Glass Opus Sectile War Memorial

St. James’ Church, Mill Lane, West Derby, Liverpool, was designed by Edward Welch 1846. Glass Opus Sectile war memorials are particularly rare. Out of nearly 60,000 entries on the United Kingdom National Inventory of War Memorials, less than 20 are listed. Unfortunately, there is very scarce information about the St. James’ memorial and its commissioning. The only record that exists is a brief and tenuous entry in the parish records of mid-1920’s, where interest in dedicating a stained-glass window to the deceased is noted. Liverpool City Library, members of the local community, Whitefriars archives at the Museum of London and the Victoria and Albert Museum, and an expert in James Powell & Sons’ Ltd Opus Sectile were consulted with regards to provenance; unfortunately, the maker of this unique mosaic remains unknown.

The memorial is sited centrally on the east wall of the south transept. It is comprised of a mosaic glass panel and sandstone surround. The mosaic is a combination of Opus Sectile, smalti and reverse-gilded glass, which totals just less than 3000 pieces. Non-decorated, coloured glass is rippled, whereas the Opus Sectile is decorated with fired enamels and has an egg-shell finish. Originally, all glass was embedded into lime mortar on wooden backboards. The main focus of the mosaic design is a monument that lists 18 local servicemen of World War I, which is flanked by a soldier and a sailor. Shields with ensigns of the Merchant Navy, the Royal Navy and the Royal Standard are represented, as too is the emblem and motto of the Royal Flying Corps, Per Ardua ad Astra (Through Difficulties to the Stars). There is a fine image of the Lusitania (Cunard Liner) to the lower section of the panel, below which there is a dedication to those who lost their lives. The sandstone frame is composed of 6 sections; the bottom panel lists 35 local servicemen of World War II.

Causes of Deterioration 

Water ingress to the east wall of the south transept promoted excessive damage and deterioration to the whole monument, particularly to the glass element.  The wooden backboards on which the glass had been mounted had become swollen and distorted, causing breakages, detachment and several losses. A report on Phase 1 documented that the sandstone surround had suffered from corrosion and failure of its metal fittings. There were other causes of deterioration related to the building envelope in the area above the location of the monument; dry rot was discovered and required treating in preparation for the return of the monument.

On acceptance by EDGE the mosaic had already been removed from situ and faced-up (Phase 1) with Japanese Tissue. This temporary protective skin retained the glass, keeping it in its original position . Several glass pieces had become detached before the panel was faced-up and these had been stored separately.


To facilitate safe transportation from the church to the studio and to reduce the risk of further detachment of the glass, the panel was wrapped in Clingfilm. It was also cushioned with a layer of Plastazote foam and travelled flat.

 Removal of Japanese Tissue.

At this stage, the exact structural stability of the glass and solubility of the surface decoration was unknown. To enable a full assessment, it was decided to remove the tissue, and this was done initially with a scalpel blade . As each section of glass was uncovered, a visual assessment was made. The various types of glass and      decoration were also spot tested. Residual adhesive from the tissue was removed with acetone swabs. Once revealed, it was clear that the mosaic was in poor structural condition. Not only were the backboards extremely distorted but they had split in several areas. This resulted in partial and complete detachment of the glass from its substrate . 23 pieces of glass were broken into 2 -10 fragments. Also, most of the gilding no longer remained attached to the back of almost 300 pieces of glass but was adhered to the mortar; a result of water ingress and the pulling action of the backboards

Mapping Out

It was vital that the position of every piece of glass was recorded to ensure it returned to its correct position when re-mounted.  This was done by mapping out and digital photography. To facilitate the tracking of each piece of glass throughout its treatment the panel was delineated into a grid of 18 sections; three columns A -C and six rows 1-6.  Small tabs of Magic Tape were fixed to the surface of each piece of glass and then numbered on the tape; referencing their section and number within that section e.g. A1/123. A sheet of Melinex was then placed on top of the panel. The number and outline of every piece of glass and missing sections were traced onto the Melinex in permanent ink. As the panel was so badly warped, sandbags were used to flatten out the Melinex as the tracing progressed from the top to bottom of the panel .  Once the tracing was complete, the Melinex was cut into 18 sections that corresponded to the grid map and these were then photocopied.

Removal of the Glass from its Substrate

Several pieces of glass were easily removed as they had become completely detached from the substrate. Those that remained adhered were removed mechanically. This was done starting with the outermost pieces; the putty between the glass was cut away and the mortar below carefully removed with a scalpel blade; a scalpel blade or a  thin stainless steel dental tool was then inserted behind the glass and gentle leverage applied for safe removal. As each piece was removed it was placed directly onto its corresponding photocopy, which itself was placed on a layer of Plastazote and then placed in a stacking tray.

 Original Design and Construction Revealed.

