Details

The monument includes below ground remains of a 17th century glassworks and
18th century pottery. It is located on the east bank of Silkstone Beck in an
area now occupied by a garden centre. The monument was the subject of limited
excavation in 2002, which revealed evidence of significant surviving remains
of glass production.

The monument is in the shape of a rectangular box measuring 30m east to west
by 15m north to south with the northern side defined by the northern boundary
of the property. At the eastern side the monument is defined by the terrace
supporting a greenhouse and at the south eastern side the monument is overlain
by the corner of a modern greenhouse and an access ramp.

The site was formerly occupied by a late 18th century rectangular stone
building, thought to be associated with the pottery. This structure was
mostly levelled in 2003 and only a small lean-to and part of the northern
rear wall survive.

The production and manufacture of glass developed in Yorkshire in the 17th
century following the change from wood to coal as a fuel source. Glass
production started at Silkstone in the 1650s when the glass making Pilmay
family moved there from Manchester. The Pilmay's were a French family
skilled in glass working who along with other foreign specialists, had
been brought to England in the 16th century. In 1698 a probate inventory
lists two separate glasshouses at Silkstone, a `green house' for making
window and lower quality glass and a `white house' for manufacturing flint
or lead crystal glass. In addition the inventory also records the goods
within the glasshouses including tools, moulds, crucible clay and raw
ingredients such as red lead, manganese and cobalt used for colouring
glass. The Silkstone glasshouses produced a range of products ranging from
everyday items such as windows and bottles as well as finer wares
including coloured glass with white trailed decoration. By 1707 the `green
house' had fallen out of use and was being used as a kitchen. Glass was
still being produced in 1718 but by 1748 it had ceased production
completely. In common with other small scale glass producers in the area
the Silkstone works suffered from a lack of investment and an inability to
compete with new technologies and large scale specialist production in
operation elsewhere.

By 1754 the former glassworks site was in use as a pottery producing simple
country earthenware for local markets. An illustration of the pottery from the
early 19th century shows the clay preparation area, the workshop and a tall
round kiln with at least three flues.

The excavations in 2002 comprised two trenches; one within the western
part of the former pottery building and one approximately 1m to the south
of the building. Excavation within the building revealed significant
amounts of debris from the pottery including pot fragments, wasters and
possible kiln fragments. Below this layer of pottery debris there were
remains of a glass working floor 0.5m below current ground level which was
composed of ash and coal dust and fragments of glass and solidified drips
of glass waste. This floor layer extended south below the south wall of
the pottery building, however it was laid against the footings of the
western wall of the building showing that this part of the wall was
contemporary with the glass working floor and formed part of the earlier
glassworks structure. This relationship demonstrates that the demolished
building was part of the 18th century pottery and was built on top of the
earlier glassworks, one wall of which forms the footings for the west wall
of the later building. Under the glass working floor were found deposits
of building rubble which included burnt sandstone blocks and waste glass
interpreted as the debris from a demolished glass furnace and some
sandstone fragments from the demolition of an as yet unknown building.
Below this building debris at a depth of 1m below the current ground level
a further floor level associated with glass working was discovered, this
floor extended beneath the glassworks wall.

The second trench south of the demolished building was excavated to depth
of 0.5m and revealed similar deposits to the first trench, in addition it
exposed the upper part of a stone wall at the southern side of the trench.

The excavations showed at least two phases of glass working on the site,
separated by a period of demolition and rebuilding of a furnace and other
structures. Although the excavations did not expose the full extent of the
glasshouses evidence from elsewhere indicates that glassworks of this period
included single glasshouses which took the form of square or rectangular
buildings measuring up to 15m by 10m along with associated features such as
workshops, stores, fuel and waste dumps.

Immediately to the north and west of the former pottery building, but
lying within the western and northern parts of the scheduling, lies the
site of a building which was demolished in the 1930s. This is believed to
have had 17th century origins and to have been associated with the
glassworks as workshops, stores or for domestic use.

A number of features are excluded from the scheduling. These include the
above ground remains of the former pottery building, the telegraph pole
and the greenhouse and ramp in the south east corner. The ground beneath
these features is however included.

MAP EXTRACT
The site of the monument is shown on the attached map extract.

Source: Historic England

Reasons for Scheduling

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.

Potteries were industrial sites where ceramic wares were formed and
fired. Some potteries were small scale enterprises worked by a single potter,
while others were much larger concerns. Kilns for firing the clay
vessels are usually the most prominent and easily recognised surviving
components. These kilns had a firing chamber, a sunken circular or oval pit up
to around 3m in diameter, into which the unfired clay wares were placed.
Leading from the firing chamber were one or more flues with stokepits
containing the fires for firing the pottery and drawing air through the kiln.
Situated close to the kilns were pottery waster heaps, workshops, drying
sheds, storage buildings, yards and hardstanding, clay pits and drains.
Although each pottery produced plain, decorated and/or glazed wares for local
or regional markets, the most commonly manufactured items such as cooking
pots, jugs and bowls, were similar in form throughout the country.

Excavations at Silkstone glassworks have demonstrated that significant
archaeological remains survive. In addition there is good quality
documentation providing an insight into both the social and economic
aspects of early Yorkshire coal-fired glass production. Together with
Bolsterstone 5km to the south it was the most successful of the early
glassworks in the region and marked the beginning of what was to become
one of South Yorkshire's major heavy industries. As one of few surviving
early coal-fired glassworks Silkstone offers great scope for the study of
this technology, both of early coal-fired furnaces in the late 17th
century and in the development from wood-fired forest glasshouses to the
later industrial scale coal-fired operations. Evidence of the later
pottery operations also survive and taken together the monument preserves
remains of the development of an industrial hamlet through the early
stages of the Industrial Revolution.

Source: Historic England

Sources

Books and journals
Ashurst, D, The History of South Yorkshire Glass, (1992)
Ashurst, D, 'Old West Riding' in The Silkstone Glasshouses, , Vol. VOL 12, (1992), 15-19

Source: Historic England