How Effective an Archaeological assessment can be made of
industrial remains at Silkstone.
By Rebecca Wake – A level Student May 2008
Plan of Procedure.
I decided to conduct my personal study on a local area to me that was always a point of interest, not
only to me but to the surrounding villagers, and as this study reveals, many within the archaeological
sector. Silkstone glassworks and pottery house were of interest to me for one main reason, the
closeness of the project linked the contemporary surroundings to its historic past. I began my
investigation by reading the excavation report that was produced after the excavation. (see appendix.)
As I read the report I separated it into three different areas, I highlighted excavation techniques and
finds, methods, and analysis. This made the report easier to understand and to collect the information
that was needed. Once I began my study I decided it would be beneficial to visit the site. I contacted
the owner and was shown around. I had the site explained to me from their perspective, which again
made it easier to fully comprehend and eventually really enjoy. I also researched how glass was
produced; I was finding it hard to understand some of the terminology used in the report so I found the
definitions on a glass-working site which really helped the study. There were many areas of success
within my project. The current owners were very helpful and answered any questions that I had, as
were English heritage when I contacted them about the artefacts. I was able to visit the site which
increased my understanding of the site and the history behind it instantly. There were however some
problems that I encountered; most importantly, as the site was fairly recently excavated and currently
being scientifically interpreted. The owners had been able to keep a few small pieces of pottery from
the preliminary excavation as they were of less importance, (for pictures see appendix) They were
however of limited use to my study and only four small pieces of glass were included in that collection.
I contacted English heritage, who conducted the excavation, about where the artefacts were being held
and whether they were available to view. This is where I encountered the main limitation with my
study; the artefacts of main interest were being held in Portsmouth, and were not being moved to
Sheffield until later in the spring, too late for me to finish my study. This severely restricted my study
and the opportunity to visit them in Portsmouth, which was offered, was unobtainable. There was no
way around this problem so I addressed it by simply focussing on the line drawings from the report and
photographing the small amount of artefacts that remained at the site. This still enabled me to relate the
drawings to the descriptions in the report and to visualise the artefacts within the context they were
found. Although this was a problem however, it didn’t affect the success of my study. I organised my
written work into; an introduction, explaining the site, the phases that were recorded, detailing the
artefacts found there and a conclusion, summarising the site and its contents. The phase sections
contain what that phase contained and line drawings of the artefacts found. This was to maintain flow
and to keep everything about one phase together, allowing to be easier to understand. Throughout the
study there are appropriate pictures showing the site as it is now and as it was then. All the artefacts
pictures are in the appendix.
Contents Page
1) Introduction
2) Finds
3) Glass
4) Conclusion
5) Appendix
Introduction;
In this personal study, I am going to analyse the excavation and the report that followed it of Silkstone
glassworks. I have visited the site which has now been developed upon and read the excavation report.
I felt I needed to extend my minimal knowledge of glass and so researched into the manufacture of
glass, not just at Silkstone but for the general glass making industry. This thoroughly helped me to
understand the site more as well as any technicalities that arose throughout the report. I did however
encounter some difficulties with the study. Due to the nature of the site and the chemical analysis that
needed to take place the artefacts that were retrieved from the site were sent to a laboratory for
examination in Portsmouth. This distance subsequently made it very difficult to view the artefacts. I
therefore decided that the line drawings used in the report would be used as substitutes for the artefacts.
I was however able to view and photograph some artefacts that were retained by the owners of the site
for personal interest. These contained a large amount of pottery fragments and only a few pieces of
glass although glass-working waste was in abundance and therefore useful towards my study.
Background
The excavation of a 17th Century Glass and Pot house was conducted in 2002 over a four week period,
however it occurred in two episodes. The principal aim of the excavation was to establish the date of
the building and its possible association with the historical glass industry
Figure 1; What the Pot house and glasshouse looks like today.
Two miles west of Barnsley, the village of Silkstone can be found. A well known business complex is
situated across from the river as you enter the village via a wooded road. The site contains a prestigious
hair salon alongside the main reason for development, the Garden Centre. It is known as the “Pot
House Hamlet” and belongs to a local business named Tom Horsfield.
