[ FoGO ]
Conservation of Early Mediaeval Carved Stones

By

Revd. Tom A. Davidson Kelly, M.A., B.D., F.S.A. Scot.

The story of the Govan collection has been told in detail in the expanded proceeding of the 1992 conference, published under the title Govan and its Early Mediaeval Sculpture. The Govan Sarcophagus was brought into the extended chancel of the church in 1908. In 1926 five hogbacks, three cross shafts and sixteen cross slabs were brought inside. The shaft of the Govan cross ( for about 100 years placed outside Jordanhill House ) was returned in 1928. In April of this year, Hunter & Clark added 4 conserved stones to the 26 monuments on permanent display within the church by fixing two in the Transept and two in the Baptistry, where Stirling Maxwell number 12 and the Cuddy Stone ( Stirling Maxwell no. 9 ) were repositioned.

[ Plate 1 ]
Plates 1a/1b: 'Exhuming' the eight pieces of early mediaeval sculpture buried at the entrance to the churchyard in August 1988

Plate 1 shows eights pieces of stones being removed from the churchyard under the direction of Dr. Colleen Batey of the Kelvingrove Museum. The diagram ( plate 2 ) shows the four stones to be re-assembled from the seven stone pieces collected from Govan Old Parish Church during October 1993. Plates 3-6 show the conserved stones, ready to be returned to Govan. Individual stones are identified by the number given for them in Sculptured Stones in the Kirkyard of Govan by Sir John Stirling Maxwell. The rest of this note is reproduced with kind permission from the final report produced by Historic Scotland on their work at the Conservation Centre, South Gyle, Edinburgh.

CONDITION

No. 31 ( frag. 4 ) Approximately 80% of the carved detail has been lost leaving a 500mm x 150mm area of interlaced carving. The surface of the stone was covered by mud. Removal of the mud revealed drips and splashes of paint. Paint covers almost 10% of the carved surface of the stone. Also, 2 prominent gauge marks, one approx. 100mm x 10m, the second, 90mm x 10mm at right angles to the first appears across the carved surface of the stone. A black sulphation deposit covering over 90% of the stone surface was exposed upon the removal of the mud.

[ Plate 1c, 1d ]
Plates 1c/1d: APRIL 1992: Removing Stirling Maxwell numbers 21, the top half of 23, 31, 36 and placing them in the narthex of the church before conservation. Number 42 was placed under the large tree close to the small side entrance door

No. 21, in 3 pieces ( frags 2, 6 and 7 ) Frag. 2 suffers from areas of surface delamination where the rebate has been dressed around the edge of the stone leaving an exposed body of stone upon the face. All 3 frags have lost a great deal of carved detail. Frag. 6, however, details a carved surface in the form of a 6-cord plait which remains relatively well defined. The broken edges of the frags where the stones butt together are fresh suggesting that the stone breakages are relatively recent. The frags realign well thereby making for a less complicated rejoining process.

[ Plate 2 ]
Plate 2

No. 23 ( frag. 5 ) appears not to have suffered the same weathering process as have the other stones. The soil moulding and faint traces of pattern survive. Diagonal striations appear across the stone surface. This may be due to soft materials within the bedding planes of the stone. The stone is affected to a lesser extent by a black sulphation deposit. A non-contemporary script has been carved into the stone towards the bottom edge. The bottom edge appears to have been sawn rather than broken.

No. 36, in 2 pieces ( frags 1 and 3 ). Both frags 1 and 3 suffer from an advanced loss of surface detail. A non-original script, 'WR', has been carved upside down upon the surface of the stone. The edges where the two stones butt together is relatively fresh therefore making the rejoining process less complicated. Areas of black sulphation deposits exist in places as do tool marks suggesting that attempts have previously been made to remove such deposits.

TREATMENT

No. 31 ( frag. 4 ). The stone was sufficiently protected and transported to our Edinburgh studio. The stone was recorded photographically and its condition was noted. An investigate clean was undertaken to assess the condition of the stone and to select the most appropriate cleaning method. Loose mud which existed to a depth of 5mm in some places was removed using a soft brush and vacuum cleaner. This trial clean was undertaken on a representative area of the stone which, when cleaned, was seen to be in sound condition. Having been assured of the durability of the stone, the mud was washed off using 25 psi water pressure and nylon bristled brush. Having exposed the paint beneath the mud layer, trials were conducted to determine the most effective method of paint removal.

Trials areas were selected. A Sodium Hydroxide poultice was applied to one small area and a layer of water soluble Dichloromethane was applied to another. The latter proved most successfull and the paint was removed by this method. The Dichloromethane solvent and dissolved paint layer were then washed off. The conserved stone was photographed and prepared for its return to Govan.

[ Plate 5 ]
Plate 5: No. 31 ( frag 4 )

No. 21, in 3 pieces ( frags 2, 6 and 7 ). The frags were transported to the studio and recorded. The surface mud was washed off using 25 psi water pressure. The delamination fissures were consolidated by flooding an acrylic resin in solution into the cracks. The frags were rejoined with four, 400mm lengths of 16mm Austinitic Stainless Steel dowel (BS316) and an epoxy resin. Once rejoined, an acrylic resin and stone dust repair material was used to partially fill the joint between the two halves. The repair material was specifically designed, in terms of colour, hardness and texture, to create a material which was sympathetic to the stone itself. The repair material is removable. The stone was recorded in its repaired state and prepared for its return to Govan.

No. 23 ( frag. 5 ) The stone was protected for transportation, recorded photographically in the studio and cleaned using 25 psi water pressure and a nylon brush. The cleaned stone was recorded photographically and prepared for its return to Govan.

[ Plates 3/4 ]
Plates 3/4: No. 21 ( frags 2, 6, 7 ) / Top half of No. 23 ( frag 5 )

No. 36, in 2 pieces ( frags 1 and 3 ). These stones were protected and transported to our studio, and photographed there. The stones were cleaned using 25 psi water pressure and a nylon brush. The fragments were rejoined using 2, 400mm lengths of 16mm Austinitic Stainless Steel (BS316) and an epoxy resin. The resultant crack in the surface of the stone where the 2 halves joined was partially filled with an acrylic resin and stone dust material which was saturated sufficiently to create a cosmetically sympathetic repair. The stone was photographed and made ready for its return to Govan.

[ Plate 6 ]
Plate 6: No. 36 ( frags 1, 3 )

The 4 individual stones were returned to Govan Old Parish Church on 8/9 February 1994.

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