has sixteen tall pinnacles with a stockade of pinnacles around the higher stair turret. Lower down there are pairs of rather remarkable slender projecting pinnacles set around the tower on the buttresses at two levels. These striking features are supported by large corbels carved in the form of grotesque beasts. Beaminster tower has an extraordinary history of its pinnacles behaving more like missiles, hurtling down from above at regular intervals. The central east pinnacle on the parapet has fallen down no fewer than three times and the archaeological survey revealed further disasters with the pinnacles throughout the church’s history. Many of them were constructed with poor or inadequate fixings and were showing signs of serious weathering through the weak beds of the stone. They posed a real danger to the public below and to the building itself.
From
the beginning of the project it was decided to make every attempt to
preserve all the stone in situ and especially to value every mediaeval
and Victorian carving no matter how decayed, fractured or damaged.
An archaeological survey ran in conjunction with the conservation
programme and together with the architect’s specification set the
framework for the repair and protection of the stonework. It was also
decided to use techniques of conservation compatible with the chemical
and physical characteristics of the original limestones and lime
mortars. This form of
treatment is most commonly referred to as The Lime Technique or Method. The
application of the lime technique can be broken down as follows:
(For
a more detailed explanation see The Technical Document.) Every
stone of the tower was inspected and treated where necessary.
The main items of the conservation work were as follows; all the
crowning pinnacles required dismantling and re-fixing. A number of the
projecting pinnacles needed similar treatment with the addition of
specially engineered supports to the corbels beneath.
A stair turret pinnacle needed to be replaced with a new carving.
The upper windows of the tower were badly decayed and needed
extensive repair after removal of the previous applications of cement.
Similarly all the cement repairs and, in some areas iron pins,
needed to be removed from the decorative friezes as both were causing
deterioration of the surrounding stone.
The upper frieze was very badly decayed in places, and here
skilful repairs were needed to enable the recovery of most of the form.
The condition of the sculpture, which were face-bedded Ham stone
in the case of the 16th century work or edge bedded in the
case of the Victorian work, demanded urgent pinning and repair to fix
and protect them from a developing state of lamination.
This decay mechanism had affected most drastically the figures on
the lower half of the tower, mediaeval and Victorian alike.
In addition to the work on the decorative elements, the jointwork
across the whole tower needed to be inspected. If it was found to be
faulty or if the cement needed to be removed it was replaced with a
lime-based mix that was carefully matched with the very satisfactory
lime mix with which the majority of the jointwork had previously been
repointed in 1876. The
lime techniques of stone conservation had been developed for the major
project of conserving the vast collection of mediaeval statues at Wells
cathedral in the 1970s and 1980s and have been used extensively on
countless major historic building conservation programmes in Britain and
Europe. The undoubted
success of this treatment which draws on traditional materials and
craftsmanship combined with a deep understanding of the behaviour of
stone and lime has ensured the continuation of a tradition of repair
which is thousands of years old. The
team assembled for Beaminster included sub contractors who along with
the Stracheys formed part of the team at Wells Cathedral.
In the succeeding twenty years they have pioneered improvements
of these techniques, getting to know how these respond to a variety of
stones and weathering conditions. This
wealth of expertise has been applied at Beaminster in every aspect of
the work. This project
comes at a time when the lime method is being evaluated by the Heritage
agencies and fellow professionals, and should provide further research
in this field with a key site for future monitoring and review. It
is not only the technical skills of the conservators but also their
aesthetic approach, which have ensured a successful result at Beaminster.
This has much to do with the senior conservators early training
which underlined a deep understanding of the lime technique with a
certain discipline and aesthetic of repair.
Working with decayed and damaged statuary and architectural
decoration requires a deep respect for original craftsmanship and
artistry and then working with remaining forms to enhance them without
falsifying them or adding anything at all conjectural.
To achieve a level of aesthetic unity in the treatment of a
complex surface with such a range and richness of colour demanded both a
technical and intuitive response.
