Fragment: a focal point, in focus

Fragment (1956-59): Initial Investigations and Conservation Objectives

frag 1

Fragment before conservation, seen in transmitted light.

 History and Description:

Bold, robust and distinctive, Fragment is a stand out piece of Clarke’s early open-cast abstract relief work in aluminium and glass.  The piece was cast in shape with multiple elements used to create a deep impression into a bed of sand, with molten metal poured into the mould in order to form the peculiar aluminium frame structure and protruding tubes.

frag 2

This image shows the complex sculptural composition of the piece. The upper green piece of glass is loose and requires stabilising. The adhered lead has a layer of corrosion product forming.

The sweeping blocks of layered glass inserts combine harmoniously with the dense metal composite, enticing the viewer to look more closely at how the piece was made.  Fragment is characteristic of Clarke’s work of this period, in being imbued with religious and symbolic imagery.  The work was created by request of Hugh Casson, architect and interior designer, to provide a focal point to a room setting ‘instead of a fireplace’, and was intended to form part of Flat ’56, an exhibition of wallpapers and fabrics early that year.[1]

In the development of Clarke’s works in glass, Fragment represents an important stage between his mosaics (1949-55) and fully three dimensional works in aluminium and glass for Ipswich Civic College (1961), Crownhill Parish Church (1961), Taunton Crematorium (1963) and Manchester College of Art (1969).  Following the damage and subsequent disappearance of companion sculptural piece Embryo, Fragment now constitutes the sole surviving example of Clarke’s work in aluminium and glass in this style.

Fragment was one of six pieces that Clarke presented in the ‘British Artist Craftsman’ exhibition organised by the Smithsonian Institute, which toured the United States of America in 1959-60.  It was toured again and exhibited in ‘The Pleasures of Peace’ exhibition at the Sainsbury Centre for Visual Arts, UEA, Norwich, in 1999.


After initial research, a closer investigation into the piece’s current condition was undertaken.  A detailed observation highlighted areas of the piece that may require focused conservation treatment.  This analysis formed the basis for a condition report and conservation proposal.

Overall, the piece is in a relatively good and stable condition, particularly considering the endurance of physical stresses and changing environmental conditions after extensive touring.  It appears that the panel has encountered no previous restorations or repair work, thus the pieces is entirely original and of the artist’s intention.

frag 3

A magnified image of the lead carbonate blooming on the surface.

Whilst structurally sound, there are a number of key features to address with regards to conservation treatment.  Firstly, there are two pieces of glass on the interior surface that are loose and becoming detached from their original setting.  Without intervention these pieces could weaken further and become damaged or lost, impacting upon the integrity of the composition. Secondly, the aluminium frame and adhered lead strips show early signs of a corrosion product forming that could cause the metal elements to deteriorate further if left untreated. Thirdly, dirt and dust particles have become caught in-between some layers of glass.  As well as having a detrimental visual effect, this may cause microbiological growth that could impact upon the future preservation of the piece.  The conservation effort will be key in increasing the longevity of the artwork, as well as ensuring that it is displayed as intended, to intrigue and fascinate the onlooker.

Preparing for Conservation:

Fragment is due to be treated at the York Glazier’s Trust studio within the next few weeks.  The conservation approach will support the future preservation and maintain the artistic integrity of the piece.  The next blogpost for Fragment will detail the methodology and process of conservation at each stage of the process, providing an insight into contemporary conservation approach and practice.

Tom Vowden

[1] LeGrove, J. Towards Retreat: Modernism, Craftsmanship and Spirituality in the work of Geoffrey Clarke. Doctorate. University of Derby 2007:p. 130.


‘Priest’ – Part 1: An evaluation of the materials used in the construction of a Geoffrey Clarke panel, and an analysis of their condition.

History and Description

'Priest' (1949) - Interior view

‘Priest’ (1949) – Interior view

Of all the panels, Priest is certainly the most fragile. Like St. Sebastian, this panel was created in 1949 during Clarke’s time as a student at the Royal College of Art in London. It is very experimental by nature, and utilises a number of different materials in its construction, including wood, plaster and glass.