The area seems to have always been a site for activity and work as there are many establishments that
have previously been recorded to exist; such as a 17 th century Corn mill, a blacksmith’s shop and
numerous barns. They all appear on early maps, but were however demolished in the 1930s. The
inspiration for this project is the presence of two 17th century glass furnaces, which were used as the
first commercially successful glassworks in South Yorkshire. No map references to either of them have
been found, they were however written about on documented sources.
Figure 2; Shows a photograph of the pothouse in 1906.
Historical Background
A Glasshouse was established in the mid 17th Century, this was followed by pottery manufacture in the
18th Century.
The glasshouse wasn’t the first in South Yorkshire, there had been a small attempt at window-glass
production in Wentworth by the Earl of Stafford, however this ended in 1641 after 9 years, due to The
Earl of Stafford’s beheading.
Bolsterstone, along with Silkstone began the establishment of the glass making industry. The Pilmey
family resided at Silkstone with John Fox at Bolsterstone. The furnaces used in the industry ran off
coal, this meant that Yorkshire, with its vast coalfields and clay for crucibles, was a prime location to
set up the glassworks.
The Pilmey family emigrated from France in the late 16 th Century. They’re first recorded at Silkstone
in 1658 when John Pilmey married Abigail Scott, 3 years after her first husband, William Scott died.
The glassworks continued under the management of Abigail after John died in 1675. Abigail died in
1698 and ownership of the glassworks passed to John Scott, her son from her first marriage. Through
Abigail’s will we can be sure that there are two glasshouses; a “green house” and a “white house”, also
referred to as the “green ware chamber” and the “flint chamber”. Also mentioned in the will were some
glassworking materials that included Rape ashes and Red lead, Breeley sand and Fretting clay.
Evidence from John Scott’s will in 1707 shows only one glasshouse and described a building that
referred mainly to kitchen equipment this suggested that the business was in decline. Abigails grave
can be found with her first husband in Silkstone church.
The desktop study allowed me to understand the site in terms of history, however there were, as there
always are, limitations with it. The site isn’t a very large one and was excavated at speed which made it
rather difficult to find anything other than the original report to base my knowledge on. It isn’t a very
well known site either making different insights hard to find. Oral accounts from the owners of the site
were also very limited. They only seemed to have historical knowledge of the site and any questions
about artefacts referred me to the English heritage report, of which I already had.
Figure 3; Shows Silkstone
within Britain, Silkstone in
connection with other pottery
and glass-working sites, and
finally the glass house within
Silkstone and the positioning
of the pot ovens.
The Purpose of the Excavation
The cause for this excavation was mainly due to a development process of the “Pot house”. There had
already been a previous development of the site in the 1960s that led to the complete demolition of the
kilns used in the pottery phase of this establishment. The name of the site derives from the small
industry of pottery production that flourished at the hamlet after the glass phase. The archaeologist’s
aims were to establish the date of the building and how it may be associated with the historical glass
industry and to characterize deposits under the building, date them, and recover any evidence of glass
working. These aims could be seen as quite closed and non-expandable which reflects that it was a
salvage excavation and not a research one. The aims were achieved however and although they didn’t
expand then, the possibility of expansion is there.
Methods;
The methods used were simply traditional excavation techniques. Two trenches were dug, the first one
occupied the wet side of the cottage and the second was south of the cottages, this was to determine if
deposits went as far as outside of the building. There was limited space for physically larger
equipment, this therefore dictated hand excavation, this occurred over a period of four weeks in 2002.
Through field walking over the site there were other artefacts found in different areas. However due to
the limited time period allowed for the excavation these finds were documented but never explored. A
revisit to the site would allow further extensive excavations of this area and the possibility of
understanding more about the glass-working techniques and the artefacts that were made and found
there at Silkstone. Soil samples were removed in their stratigraphic sequence, over 400 were collected
from Silkstone.
Figure 4; Below is the plan of the building, drawn to show the positioning of the trenches which were
excavated. As mentioned above you can see trench two, south of the cottage.
