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Case Study
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Case StudyProject: Iznik Chimney
We were commissioned to remove, conserve and remount the Iznik ceramic tiled fireplace situated in the corridor adjacent to Gallery 33. The fireplace was to form part of a touring exhibition of Islamic artefacts, so it was essential to design and construct a lightweight, demountable structure to support the exhibit. The fireplace had previously been relocated within the museum building on the 5th October 1987. Unfortunately, virtually no documentation existed for this project. Enquires revealed the estimated weight of the fireplace to be 1½ tons and very top heavy. It had been set into a niche with approximately two inches clearance around the outer edge, held in position with folding wooden wedges, wire mesh and plaster infill. (Images 1, 2, 3,4 & 5)
Removal
A polythene screen was erected around the outer edge of the fireplace tiles, to contain the dust and protect the museum environment during de-installation. An adjacent ventilation grill was covered to prevent dust penetration. Photographs and dimensions were taken of the fireplace prior to the application of two inch gum tapeacross the decorative glazed surfaces of the tiles. (Image 6) The tape protected the tiles during the removal process and subsequent transit to the workshop. Two continuous cuts were made, 60mm apart all around the outer edge of the fireplace tiles. The masonry and plaster infill was then carefully chased out with hand tools and folding wedges inserted to hold the fireplace in position. (Image 7 & 8) A 12mm diameter hole was drilled in the masonry above the fireplace and a 12mm expanding eyebolt was inserted into the hole to enable the fireplace to be supported by a rope as it was lowered to the ground. (Image 9 & 10) The wooden plinth surrounding the marble hearthstone was removed to investigate the underlying structure. The hearthstone was lifted out, with a hydraulic pallet truck inserted underneath it. This incidentally reduced the weight of the fireplace by approximately 6cwt. An A frame gantry with locking wheels, suitably paddedwith foam was positioned in front of the fireplace to prevent the top heavy structure falling forwards. The pallet truck was inserted through the hearth opening and positionedcentrally, to lift the fireplace in its entirety. The folding wedges were removed, and the fireplace lifted vertically and pulled approximately one foot forward out of the niche. (Image 11 & 12) It was now possible to secure the rope to a large wooden cross member, (Image 13) which formed part of the fireplace backing structure, and pass it through the eyebolt secured in the masonry above the fireplace. The fireplace was then extracted from the niche a further two feet, allowing access to inspect the main structure and re-secure the rope.
Two timber planks were placed behind the chimney at 60 degrees to the horizontal,, the tension was taken up on the rope and the pallet truck, supporting all the weight, pulled the fireplace carefully out of the niche. Thus allowing the top of the fireplace to lean backwards onto the planks. The strain was taken up on the rope and gradually the fireplace was lowered safely into the horizontal position. (Image 14, 15 & 16) Two large rectangular angle iron frames with nylon swivel castors were positioned beneath the fireplace and the whole structure was pushed into the adjacent gallery. (Image 17, 18 & 19)
Deconstruction The fireplace in its present form was too large to move through any exits at the V&A. It was therefore necessary to partially dismantle the fireplace. The gum tape was removedand identification labels were attached to individual tiles. (Image 20 & 21) A 22mmdiameter x 0.5mm thick circular diamond saw was used to cut through the grout joints, isolating each tile. (Image 22, 23 & 24) The tiles could now be gently prized from their fixing bed (Image 25, 26 & 27) and the underlying exposed timber framework cut away, leaving the cone and canopy superstructure intact. (Image 28, 29, 30, 31 & 32) The individual tiles were placed into custom made wooden boxes, packaged with bubble wrap and straw. With the outer tiles removed, the chimney was much reduced in size, enabling the upper and lower canopy to pass through double doors, up ramps and onto a trailer to transport to the workshop.
In the workshop, tracings were taken of the canopy (Image 33) and two plywood templates were constructed around the upper and lower canopy to replicate the complex angles and contours of the original tiles. (Image 34, 35 & 36) This documentation was essential for accurate reconstruction, as the dimensions of the canopy varied and were not completely symmetrical. Deconstruction of the tiles continued, cutting between the grout lines and carefully prising the remaining tiles away from the canopy superstructure.