The panel shows the bust of a figure against a darker background. It may be assumed from the name of the piece that this figure is a Priest, and his hands look as though they are about to join in a praying gesture. His hair is blonde and chin length, and his eyes, which face directly towards the viewer, are a piercing blue, and appear to follow you around the room. The panel is set into a wooden frame, and rather than being a stained glass window in the traditional sense, in this panel the lead has been substituted for plaster, and the intervening spaces filled with mosaic pieces of glass.

'Priest' (1949) - External view

‘Priest’ (1949) – External view

The process in which this panel was made began with the painting of a rough design on a piece of clear glass with black paint. This was then turned over, and plaster was applied onto the surface of the glass, following the lines of the painted design. Pieces of coloured glass were then set into this plaster while it was still wet, and more plaster was built up around it, a process that was repeated in areas so numerous layers of glass were embedded in one place. Once dry, the an additional layer of mortar was applied from the front, and was painted a dark grey, so there was more contrast between the glass and the ‘lead’ substitute. This process has created a form of mosaic, similar to dalle de verre windows, but on a much smaller scale. Dalle de verre is the technique of setting large blocks of coloured glass into a concrete surround, a process which was in use around the time Clarke was making Priest, though he apparently never did make large scale versions of this method using concrete himself.

The Condition of the Panel

The interior of the panel viewed from an angle, note the 3D plaster

The interior of the panel viewed from an angle, note the 3D plaster

There are a number of problems with this panel and it is incredibly unstable, due to the nature of the materials used and the manner in which they have been applied.

In order to formulate a conservation proposal, it is necessary to first assess the condition of the panel, and to identify where the issues lie. The rest of this blog post will be divided into sections that describe each of the materials used, and discuss their condition. A condition report can also help identify if there have been any previous attempts to repair or restore a panel, which can be valuable when there is no written documentation about this available.


There are two types of glass used within Priest. The first is the backing plate, measuring 545mm (h) x 390mm (w) x 2mm (d). This is made of horticultural glass, the kind you may recognise from greenhouses. This is even in texture, and clear with a slight tint of green. This is why you may hear clear glass referred to as ‘tint’ glass – if you look at it from the side, you will see that there is a green hue to the material, though it may appear perfectly clear from the front.


  • Dusty inside and out
  • A large semi-circular crack is in the lower left hand corner (when viewed from the reverse of the panel).
Detail of the break in the glass backing plate (exterior)

Detail of the break in the glass backing plate (exterior of panel)

The second type of glass used in this panel is the various coloured pieces set into the plaster. The glass is of a variety of different colours, with purple, yellow, blue, red, turquoise and rose among the most prominent. These pieces of glass are relatively thin, and appear to be machine-made, due to their very flat surfaces and even thickness. There are a few pieces which are what we would call ‘antique’ glass. Later in his career, Clarke was fond of using this traditionally made ‘mouth blown’ glass from the Hartley Wood and Co. glasshouse in Sunderland. Mouth blown, or antique glass is still made today, and is often favoured during the conservation work of medieval glass, as it can be made to match the original very well. This can be identified as having more character than machine-made glass, with more irregularities in its thickness and discrepancies in its texture.

Interior of the panel, areas where the glass has fallen away from the plaster are illuminated by the light shining through from behind

Areas where the glass has fallen away from the plaster are illuminated by the light shining through from behind (interior of panel)


  • Some pieces of glass have become detached from the plaster and have fallen down and become lodged between the plaster and the backing plate, leaving holes in the design.
  • Some more pieces of glass have become loose, and can be seen hanging from their plaster surround.
  • Dusty inside and out.
A piece of glass barely attached to the plaster (exterior)

A piece of glass barely attached to the plaster (exterior of panel)



The plaster used in this panel is a light cream colour when viewed from the reverse. From the front, this has been ‘painted’ with a viscous concrete or plaster mixture to darken it. There are some areas where a lighter grey and a more yellow-toned substance have been used to stabilise the plaster network, which shows that there have been at least two separate attempts to repair the plasterwork in the past, judging by the different approaches to the choice of repair material.