Figure 5; This picture shows the
building that was present at the
time of the excavation, originally
the plan was to renovate and
refurbish
this,
however
the
excavation took place the building
became extremely dangerous and
was eventually destroyed. Some of
the lower walling
was saved
however and was used as the base
for the new development of the
Finds;
site.
There were many finds at the excavation so I’m going to show them chronologically, through each
stratigraphic sequence, called phases. The larger phase numbers indicate the newer contexts of the
sequence.
Phase 6;
In this layer, the most recent layer, several layers provided a chronology for the inserted walls
associated with the blocking of the archway and the sub-division of the building. The roll-stamped
stem was retrieved from phase 6. The stamp was incorrectly cut, it is known to be retrograde, the
lettering that was cut reads backwards.
Phase 5;
Thin layers of a clay floor remained [0002], below this was a grey silt layer [0007] and pottery
fragments were found in a red ashy matrix, [0009]. 98 pieces of pipe were found; 15 bowl and 83 stem
fragments all of which were recovered from 9 different contexts. Phase 5 had the most artefacts, 64
fragments in all. There was a limited range of pipes, dating from c.1700 – 30, this could indicate that
the build up of finds occurred over a limited period of time also. Here are the stem stamps; both found
in phase 5 context, one is marked with the letters IG and the other with an H.
The two stem fragments, found in phase 5, had ground down ends making them smooth. This may
mean that they were reused, used for doodling, someone even suggested that it may have been used to
curl hair. Considering the context of the site however and the industrial focus it may seem more likely
that reuse was the reason.
Phase 4;
Here a hard packed layer of black ash and coal dust was found the grey ash [0014] and the black ash
and coal dust [0017] both contained glass fragments and glass working waste.
This layer extended underneath the existing building and in the context [0014] pipes were found which
were dated to c. 1690-1720. The earliest Bowl form is that in figure 6:1 dating back to the late 17 th
century or the early 18th century. And was retrieved from [0017] in phase 4. The majority of the other
bowl forms are early 18th century and the most intact can be seen in figure 6:2 – 5. Although many of
these finds were fragmented they are still a good indication of the type of styles that were being used in
Yorkshire at this period.
Bowl forms 3 and 4
5 maker’s marks are recorded at Silkstone; two heel stamps, two stem stamps and one roll stamped
mark. The following are line drawings of the stamps;
This heel stamp came from Phase 4 and was dated
to the late 17th century. You can see the mark, IC,
the only maker known around this time was John
Chapman in Hull.
This heel stamp shows the marks MH, there is no known maker during this time, however it is of a
local type and design.
Phase 3;
Two thick deposits of Sandstone rubble [0018] and [0028] were covered by a thinner layer of loose ash
[0027]. This layer is believed to be the results of the demolition of the furnace and the attendant
building. [0018] contained slag and burnt/vitrified sandstone along with many crucible fragments. This
was found above [0028] which contained un-burnt sandstone fragments in clean sand, again indicating
the presence of the furnace.
Wall foundations were also present [0025] to the right of [0018] and [0028].
Phase 2;
This layer was below the demolition rubble. A thin layer of grey clay was below this [0019]. Below
[0019] was [0020], a compact layer of black coal dust. There was wall to the west [0025], and also
found in [0020] were crucible fragments.
Crucibles are used for preparing glaze in.
Phase 1;
There are two features cut into the natural silt here;
1 –A post hole [0039], this was filled with glass vessel fragments and,
2 – A small circular pit filled with burnt sandstone fragments [0036]
Figure 6; This is the Stratigraphic sequence for
the Silkstone site;
The numbers that
can be seen down
the side of the
trench are referring
to the phases
mentioned above.
From the phases and the sequence that I’ve looked at I think the site shows evidence of multiple use
and that it isn’t a single phase site. Phase one shows post holes and the evidence of a building. Phase
two shows demolition of such building and phase three shows traces of a furnace, something built after
the demolition of that first structure. The remaining phases contained rubble and artefacts, as
mentioned above, that were related to the glass working house. This could suggest that this may have
been the final phase of the site.