The proper and selective use of a skilfully colour-matched and
unobtrusive sheltercoat, enhancing the natural polychromy of the
contrast between Ham stone and the local oolite, has re-established the
intention of the designer in defining the divisions of the architecture
and of the decorative bands and panels. The
level of meticulous investigation and recording at Beaminster has in the
past generally been reserved only for cathedral-status projects.
The in-depth archaeological investigation of the tower enabled
the retrieval of the construction and repair history; while the
meticulous recording of the conservation passes down to successive
generations the resources needed to continue the preservation of the
carvings and to assess the efficacy of our methods through long term
monitoring. Without the
care of the conservation team and the expertise of the archaeologists
the significance of many of the observations would have been missed.
The analysis of the building and repair phases of the tower would
not have been possible, and perhaps above all the recognition the
exterior of the tower was richly painted would have been missed.
Traditional
lime putties, which provide the central material for the lime technique,
although extensively used in the past centuries and millennia are now
hard to come by due to the industrialisation of the lime industry.
However a Welsh coal fired lime produced by a skilled craftsman
to exacting standards does possess all the characteristics of the
traditionally made lime. This
practice has used Bryn Gilbey’s lime for a number of years and chose
his five year old lime, which has considerable plasticity and setting
qualities for the repair mortars to all the sculpture and architectural
detail on Beaminster tower. Studies
in the field have led many to believe that the performance of
traditionally made putties, which have matured for some years possess
qualities of durability unmatched by industrially produced products. Throughout
the project the clergy, churchwardens, parishioners and residents have
shown a strong interest in the work and the team have always taken the
time explain progress and conservation techniques.
The completion of the work was marked by an exhibition of text,
drawings and photographs telling the 500 year old of the tower.
The exhibition included photographs of the sculptures as works of
art by a professional portrait photographer.
An evening of lectures was held in the church shortly after the
scaffold was struck. The
dissemination of information is an important aspect of stone
conservation. Many members
of the team give lectures on conservation and building archaeology to
students at schools, colleges, universities and to delegates at
conservation conferences. The work at Beaminster provides excellent
illustrative material for conservation teaching purposes as it shows the
necessary high standards of work required of those who aspire to enter
the profession. In April
four SPAB scholars spent a day on site to look in detail at the work as
part of their programme of study. An
illustrated summary of the work will be available on our web site to
facilitate more widespread access.
A unified archive of the field records will be deposited in The
Dorset Record Office with a copy of a synthesised report containing the
results and conclusions of the work, which will be more widely
available. It is also
intended to produce a short article for publication in the Proceedings
of The Dorset Natural History and Archaeological Society.
It is hoped that some of the sculpture photographs will be on
permanent display in the church and the information from the survey will
be incorporated in any future church guide. A
contract of this size needs careful planning and diligent management if
it is to be kept to time and budget.
Key elements are Health and Safety; the appropriate choice and
number of the workforce, including apprentices, to create a
multidisciplinary approach, which with careful management, supported by
good lines of communication, allows the work to be carried out in a
harmonious and efficient manner. At the start of the contract a schedule
was made to provide a framework in which to set weekly and monthly
targets to monitor progress and to provide accurate information for the
monthly valuations. The
supply of materials at the right time and on time is crucial to a
project of this size. The
importance of good relations between the main contractor and the project
supervisor, in this case the church architect, must be emphasised,
particularly in the close cooperation of working through and adapting
the specification where necessary.
The core methods of stone conservation, which were used at
Beaminster were laid out in the original tender documents and
specification put together by the architect, well in advance of the
contract, in consultation with English Heritage and a delegated stone
conservator. We
are a medium sized commercial stone conservation practice and are
obliged to win contracts through open tender.
In spite of being in this competitive world of historic buildings
conservation where the lowest tender wins the work, the conservation and
repair project at Beaminster Church has been carried out with an
enlightened approach of drawing on skills of highly experienced
professional colleagues in the conservation field.