Cracking in the plaster (exterior)

Cracking in the plaster (exterior of panel)


  • The plaster is cracked, especially around the nose of the figure.
  • On the left hand side of the face, some of the plaster has fallen away.
  • Dusty inside and out.
  • The yellow-toned material added around the nose area has lost its adhesion to the original plaster, and is visibly loose.
  • From the reverse, where pieces of glass have fallen away, there are remnants of an adhesive, which have been applied to hold the glass in place, but have failed. This may be evidence of a repair made after the piece was constructed.
  • Around the backing plate, sections of plaster have crumbled and become loose.
  • The whole of the plaster structure is bowing out towards the front – away from the backing plate that it was originally stuck to – due to its weight.
Evidence of earlier repair to the plaster (interior)

The areas surrounding the nose is evidence of an earlier repair to the plaster, and has become loose (interior of panel)

Remains of silicone on the glass and plaster (exterior of panel) - also note the dust on the surface of the glass

Remains of adhesive on the glass and plaster (exterior of panel) – also note the dust on the surface of the glass


The frame surrounding the panel is made from wood painted a dark grey shade, and comprises of a thicker surround with a thinner wooden beading inside – which is visible from the front. Only visible from the reverse of the panel is a smaller frame that the backing plate is attached to with plaster.


  • Generally in good condition.
  • Inner beading has become loose in areas.
  • Cobwebs and dust over reverse of the frame.
  • When stood on lower edge, the panel does rock slightly.
  • Some of the frame is scuffed along the front.


The black paint lines on the exterior of the backing plate are applied in relatively thick strokes, but in a somewhat ‘sketchy’ manner. This paint is referred to as a ’cold paint’ as it has not been fired to the glass, as common in more traditional painting methods used in stained glass.

'Priest’ (exterior of panel) from an angle; note the area where the paint has been lost, in contrast to the more defined black paint

‘Priest’ (exterior of panel) from an angle; note the central area where the paint has been lost, in contrast to the more defined black paint surrounding it


The consistency of the paint is powdery and therefore is unstable.

There is an area where a proportion of the paint has been lost, though a ‘ghost’ or trace of the paint is still visible in certain light.

Additional Materials

The backing plate is held in position with nails, packed underneath with small off-cuts of an engineered wood. On the reverse of the panel, thin black card or sugar paper was originally attached in strips to each side of the frame with nails. This was done to block out the light when viewed from the front. An eyelet is screwed into each side of the frame and a length of picture framing string is attached.


  • The string has weakened with age and so could no longer be relied upon to hang the heavy panel.
  • All of the nails are very rusty.
  • Some of the black paper is missing from the reverse of the panel and so light is let through, which is disruptive.
  • The pieces of wood used to hold the backing plate in place are dusty and loose.
Priest 11

Wood and nails used to help secure the glass backing plate in position (exterior of panel)

To Be Continued…

Part two of this blog post will discuss the proposal made for the conservation of this panel. It will take each of the concerns highlighted in this condition report and propose a solution. The main aim of this proposal will be to stabilise the panel, as its fragility is currently a concern, and will limit it’s longevity, options for display and for its storage if left in its current state.

 Merlyn Griffiths

Seduced by St Sebastian (1949)

Maxine cleaning St Sebastian in the studio at YGT.

Maxine cleaning St Sebastian in the studio at YGT.

Part I: Initial analysis of St Sebastian (1949)

Made in 1949 whilst Clarke was a student at The Royal College of Art, this early experimental piece takes traditional stained and leaded glass and reinvents it as a sculptural medium.  The artwork combines Clarke’s considerable emerging skills as a stained glass artist and the three-dimensional thinking of the sculptor. I was introduced to the piece whilst on placement at the YGT studios this summer.  Although on first viewing I was not immediately taken with the object, I was soon seduced by St Sebastian’s quiet charm.

The first stage of any conservation is assessing the current condition of the piece and trying to determine what its original condition may have been. In the case of St Sebastian, it is known that Geoffrey Clarke liked to use ‘found’ materials in his work and preferred his pieces to appear aged. 

