Plaster Render & Decorative Surfaces     

St Martin’s Chapel, Chisbury, Wiltshire.             

Architect: Philip Hughes Associates, Wincanton.
Client: English Heritage, SW Region.
Repair and conservation of the original plaster and render of this 13^th Century Chapel. Grout was used to stabilise the severely laminating and blistering surface.  An adhesive mix was used to reset loose sections, pack large cavities and consolidate weak and friable edges.   Render repair mix was used as a buffer zone to protect the original render and pointing mix was used to rebed loose flints and stones and rebuild the NE corner, colour washed to match.  

The projects from the treatment of plaster can vary from remnants of medieval decoration to extensive narrative schemes from the nineteenth century. This spans a huge range of original materials and techniques and a similarly complex and flexible response.

Other examples - Tintern Abbey. Monmouthshire. Studely House, Wanstow, Somerset. Roman Baths, Bath. The Great Chapel, Bishop's Palace, St David's.

St Mary's Church, Llanfair Kilgeddin, Monmouth. The Sgraffito Murals by Heywood Sumner.  1888-1890.  Preliminary trial studies                    

Conservation Programme to, “ O Ye Beasts and Cattle “

This extraordinary decorative scheme was executed in the sgraffito technique by Heywood Sumner.  He was a distinguished figure in the continued regeneration of the decorative arts in England at the turn of the century and a central figure in the Arts and Crafts Movement.  The murals illustrate the hymn of creation in praise of God, 'The Benedicte' which gave the artist the opportunity to explore different types of picture making.

The sgraffito technique involved putting three coats of plaster on the wall.  First a rough coat to form a base, then a colour coat and finally a fine surface coat out of which designs were cut to reveal the colours below.

Early in 1998 Strachey and Strachey was commissioned to carry out a condition and strategy report for The Friends of Friendless Churches. In this report we recommended that the conservation of one  panel should precede any major programme of works to both explore appropriate techniques and materials, and to begin to establish an overall idea of time and cost. In February and March 2001 work was carried out to the above panel.  

The panel, 'O Ye Beasts and Cattle' exhibited all the main causes of damage and decay to the murals.  These included water penetration from the roof and rising damp, structural movement causing major cracking to some panels, the system of materials used by Sumner in relation to the original fabric, the presence of bats and a general fogging of the colour coat.  Our main aims now that the mural’s environment had been improved was to alleviate the stress on the murals of the constant rising damp and to attempt to reinstate a bond between Sumner’s hard cement render and it’s softer neighbours.  We also needed to look at methods to clean off the white deposits to reveal the richness of the colours beneath and to repair the damaged areas.

The hard cement render of the dado beneath the panels was removed and replaced with a more porous lime mortar render to facilitate the exit of moisture and salts below the sgraffito panels.

The stabilising of the extensive areas of loose render was achieved in a number of ways.

Firstly, grouting with hydraulic lime, which has an affinity with the surface coat and OPC, which is matched with the coarse coat and all the colour coat mixes except for the black.  We also made some tests grouting with dispersed lime, which proved to have a good flow and set.  Secondly by making points of attachment with ceramic pins secured with hydraulic lime to the softer plaster behind Sumner’s cement coarse coat.  This proved to be a simple and effective method of attachment, which did not soak the fragile internal structure of the sgraffito by grouting.  Thirdly loose areas were detached and refixed with a lime based adhesive mortar similar to the one used to fill the main cracks through the panel.

Repairs to the colour coat and surface coat were made to lost detail which required us to develop some skill in the sgraffito technique as well as using a surface coat mix to fill the maze of fine surface cracks.

The most successful method of cleaning the surface of the murals was with Wishab Dry Cleaning Sponges which are neutral PH sponges designed for the safe dry cleaning of this and related surfaces.

 The presence of the bat colony continues to be monitored and contact has been made with the Bat Conservation Trust in the Gwent area.