Glass;
Within such a small area, a large amount of glass was found, many were main body fragments that
were unidentifiable but some of the vessels could be identified. There are three broad categories of the
vessel glass used at Silkstone, of which will be used to simplify the understanding of the finds
recovered. These categories are; - Colourless and Monochrome glass
- Splash Decorated or ‘Nailsea’ glass
- Natural green, brown or black glass.
There were very few fragments of any kind of window glass and the few that were, were all found in
phase 5.
Colourless and Monochrome Glass;
Here were found three types of glass forms, wine glasses, tumblers and jellies or bowls. Some of the
designs are similar to those that were made at Bolsterstone and Gawber, the first is highlighted on the
map on page 1. The glass forms above are shown in the below line drawings;
A fragment of cylindrical rod with an internal coloured twist consisting of opaque white, blue, yellow
and purple threads was found, it was too narrow to have been a stem from a wine or cordial glass, it
was possibly just an off-cut. There was a single fragment of bright blue glass that was also found, this
was interpreted as the lower portion of a fine handle from a jug with a pronounced lower thumb rest.
Splash-decorated Glass;
There were 8 small fragments of this glass found, they were from 5 different monochrome vessels and
were recovered from phases 3 – 5. The colour of the base glass varies from blue, green, amber and
colourless with the splash decoration being white. Two of the artefacts could be identified, however
only as “beakers”.
Naturally coloured green, brown and black glass;
The majority of the vessel glass fragments that were found were naturally coloured, brown or black
glass. What was found can be divided into fine-wares, phials and bottles.
Fine-wares; Found were three beakers, a dish and a Wrythen which is a decorated flask. The line
drawings of these are demonstrated below.
The closest any links from these could be made to any other site is not at the previously mentioned
Bolsterstone and Gawber but at Haughton Green.
Phials; The most common vessel found at Silkstone was the phial, it is a globular phial dating to the
late 17th century. The design of the cylindrical phial first occurred here during the late 17 th century, this
style became the predominant phial form that was used during the 18 th century. A number of the
globular phials found have unworn bases and in some cases the rims are slightly rough an unfinished.
Bottles; The remaining fragments are from at least 7 wine bottles and this is probable an
underestimate.
Glass-working;
The Technological Background; Types of post medieval glass;
Although the excavation didn’t recover any in situ evidence of a glass furnace it did provide a lot of
glass-working waste. Scientific techniques were used to characterize the glass manufacture. There were
400 samples collected from Silkstone, compared to the slightly smaller numbers found at Haughton
green (5), Gawber (7) and Bolsterstone (15). These helped archaeologists examine the chronological
changes in glass production technology.
Types of glass-working waste;
Glass-working waste consists of moils, threads, runs, droplets, frothy glass waste and chunks of glass,
other evidence for waste can also be found with crucibles. The threads were found by sieving soil
samples and most of the glass-working waste was recovered from phase 2 and 4 contexts.
Moils; Moils are Small, near-cylindrical fragments of glass that have been attached to the blowing iron.
Glass Threads; These are formed when a glass worker gathered glass from the crucible, applied trail
decoration, or tested the viscosity of the glass.
Figure 11; A Glass
working
They
tend tothread
fall to the ground in the immediate vicinity of the “glory hole” of the furnace and/or the
glass-workers chair. There was a low concentration of threads (0.01% at Silkstone compared to 2.5% at
Bolsterstone), this suggests that the excavation may have taken place some distance from the furnace.
Runs and Droplets; These are small pieces of glass with flowed surfaces, most of them bear the
impression of the ground on which it fell.
Frothy Glass Waste; This waster resembled the other glass working waste from the site but it had a
vesicular texture.