The construction of the piece is intentionally crude and in particular, the frame is roughly assembled.  However the surprise is the beautifully painted and leaded glass, constructed in the traditional manner, which is sandwiched between roughly cut muff glass. These thick, green tinted pieces obscure this central panel giving it a mysterious and dark feel. 


The loose piece of the wooden frame, showing residues of the glue used by Clarke.

The condition of the piece is generally good considering its basic construction.  The frame is sound except for one piece, which has become detached.  Fortunately this piece remains and reattaching it will be a very straightforward procedure.  There is a build-up of dust on the wooden surround, which will be gently removed with soft brushes. The putty holding the glass layers in place is cracked and weakened in places but as these layers are also supported by a series of panel pins, this is not too much of a concern.  Replacing the putty is not necessary and, indeed, on the reverse of the piece there are modelling marks, which are very likely Clarke’s own thumbprints. These are an important part of the piece and should not be lost.


Cleaning the panel with soft brushes.

The glass surfaces are a little greasy but there is no evidence that there has been any ingress between the layers.  A simple cleaning with a 50:50 mixture of ethanol and deionised water should be enough to improve the appearance and passage of light through the glass.

The condition of the piece is recorded fully in written and photographic form before any conservation work can begin.  A conservation proposal is then given to the artwork’s custodian who must agree to the work.

Part II: Conservation of St Sebastian (1949)


Removing dirt from the wooden frame using a small brush.

The conservation began with the cleaning of the wooden surround.  This was undertaken with a series of soft brushes.  It was surprising how much material was lodged between various parts of the frame.  The appearance of the piece was considerably improved by this simple treatment.

The glass cleaning proved more problematic especially the surface on the reverse of the piece.  After a 50:50 mixture of ethanol and deionised water proved somewhat ineffective in removing surface grease, a neat solution of ethanol was used.  This was more effective but not completely successful and so acetone was applied.  Again, there was some improvement, however a number of stubborn areas of greasy film remained on the surface of the glass. As the muff glass pieces are so ‘glassy’ and could not be harmed by a treatment with white spirit, this was the final cleaning option.  Cotton wool pads soaked in white spirit were applied to the rear surface and left for several minutes.  These were then removed and the greasy residue was treated with a scalpel.  Even this approach was not entirely successful, and a few faint traces remained.  These residual marks in no way impede the passage of light through the piece, nor do they threaten the glass surface in any way.  This being the case, further treatment was not considered necessary. The position of the marks were recorded in the treatment report for future reference.


Removing the original glue with a scalpel.

Reattaching the detached piece of wooden frame was a straightforward procedure.  First the failed adhesive was removed from both surfaces with a scalpel.  This was very easy, as the yellowed glue was flaky and loose.  A quick wipe with a cotton bud in warm water removed any remaining residue.  New adhesive was then applied and the piece positioned and held until the glue had ‘gone off’.  The original adhesive used by Clarke was an animal or ‘hide’ glue which had failed over time.  It is usual practice for conservators to replace ‘like with like’ when restoring an object, however it seemed imprudent to used a substance which had already proved inadequate in the artwork’s lifetime.  For this reason, polyvinyl acetate or PVA was used as a superior alternative.  This glue is highly recommended by conservators of wood, bone, ivory, textiles and ceramics because of its reversibility.

The conservation of the panel is now complete and St Sebastian has been kitted out with a custom transportation and storage box which will keep this important piece in excellent condition whenever it is not on display at The Stained Glass Museum.

Maxine Allen

Welcome to our blog!

Welcome to our blog, documenting the conservation of four modern stained glass panels by Geoffrey Clarke (b.1924) recently purchased by The Stained Glass Museum, Ely. The conservation of these panels will help preserve them for the future.

It is hoped that through documenting the conservation of these stained glass panels at York Glazier’s Trust (YGT), we will learn more about the materials and techniques used by Clarke and discuss current approaches to stained glass conservation. We will also discuss the challenges of displaying these artworks as we prepare to put them on display in our main gallery.

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