In search of Vitrolite
Michael Taylor tells the tale of a quest for a replacement for a pink 1930s cladding product.
Sir Charles Keene was one of the leading civic and business figures of 20th century Leicester, and served as Lord Mayor in 1953-54. Like some other wealthy people of radical persuasion, his political interests were linked to a progressive taste in architecture and design. This led him to commission Raymond McGrath, then in his early 30s, to design the Kingstone store in Belgrave Gate, Leicester. for his retail furniture business (Fig 1). Kingstone was built in 1937 and two years later McGrath built Carrygate, Keene's house at Gaulby, in the countryside to the east of Leicester.
Fig.1. The front of the Kingstone store from Belgrave Gate after completion of work
Raymond McGrath had come to England from Australia in 1926 at the age of 23. One of his interests was in the use of glass and he published Glass in Arcbitecture and Decoration also in 1937.1 In this book he described Vitrolite and its uses for external and, more particularly internal, cladding of wall surfaces. Vitrolite was a product of Pilkington Brothers at St Helens and was one of a range of glass products widely used in the 1930s and through into the 1960s for largescale cladding and for shop fascias and interiors. It also provided a hygienic wall surface for interiors such as operating theatres, and vitreous cladding products are still in use in environments such as hairdressing salons.

Vitrolite itself was produced by the addition of fluorides in the firing process to fuse the colour into the glass body. Careful temperature control was necessary at all stages in the production process to achieve the required degree of opacity. The product was produced in a range of colours and could be cut accurately to make a range of standard ashlar sizes.

Fig. 2 The pink glazed brick boundary wall at the rear (Bedford Street) of the Kingstone Store.
References
1McGrath, R: 'Glass in Architecture and Decoration' (Architectural Press, 1937; reprinted 1961)
2DNH listing description, 31 March 1995
3Dyson, C J: Structural Glass' in jester, T C (Ed) 'Twentieth Century Building Materials: History and Conservation' (US National Park Service), pp 201-205
4McKinley, R W: 'Spandrel Glass' in Jester T C (Ed) 'Twentieth Century Building Materials: History and Conservation' (US National Park Service), pp 206-211

McGrath specified the product for the Kingstone building for cladding both on the front elevation to Belgrave Gate and to the rear facing Bedford Street. The colour he chose was dull pink which was echoed in a pink glazed brick boundary wall to the loading area on Bedford Street (Fig 2). There were vertical strips of black Vitrolite at either end of the front elevation. Kingstone was listed in 1995, after the Vitrolite had been lost from the rear by alterations carried out around 1990 before listing. The listing description of 1995 notes that the building is only the second known example of curtain walling in the UK and the first without the use of intervening mullions.

The Leicestershire Records Office holds a full set of McGrath's drawings for Kingstone showing the use of Vitrolite and a change in intention between late 1935 and late 1936 from green colouring to the pink actually used. No large scale fixing details are shown on the drawings. The Vitrolite sheets were secured top and bottom by copper strips and secured back to the wall by dabs of putty. Edges were simply butted to give a clean, sheer appearance. The drawings show details of the proposed shopfront including a marquise device for reflecting natural light from above the projecting canopy into the space of the shop window.

At the time of listing in 1995, the Kingstone company were already concemed about the condition of the Vitrolite facing on the building.2 It was evident from a street-level visual inspection that a number of the pink Vitrolite panels, as well as some of the black edging strips, were irreparably broken and had areas missing.

The company were anxious about danger to the public using the footway and it was clear that decisions had to be made about the repair of the curtain walling. There was also widespread rusting and deflection of the metal win~ dows. The company engaged J M Chamberlain and Son, builders of Leicester Forest East, and a dialogue with the City Council began about the options for repair.

An initial idea to replace all the pink Vitrolite with an ICI Perspex product was soon replaced by a proposal to salvage and reuse as much of the Vitrolite as possible and to find a suitable replacement material to make up the shortfall. It was hoped at this stage to identify a modem source of pink Vitrolite or an equivalent vitreous material. From the street it was clear that up to 12 of the 70 pink Vitrolite panels had parts missing. It was due to the care exercised by Chamberlains that the eventual total number of sheets lost was as low as 14.

The City Council undertook to try to source a replacement material and an initial enquiry to the East Midlands Team at English Heritage set in train a fascinating if frustrating process of telephone investigation. Susan Macdonald, then of the Architectural Conservation Team, responded with a compendium of information about Vitrolite and similar glass products under various trade names in the USA and Britain. Some of the American examples were used to produce spectacular examples of smooth Moderne design, sometimes with a streamlined, curvilinear theme. Fascinating, and useful though this information was, a source of a suitable material still had to be found .3,4

The Twentieth Century Society also offered valuable advice and the search led the Council's Conservation Officer through the range of modern Pilkington products, the Pilkington museum at St Helens, Norman and Underwood, and various suppliers of vitreous products. The Twentieth Century Society recommended Adrian Hewitt of Londonbased Mo Deco who said that he dreamed of finding a supply of pink Vitrolite forgotten at the back of a warehouse somewhere, but alas the dream was so far unfulfilled. Suppliers of materials to hairdressing salons were suggested and tried. John Winter was contacted and gave enthusiastic moral support but knew of no modern supply of pink Vitrolite.

Vitreous cladding materials are available in a limited range of colours including black, opal and pale green. A suitable product is made, for example, in the Czech Republic and imported by a limited range of British suppliers. But all enquiries stalled on ... you want what
colour? For anyone faced with a similar problem, Rankins Glass Co Ltd of 24 Pearson Street, London E2 8JD, or T &W Ide of Glasshouse Fields, London E1W 3JA, would be reasonable first stops but probably not for pink Vitrolite.

So an application for listed building consent was submitted and decision time arrived. The specification involved the replacement of the steel window frames throughout exactly like for like. Polished glass fibre was proposed to replace the irreparable Vitrolite panels. The existing panels were carefully removed and stored, each one being numbered for replacement in its exact previous position. The method of fixing using copper strips and putty dabs was to be replicated as the panels were reinstated. The substitute panels were placed in the spaces left by the lost Vitrolite. Black Vitrolite strips to the edge of the facade were replaced in a modem black vitreous material. A condition on the listed building consent required the safe storage of the fragments of Vitrolite not replaced on the facade.

Much depended on the quality of the replacement material and in terms of colour match and surface polish the glass fibre, made by Premier Glass Fibre Moulders of Oadby, Leicester, was remarkably close to the Vitrolite. The glass fibre panels were also made to the same thickness as the Vitrolite. The weathering qualities of the glass fibre remain to be tested in use. Certainly it is more susceptible to scratching through surface impact than Vitrolite and ladders put up for cleaning could be a problem.

In the end the result was visually convincing (Fig 1 shows the cladding after repair) and 80% of the original material was reused. Perhaps by the middle of the 21st century fashions in building materials will have changed again and a pink vitreous cladding material will be available for the next round of repair of a remarkable 20th century building.

Michael Taylor was, until February 2000, Senior Building Conservation Officer in the Urban Design Group at Leicester City Council. He is now Historic Areas Adviser with English Heritage West Midlands.
Context 65 March 2000