Chemical analysis of the glass-working waste;
Waste was recovered from phases 1, 2 and 4. The chemical analysis showed that several different types
of glass were produced at Silkstone. The Pilmeys produced two different types of glass; “green glass”
and “white glass”. Green glass was the most common. This could show a low status glass was being
produced for everyday use. Green glass from phase 1 and 2 shared the same chemical composition, but
the green glass from phase 4 contained less potash. This could have been due to the change in raw
materials, especially plant ashes. The white glasses were initially mixed alkali glasses but this process
was abandoned in 1680 for lead crystal/flint glass. This change to a higher quality glass again could
indicate that a higher status glass was being produced in the form of fine-wares.
The plant ashes used in the white glass was possibly more carefully selected because they contained
lower levels of iron oxide than what was found in the green glasses, this resulted in a paler green
colour. The green glass was used to make some of the fine-wares, such as the beaker and the dish or
jar, as well as phials and wine bottles.
The lead glass was then used to manufacture drinking glasses. Shown in figure 12 below;
Determination of Furnace temperature;
Crucibles are composed of three phases; quartz grains, vitrified clay and voids. 14 samples of crucible
were fired, in effect re-fired, at temperatures between 1,200 and 1,600ºc. The samples that were fired at
1,300ºc showed no change in the proportions of quartz, etc. above this temperature the proportion of
quartz decreased and the amount of vitrified clay increased. This meant that the crucibles hadn’t
previously been exposed to temperatures above this.
From sources other than the excavation report I was able to find the possible design of the furnace,
(See appendix, figure 13). The original design allowed the glass to be placed on top of the heat source,
usually coal. This caused the glass to become cloudy from the smoke that surrounded it whilst in the
kiln. This may have been used for the lower status glass. The Pilmeys are believed to have remedied
this by creating a small chamber above the heat source with an exit area to the side in which the
materials could be added and then retrieved. This chamber prevented cloudiness of the glass, allowing
this to be used as more decorative and higher status objects. The presence of a furnace would have
completed the excavation and the following report as it would have allowed further expansion of the
site and the size of the production going on there. Without a kiln or furnace of some sort,
archaeologists aren’t able to establish the true size of the site. If the glass Pilmeys changed very little
about the composition of the glass, then the glass found could have been made over a long period of
time, only in small quantities. The size of the furnace could help to indicate the true size of the
industry, allowing archaeologists to fully understand the extent of the glass-working. Without the
furnace there is very little interpretation that can be made about the size of the site, as the amount of
artefacts found could misrepresent the production size.
Conclusion;
The Silkstone site was excavated as methodically and successfully as possible with the time and space
limits that were encountered. This limitation did however create some problems for the archaeologists.
There was no furnace found at the site and throughout the report it is mentioned that the trenches may
have been too far out to find it. Within the Stratigraphic sequence two layers of sandstone, one burnt,
one not, was the only clue to a furnaces presence. If it was believed that the furnace was elsewhere on
the site why not focus the search there? Again time and space was an issue but surely the finding of a
furnace is almost a definite indication to an industry, whereas glass fragments and waste could
effectively indicate trade, or a one-off production. The owners of the site wished to erect a display for
the glassworks which would allow the public to learn about everything that went on there, like me
however they haven’t been able to do this, as the artefacts have been kept in Portsmouth. The report
was written in 2006 so I am assuming that all of the scientific analysis had been completed, why
therefore are the public and the owners of the site being withdrawn from this for another two years?
There were very few failures about the excavation, the furnace, or the lack of one, being it. The limited
amount of time was due to development of the site, why could this not have been disrupted for the
preservation and conservation of an archaeological site? I think it was a major flaw to not attempt to
find the furnace. This is a much needed area that must be explored in any future excavations to ensure
an objective overview of the glass-working industry in the 17th and 18th centuries.
Bibliography

Glass-working at Silkstone – Excavation report by David Dungworth, Tom
Cromwell, Dennis Ashurst, Chris Cumberpatch, David Higgins and Hugh
Willmott.

Technology Report - By David Dungworth.
Websites

www.englishheritage.co.uk

www.glassworking.co.uk
Acknowledgements
I would like to make a special mention to Dr. Hugh Willmott for his time
and the contribution of his knowledge to the study. I’d also like to thank
Emma and Tom Horsfield for allowing my study to take place and for the
information they gave me.