Along with the company’s in –house team of conservators,
craftsmen and women, specialist sculpture conservators, recording and
site archaeologists have been employed or invited to make use of the
access to the tower. This healthy mix of expertise from both within and
outside the company has led to continuous discussion and fine -tuning of
the methodology and conservation techniques.
The experience of conservation and archaeology colleagues who
have worked on Cathedrals, Churches and Historic Houses all over
Southern England coming together at Beaminster has been mutually
enriching for all concerned. During
the work at Beaminster the team worked tirelessly not only to improve
the condition of the stone but also to improve the appearance of the
tower and to make the extraordinary amount of carved detail accessible
from the ground. We hope
that now passers by will be encouraged to stop, look up and see
something of the intention of the original builders.
Beaminster town and the Church welcomes many tourists and the
care not only of Beaminster tower but all such landmarks enriches the
landscape for both the local community and visitors.
Introduction The
technical information here will be divided into the following sections: 1.
Description of the
original Materials 2.
Decay Factors 3.
The Lime Technique 4.
The Archaeological Survey
1.
Original Materials The
tower is constructed in a mixture of Ham Hill stone and a similar local
Limestone of Liassic nature. The
latter is of inferior weathering quality due to its more varied and
softer composition. Allan
Harvey, the architect for St Mary’s, Beaminster gives a very good
summary of Ham Hill stone in The Preamble to The Description of Works; ‘
Ham Hill stone is particularly sensitive to the effects of incorrect
bedding. The bed heights
available from the quarry were always restricted and so large stones for
decoration, carving, inscription, freestanding sculpture and mullions
were often face or edge bedded.
This results in loss of detail, spalling, cracking and
dramatic loss of detail through lamination.
The second factor affecting the long - term stability of the
stone is the presence of clay/sand beds, which are more
vulnerable to erosion than the surrounding stone.
Face
bedded: this
is characteristic of much of the medieval decoration and in particular
the west front relief carvings. This is where the stone is upended to
give the carver extra height to work with. In this case the beds of the
stone run parallel to the face of the building as illustrated the
carving of St George and the Dragon, Group 4 No 38. Edge
bedded: this
is characteristic of the Victorian sculpture where the stone is upended
and carved with the beds running at right angles back from the face of
the building. The dramatic
lamination of an edge bedded sculpture is seen in the illustrations of
The Virgin Mary, Group 6 No 70. The
medieval mortars at Beaminster are all lime based. However in 1876 a
major programme or repointing the tower with a mix of 3 parts sharp
gravel to one part of Aberthaw lime has proved to be a very successful
material. In this case we
designed our repointing mix along similar lines to that of 1876. 2.
Decay Factors Environmental
pollution: the
location of Beaminster tower is deceptive.
It might appear to be a rural idyll enveloped in clean country
air but the older residents remember the town wreathed in smog.
This pollution was due to the proximity of a gas works and a milk
factory in Beaminster, which combined with emissions from coal fires
would have resulted in the surface of the stone being attacked by the
deposition of acidic atmospheric pollutants in the form of soluble
salts. Porous building materials such as the limestone of Ham Hill are
particularly susceptible to salt decay.
Limestones are formed primarily of calcium carbonate, which is
converted through the presence of acidic compounds to calcium sulphate,
the most common salt associated with stone decay. Cement
repairs: cement
mortars are harder, less porous and less permeable than stone and also
can be another source of sulphates.
The use of cement alongside a limestone such as Ham Hill can have
devastating effects on its condition.
