Reasons for Designation
Glass has been produced in England since the Roman period, although field
evidence is scarce until the late medieval period. Wood was the main
manufacturing fuel up to the early 17th century, so the industry was located
in woodland areas, particularly the Weald. From about 1610, production shifted
to the coalfields.
Glass production requires three major components: silica, alkali and lime,
together with colouring material for certain products and decolourisers for
clear glass. Lead was also used in the production of certain types of glass
during the Roman period and after the 17th century. The manufacturing process
involves three stages, fritting, melting and annealing. Fritting was a common
practice before the 19th century involving heating the main glass constituents
to produce an unmolten material for grinding, melting and annealing. Melting
involved the remelting of previously formed glass, and the production of new
glass from raw materials. Until the late 19th century, glass was normally
melted in pre-fired crucibles of refractory clay, on stone benches called
sieges, within the melting furnace. Use of coal as the preferred fuel and
automatic bottle-making machinery in the 1880s led to changes to the melting
furnaces and the use of larger furnaces, hitherto conical structures over
circular furnaces. Regenerative furnaces were developed in the 1860s, and tank
furnaces for bulk melting quickly followed. Flat-glass production methods were
made obsolete by the Pilkington float-glass system of 1959. The third process
is annealing. Because the rapid cooling of molten glass can give rise to
internal stresses, glass was treated in furnaces designed to heat the glass to
a point where deformation begins, then cooled gradually. In the 19th century
conveyors were introduced to take glass through a hot zone into cool air.
Features on glass manufacturing sites include various types of furnaces,
producer-gas plants for the making of gas from coke at 19th century
glassworks, bottle-making machinery, blowing irons or pipes for blowing glass,
glass residues and various buildings used as stores or warehouses. A total of
135 glass production sites (representing about 25% of the estimated national
archaeological resource for the industry) have been identified as being of
national importance. This selection, compiled and assessed though a
comprehensive national survey of the glass industry, is designed to represent
the industry's chronological depth, technological breadth and regional
diversity, and to include all the better preserved glass sites, together with
rare individual component features.
The glass melting and annealing workshop which forms part of Shrigley and
Hunt's stained glass manufacturing workshops is an outstanding and unique
survival of late 19th/early 20th century in situ stained glass manufacturing
furnaces.
Details
The monument includes a glass melting and annealing workshop which formed part
of Shrigley and Hunt's stained glass manufacturing workshops. It is located in
a cellar at the rear of number 23 Castle Hill, a building which had formerly
been the main part of Shrigley and Hunt's workshops. The cellar is accessed
via an external `L'-shaped flight of stone steps which lead to the only door.
Internally the cellar is tunnel-vaulted or arched, with the concrete floor
acting as the arch's springing line, and is constructed of a combination of
sandstone and brick. An offset central timber acts as a roof support. The
cellar's south wall has a brick-built drain added to its interior while the
internally curving east and west walls are featureless. The most interesting
features are situated on the brick-faced north wall where four melting and
annealing furnaces have been built into the wall. The melting furnaces
facilitated the re-melting of previously-formed glass, the production of new
glass from raw materials, or a combination of the two activites whereby new
materials were mixed with broken glass known as cullet. The glass was melted
in crucibles placed in the furnace. The rapid cooling of molten glass gives
rise to internal stresses and deformation and, unless annealed, the glass will
readily shatter. The annealing furnaces here facilitated the process of
re-heating previously molten glass to a temperature below the point where
deformation begins. The glass was then gradually cooled thus resulting in a
considerably strengthened finished product.
The firm of Shrigley, painters and gilders, had late 18th century origins,
coming to specialise in stained glass manufacture from 1870 when A W Hunt of
London took over. The main building fronting Castle Hill has late 18th century
origins and was occupied by the firm from about 1890. It was converted to
studios and workshops in which stained glass of a very high quality was made
for the national market. The cellar housing the furnaces originally formed the
basement of a three-storey building which has now been reduced to a single
storey. Glassmaking is thought to have continued here until about the mid-20th
century. Number 23 Castle Hill, including the cellar, is a Listed Building
Grade II.
A number of features are excluded from the scheduling; these include the
electricity sub-station, the surface of the yard fronting the west side of
the building housing the cellar, a modern timber roof support in the
cellar, and a brick-lined drain on the cellar's interior south wall. The
ground beneath all these features is included as is the cellar wall behind
the brick-lined drain.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