Restoration Following the dismantling of the fireplace, the glazed surface of each tile was cleaned with deionised water to remove dirt and residues of glue and gummed paper. Paint residues were removed with a scalpel. The tiles were then laid out in sequence, so that detailed plans of the damage could be drawn up. Although deinstallation and deconstruction of the fireplace were carried out without damage to the tilework, their condition on close inspection was quite poor. Many tiles were chipped and broken; of a total number of 152 tiles, 148 were in need of some conservation. After demounting, most of the tiles retained a 20mm thick plaster screed on their backs, which was removed due to the danger of salt migration through the tile body. The removal was carried out by first cutting away the bulk of the plaster with a 12inch circular saw, the thin layer remaining on the tile backs being removed with palette knives. Following this process may old repairs broke down: some tiles had been joined together in-situ with the fixing plaster, many had been strengthened with a plaster and hessian backing screed, some had shallow channels cut out of their backs to accommodate 3mm diameter wooden reinforcing splints secured with plaster, (Image 37) and some tiles had been reassembled with shellac, wax or animal glue. Most of the old repairs had conserved the tile work, but some had unfortunately caused staining of the tile body. (Image 38 & 39)
Repair work to the tiles began with reassembling and gluing together of broken tiles, and in some cases this required the dismantling of old misaligned repairs. Broken edges were carefully cleaned with deionised water and a soft tooth brush. More stubborn grease and dirt was removed with white spirit or acetone. Old adhesives were either picked away with a scalpel or broken down with warm water, white spirit or acetone. More vigorous solvents such as ammonia and Methylene Chloride were not utilised because of the softness and porosity of the frit ware body, and consequently it was not possible to remove all the staining from the tile bodies, most notably that caused by the use of shellac as an adhesive. Once breakages had been thoroughly cleaned a dry run was carried out without the adhesive, reassembling each tile to check for missing fragments and for correct surface alignment. (Image 40) Broken tiles were then glued together with Paraloid B72 adhesive and left to cure in a box of silver sand. (Image 43) Complex and delicate breakages were reinforced or supported during curing with masking tape stitches or plasticine. (Image 41) After curing, restoration continued with the filling of chips and holes with a putty made from Polyfilla and PVA and water mixture (ratio 10grms: 4mls). Fillings were cut back to the tile surface using Stanley blades and scalpels (Image 42) and finally rubbed down with Micromesh abrasive paper (2400 grade). (Image 44 & 45)
Retouching was undertaken using Keeps oil based glass paints, (Image 46 & 46a) thinned with pure Turpentine and glazed with Tor Life clear glaze, a two-component acrylic urethane resin cured with an aliphatic isocyanate hardener.
A solution of Paraloid B72 and Acetone was applied to the reverse of each tile, sealing the porous tile body and forming a break line, should it be necessary to reverse the relaying process in future. The tile bodies varied in thickness and it was necessary to make them all uniform for the purpose of relaying. To achieve this each tile was placed in a wooden jig and a new backing was cast with Polyfilla. (Image 49, 50, 51, 52 & 53) Tiles that had been broken were reinforced with plastic mesh and 3mm stainless steel rod. (Image 47 & 48) Each tile was now 20mm thick. A solution of Paraloid B72 and Acetone was applied to the Polyfilla tile backing where the Araldite adhesive dabs would be placed. The tiles were now ready for relaying.
Mounting The Iznik chimney was to form part of a Islamic touring exhibition, travelling extensively abroad. It was therefore necessary to create a lightweight demountable structure, consequently the fireplace was divided into 8 pieces, which all located and hung onto a large aluminium support frame, which was secured to the wall. With restoration completed, the tiles were laid out into their various panels and accurate measurements taken. (Image 55, 56, 57 & 58) At this stage, with precise measurements, it was nowpossible to draw up the support frame, which incorporated mitred hanging bars and fixing cleats. The frame was fabricated from 50mm x 50mm aluminium hollow box section. (Image 61)
The tiles were to be mounted on Hexlite Board 620, a woven glass fibre reinforced epoxy skin containing a core of Aeroweb aluminium honeycomb of 83kg/m 3 (5.4LB/ft 3) nominal density, chosen for its strength, rigidity and lightness. Each piece of Hexlite 620 was now cut to size and placed onto the aluminium frame to align and secure hanging bars. The complex shapes of the upper and lower canopy were also constructed from Hexlite 620 board. (Image 62) The mitred edges of board were bonded with Araldite 2015 resin and glass fibre matting was applied over the joints to increase strength and rigidity. (Image 63) Glass fibre matting was also applied where hanging bars were to be positioned. The tiles were now laid dry onto the Hexlite board and holes marked where adhesive would be placed. (Image 66) This precaution would facilitate reversibility if required at a later date. The tiles were removed and 5mm holes drilled through the Hexlite.
Battens were temporarily secured to the outer edges of the Hexlite board, to ensure accuracy when laying the tiles. Araldite 2015 adhesive was now mixed in the following proportions: 300gms resin A, 300 gms resin B and 300gms of grade 1.5 glass Micro Balloons and applied in dabs on precise areas of the tiles corresponding with the holes previously drilled in the Hexlite. The tiles were laid on each panel and left to cure. Each panel was grouted with Polyfilla mixed with PVA and toned down with pigment to match the background colour of the tiles. The addition of PVA would impart slight flexibility. The outer edges of the hexlite panels were filled flush with polyfilla to create a smooth finish. Plastazote foam strips 8mm thick were secured to all vulnerable edges, to provide protection during installation and demounting. Powder coated aluminium strips 104mm wide by 2mm thick were fixed to the outer edge of the panels, to protect the vulnerable tile edges. Replica Hearth The main body of the hearth, including decorative side pieces was constructed from medium density fibreboard, hollow laminated to reduce weight. In order to replicate the carved detail and mouldings, including the rope carving at the front, a plaster of Paris mould was taken from the original. (Image 67) A cast was then made in polyester resin, which was then inserted and attached to the main body of the hearth. The replicated marble finish was obtained using acrylic paints to match the original marble hearthstone, sealed and polished with beeswax polish. For maintenance purposes or cleaning a beeswax polish should be used. The curved hearth back was constructed from white Foamex board which was sprung into position from the hearth front and held in place along its two vertical edges by the aluminium protective strips, fixed to the tile panels. (Image 68) Two copper bands were fixed to the backing frame with self tapping screws, positioned behind the Foamex board at the top and the base to hold and support it.
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