The dense and impervious character of cement mortars prevents the
movement of moisture and soluble salts to the surface but rather
encourages moisture to travel through the original stonework rather than
the repair. Soluble salts
accumulate and crystallise at the interface between the cement and the
stone where they continually break down the core structure. The
different thermal expansion coefficient of the cement and the stone also
causes stress, cracking and eventual loss of original material. Iron
fixings: iron
used as dowel and cramps in stone structures is vulnerable to corrosion
through contact with moisture. This
causes the iron to expand and eventually split the stone it was designed
to secure. Lichen
growth: the
heavy growth of lichen was obscuring much of the fine detail of the
carving and hiding areas of serious decay.
The Natural History Museum identified the lichens as
Placodioid Lichens – Caloplaca flavescens and Diploicia canescens
and Crustose lichens – Lecanora crenulata.
These are all lichens that are frequent on limestone in areas
where there is considerable atmospheric nitrogen. 3.
The Lime Technique Cleaning:
the cleaning chiefly
involved the removal of loose dirt, lichen and mosses, and this was
achieved with the use of scalpels, non-ferrous wire brushes, small
bristle brushes, such as tooth-brushes and stencil brushes and water
spray (the latter kept to a minimum). Before
cleaning began small repairs with adhesive lime mortars were made to
hold areas that were considered fragile, chiefly where cracks had
rendered details insecure. A
light touch was needed on many areas, such as the 16th
century relief panels because the lichen cover could conceal cracks and
weak beds in the fine details and forms. Limewatering:
this is a method of stone
consolidation which replaces lost calcium in friable limestone and
plaster. It is a
traditional method of conservation, which despite continuing research is
not fully understood. The principle is the deposition of calcium
hydroxide into the decayed area where it will carbonate when in contact
with the air. Its purpose
is to replace the calcium that has been lost from migration, gypsum
formation or weathering. At
Beaminster up to 30 applications were made to the reliefs and corbels
where conditions were appropriate.
For example we avoided limewatering near clay beds. Cement
Removal: we
aimed to remove as much of the previous cement repairs as possible.
It was often found that these repairs were associated with iron
or copper dowels. The
cements that were found fell into three phases of work but in all cases
the cement had caused considerable damage to the original stonework. Dowelling:
the dowelling of laminating stone followed on immediately after
the removal of cements and probably formed the major part of the
conservation work on the sculpture.
The main form of decay to which the Beaminster carvings are
subject is the disintegration and washing out of the weak beds, which,
as we have described above, are a characteristic feature of Ham stone.
In the 16th century relief carvings these weak beds
frequently occur in 2-4 cm intervals within the body of the block, and,
in the better stones (such as those from which the Resurrection and
Ascension panels are carved) are only 1-2mm thick; however, at the other
extreme (as with St George and the Dragon block) the weak beds
may be as much as 5mm wide (or up to 1cm at the edges of the stone where
they are fully washed out. In
such extreme instances these weak beds occur at such regular intervals Each
figure, in the panels, was given a number of main dowels, where
necessary, and a range of smaller sized dowels to secure individual
sections. The dowels were
all angled down, and set in adhesive lime mortar.
Where this was not possible, as was the case when fixing the
corbel heads of the angels on either side of the Crucifixion (which are
fixed in their natural beds) the dowels were set in resin.
In all cases the ends of the dowels were sunk 3-5mm beneath the
surface of the stone and capped with lime mortar. Similar
principles were applied to all the sculpture and decorative detail. All
new dowels and fixings are made with Code 316 grade stainless steel. Lime
Mortar Repairs: the
primary reason for mortars is protection; it is to provide a barrier
between the weather, atmospheric pollution and the endangered stonework.
Whether it is a mortar joint to prevent water penetration to a
wall or a repair to a vulnerable piece of sculpture the lime mortar
should have a variety of important properties.
The mortar should match the stone in surface colour and texture.
The
mortar should be softer than the material it is protecting.
It should be porous enough to prevent and interface forming with
the stone where soluble salts can be deposited and recrystallise.