Once all glass had been removed, several exciting discoveries were made.  Firstly, pencil outlines forming the figurative and architectural elements of the design were evident on top of the mortar, which had been applied over eight 4mm -depth wooden boards that ran horizontally. Secondly, translucent glass had been mounted on top of different coloured mortars, presumably to enhance and add further depth of colour. Thirdly, the eight wooden boards had been positioned on top of another four layers of wood; three of these were comprised of small sections that had been stitched together end-to-end, but not edge-to-edge. Each layer of wood ran at 90 degrees to the other.Several large screws remained, which connected the wooden layers and protruded beyond the bottom layer of wood. These findings provided evidence that the panel was fixed to the brick face and the glass mounted in-situ. There was no adhesive between each wooden layer; however there were excessive amounts of dust and dirt. Each layer of wood was vacuumed, recorded onto Melinex, removed, wrapped in acid free tissue and then stored.

Cleaning the Glass.

Excess mortar was removed with a scalpel blade and any residual mortar or dirt removed with the gentle application of a suitable grades of sanding fabric; using grades that did not abrade the glass.


 Almost 300 pieces of glass required re-gilding. Firstly, the glass was tacked face down to a glazed ceramic tile with wax. The tile was then propped at an appropriate angle and gelatine size applied by brush over the back of the glass, which was then gilded with 23.5 ct gold leaf.  When dry, the gilding was protected with a layer of imitation gold colour sign writer’s enamel, which also enhanced the colour of the gilding . Finally, a thin coat of epoxy was brushed over the dried enamel.


23 broken sections of glass were bonded by capillary action with a water white epoxy adhesive.

Filling Missing Areas

Small missing areas to the repaired join lines were filled and refined with a scalpel blade and various grades of sanding fabric and then retouched with a clear acrlic glaze and artist’s dry powder pigments.        


The criteria for re-mounting was that the glass panel could be easily removed if necessary and the materials used to be suitable for the unpredictable and uncontrolled environmental conditions of the church.

Choice of Backboard

The backboard used was a honeycomb core aluminium material bonded between skins of woven glass cloth impregnated with epoxy adhesive. This provided excellent backing to corrosive atmospheres and acted as an insulator between the glass mosaic and the brick wall.

Transferring the Layout of the Mosaic to the New Backboard

The transferral of the design to the backboard had to be accurate and clear; there was little margin for error. Several options were considered, including transferral using the pouncing technique or carbon paper. The chosen method was to overlay the 18 Melinex maps with Spider Tissue and trace the design onto these in pencil; but omit the reference numbers of each piece of glass.  The Melinex maps were then joined together to re-form the whole plan and this was placed on top of the new backboard.  From this, the layout was marked up in pencil around the edges of the backboard so that the Japanese tissue tracings could be accurately placed. The Melinex was then removed and the tissue tracings permanently adhered to the backboard

Retouching the Plan in Preparation for Re-mounting the Glass

Referring to the original wooden boards that supported the glass, acrylic paints were painted onto the new backboard to mimic the colour of the mortar that had lain behind the translucent pieces of glass.

Re-Mounting the Glass

The backs and edges of each piece of glass were swabbed with acetone and then bonded to the backboard with an acrylic adhesive; working from the bottom – up . The adhesive was applied to both the back of the glass and its corresponding location on the backboard. Throughout the mounting process the layout was regularly checked with straight edges and setsquares to ensure that all architectural, figurative and textual areas of the design ran true .

Replicating Missing Areas

Once mounting was complete, three areas of loss were identified: the shield bearing the ensign of the Merchant Navy (evident from an archived photograph) and a missing piece from the sunbeam and the leg of the soldier. Other than a predominance of red rather than white, the design of the Merchant Navy shield had the same layout as that of the Royal Navy. The Royal Navy shield was therefore used to form a template for replication. Due to its size, it was decided to not cast the replica shield in a resin but to cut it from an appropriate thickness of white opaque glass. The decoration was then painted with a signwriter’s enamel paint. The other missing areas were cast, away from the panel in epoxy. The sunbeam cast was tinted with artists’ dry powder pigments to mimic the colour of the original glass and before epoxy had cured, when it was ‘just’ tacky, this cast was gilded on the reverse with 23.5ct gold leaf. The cast area from the leg of the soldier was retouched with a clear acrylic glaze and artists’ dry powder pigments. All replicated areas were adhered to the backboard as previously detailed.

Application of Putty between the Glass

The putty used was a butyl non-setting glazing compound. Although non-setting, it does form a firm skin over time. This was pushed into the gaps between each piece of glass by hand and with wooden pottery tools. After 24 hours, soft non – peppering tissue was gently passed over the surface of the glass to remove excess putty and to give the glass a final surface clean. The putty was finally smoothed by hand.

Return to St. James Church & Re-instatement

Phase 2 was completed by EDGE and the glass panel returned, along with its original backboards, to St. James Church.

The re-instatement of the memorial, with its sandstone surround was undertaken by another company who specialise is stone conservation. However, as the stone surround and glass mosaic panel were intrinsically related, structurally, and physically, it was important to maintain close liaison with all parties to facilitate the smooth and safe reinstatement of all elements. As such EDGE informed the installation strategy and maintained contact throughout installation.

An ‘official’ unveiling ceremony took place on Armistice Day. To the delight of the congregation of St James and the local community, the story of the memorial was covered in the local press, by BBC radio and in church publications.