It should encourage residual salts to travel into and through the
mortar so preventing further damage to the stone. The
mortar, in comparison with cement-based mortars, must be easy to cut
back and remove. It is true
that a lime mortar continues to harden and its toughness can only be
judged over a long period of time. The
mortar should have good adhesive properties.
This is dependant upon the quality of the lime, the correct
aggregate ratio and the correct application of the mortar.
For example, sufficient wetting of the prepared surface, the
initial application of a slurry mix, suitable compression and control
over the drying time. The mortar should be malleable but stiff enough to
enable compression without moving the volume from one area to another.
It should never be crumbly.
It should be supple enough to allow pressing into small crevices
and corners, but never sloppy. On
the stonework of Beaminster mortar repairs were used to cap all
vulnerable and friable areas, and to the greatest extent possible to
attempt to fill or cap the many fine cracks in order to prevent the
ingress of water. Deep pits
and the wide voids between laminations were filled in several stages to
allow the mortar to set. Examples
of two lime mortar recipes used at Beaminster: Mix
B. Figure Sculpture
Adhesive Mix. Lime
(5 year old Gilbey)
1 part
Lime (5 year old Gilbey)
6 parts Ham
Hill stone 20s-0s
1 part
Kimbridge
1.5 parts Hornton
Brown stone 20s-0s
1 part
Silver Sand
1.5 parts Kimbridge
sand
1part
Hornton
Brown stone
3 parts Buff
brick dust
0 per cent
Ham Hill stone 1
part
Buff
brick dust 2
parts
All passed through an 80s
sieve Sheltercoat:
this is the final stage of
the lime treatment. The
ingredients for the sheltercoat are similar to that of the mortars with
in some cases the addition of casein, which has waterproofing qualities.
The consistency of the sheltercoat should be similar to thin
cream and applied to the surface in up to three thin coats.
Each coat is carefully rubbed back and the drying out of the thin
layers closely controlled. The
purpose of the sheltercoat is to provide a physical barrier against
weathering as well as knitting together both physically and visually the
original stone surface with the lime mortar repairs.
The sheltercoat should fill all the fine hairline crack and
cavities that are too small to be repaired.
This final coat is useful in those undercut surfaces which are
more likely to form soot crusts, by acting as a barrier between the
original stone surface and future soiling.
This should make cleaning these surfaces easier in the future. If
used with great care and consideration for the original surface, the
sheltercoat can enhance the visual appearance of the object or
structure. Examples
of two Sheltercoat recipes used at Beaminster. No. 16 used for string course, frieze, grotesques Lime
(5 year old Gilbey) 80s-0
1 part Ham
Hill 80s-0
1.5 parts Hornton
Brown 80s-0
1.5 parts Slate
80s-0
1 part Raw
Sienna
2/16 Casein
1/16 No 28 used for some of the Victorian sculptures Lime
(5 year old Gilbey) 80s-0
1 part Raw
Sienna
.5 Raw
Umber
1/16 Casein
1/16
An
archaeological survey of the tower was carried out to record in detail
its medieval and later fabric, recognise and record periods of
construction, decay, repair and restoration and using documentary
evidence, provide a chronological framework for these processes.
The site archaeologist worked closely with the masons and stone
conservators so that it was possible to recognise and categorise earlier
periods of repair and conservation.
This multidisciplinary approach enhanced each area of information
enabling a comprehensive story of the tower’s five hundred years to be
established. Detailed
research using original documents in the Dorset Record Office provided a
chronological framework and detailed information about the last 150
years of repair and conservation of the tower.
Working from the scaffolding, a clear objective record, drawn,
written and photographic of the tower’s stonework and sculptures was
made. Scale drawings at
1:10,1:20 and 1:100 were made; detailed notes on masonry and each
sculpture; and a black and white photographic record.
The scale drawings provided the framework for the record of the
present conservation work. The archaeological record succeeded in demonstrating the processes of weathering and decay to which the tower has been subjected as well as the different approaches to its repair, restoration and conservation over the last two centuries.
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