Summary
The remains of a chemical explosives factory known as Cliffe Explosives Works comprising both upstanding structures and buried remains, established in about 1890, gradually expanding in the late C19 and early C20, with massive expansion during the First World War, and which was active until about 1920-1921.
Reasons for Designation
Cliffe Explosives Works, a chemical explosives factory, established in about 1890 which gradually expanded in the late C19 and early C20 before experiencing massive expansion during the First World War, is scheduled for the following principal reasons:
* Rarity of site type: the eastern extension to Cliffe is the best surviving example of a purpose-built First World War cordite factory nationally (a rare factory type) retaining the largest surviving group of First World War factory buildings in the country;
* Survival/condition: the factory survives in a remarkably complete form and possess the highest number of standing buildings and structures on any explosives factory nationally; the completeness of its plan and legibility of its process-flow is significant in allowing an understanding of the complexity of the manufacturing process and the dangerous nature of the work undertaken here;
* Period: Cliffe Explosives Works is one of only a handful of explosive factories nationally that exhibit much of their pre-First World War plan, as well as significant First World War development;
* Rarity of fabric: despite being relatively cheap and fireproof, the use of reinforced concrete for buildings associated with explosives manufacture as here was most unusual at this date;
* Diversity: the variety and diversity of features of the former factory is clearly evident in its morphology and plan;
* Documentation: the factory is very well documented given an English Heritage archaeological survey and research report in 2010-11.
History
In about 1890 the gunpowder manufacturing firm Hay, Merricks & Co Ltd (from Roslin, Midlothian in Scotland) acquired a site at Lower Hope Point on the Hoo Peninsula in Kent for a new gunpowder factory. Their draft licence of the same year indicates that the original intention was that the factory would blend and store gunpowder only, and not manufacture it on site. The accompanying plan showed an area in the north-west corner of the present extent of the former factory and included the proposed layout of structures and a specification for their construction.
In December 1892 the company was granted a licence by HM Inspectors of Explosives for ‘blending, dusting, drying and packing gunpowder’ and the Cliffe factory was added to the national register of licenced explosives factories as Factory No 154 (Pullen et al, 2013, 21). Initially only two buildings were constructed, linked to a jetty on the River Thames by a tramway. The site essentially seems to have functioned as a large magazine in its early years until it passed to Curtis’s & Harvey Ltd in 1898 (Hay, Merricks & Co and eight other gunpowder firms were incorporated in Curtis’s & Harvey as a newly constituted public company). Curtis’s & Harvey saw the potential of the Cliffe Marshes site as a factory for explosives manufacture. It was remote (essential for such a dangerous enterprise), flat and large (offering potential for expansion as well as sufficient space between operations for safety), and yet had good communications because of the adjoining river. Curtis’s & Harvey bought additional land from the Cobham Hall Estate and continued to buy more land over the next two decades to expand their enterprise.
In the very late C19 and early C20 there was a move away from gunpowder to new explosives, specifically cordite; a new smokeless propellant. The demand for this product rapidly increased given a precarious international situation and the great naval race between Britain and Germany in the early C20. On 3 June 1901 an amended licence recorded that gunpowder, guncotton and nitroglycerine-based explosives, including cordite, blasting gelatine and gelatine dynamite, were being manufactured at Cliffe. However, given such rapid technological developments, by 1902 its authorisation for gunpowder - which was by then considered rather old-fashioned - was withdrawn. By 1904 the factory was also licensed to manufacture cordite MD (a particular form of cordite that required less nitroglycerine in its manufacture) and Cheddite (a chlorate-based explosive). Dynamite production began a year later and between 1904 and 1908 the number of structures on the site increased dramatically such that by 1908 the HM Chief Inspector of Explosives described the factory as the largest in the kingdom. Records from the early C20 indicate that some employees of Curtis’s & Harvey were already highly skilled in working with explosives as they transferred to Cliffe from other explosives factories such as the Royal Gunpowder Factory, Waltham Abbey and Pitsea Hall Farm, both in Essex.
The First World War created a demand for explosives on an unprecedented scale but despite a near fourfold increase in production by March 1915 this was still insufficient. In May 1915 following the 'Shell Shortage Crisis' the Munitions of War Act was passed establishing a Ministry of Munitions and a national armaments drive, increasing state control of production. The Act allowed the government to categorise some essential factories as controlled establishments, that were essential to the war effort, and the factory at Cliffe was declared such on 6 March 1916. During the war land acquisition here continued apace fuelled by demand, to a peak holding in 1916. The first major expansion of the factory in the First World War, in the east and south-east of the site, was known as HM Cordite Factory, essentially signifying the ‘transfer’ of manufacture from the private company to one that was government run (although Curtis's & Harvey continued its association with the site by acting as managing agent on the government's behalf).
The end of the war saw a dramatic reduction in production at explosives factories nationally and some ceased to exist. Manufacturing at Cliffe seems to have pretty much come to an end by 1920-1921 although some storage use continued. The eastern section of the site (HM Cordite Factory) was sold to the War Department in November 1921 and by May 1922 records indicate that the whole factory was in the course of demolition. This included the removal of all material which could be re-used or had scrap value, as well as probable ‘thermal remediation’; setting fire to structures to remove chemical and explosive residue. The War Department land was sold off privately in 1923. Curtis’s & Harvey continued to own the western part of the site until circa 1931 when it transferred to the Port of London Authority.
During the Second World War the former factory site saw occasional military training use, was a site for ammunition disposal and was also used in small part for aerial target practice (bomb craters have been identified on site). The landward ends of the four jetties were demolished as an anti-invasion precaution.
Sometime after March 1981 the sea wall and its landward drainage dyke to the north and west of the factory were rebuilt and re-cut respectively, moving inland by about 90 metres and therefore damaging or destroying some of the factory remains on the very edge of the Thames. In 2010-11 the former factory was the subject of research and detailed survey by English Heritage. More detail on the site’s establishment, development, operation and history can be found in the accompanying English Heritage research report (Pullen et al, op cit) as can an overview of the factory’s products and manufacturing processes; also a comprehensive survey plan of the archaeological remains of the full site. The site is now (2019) grazed by tenant farmers.
CORDITE MANUFACTURE
The main explosive manufactured at Cliffe Explosives Works was cordite. Cordite was made by blending dry guncotton and nitroglycerine, plus a very small amount of mineral jelly (vaseline), in a ratio of 37:58:5. Nitroglycerine would be introduced to a batch of dry guncotton by pouring it into guncotton boxes. The resulting mixture was known as cordite paste. This was then kneaded in a mixing house. The cordite paste then went to an incorporating house where the mineral jelly and acetone were added (to respectively chemically stabilise and make the paste more maleable). The mixture, now known as cordite dough, then went to a press house where it was pressed into long cords (hence the name 'cordite'). The cords were then processed in an acetone recovery store where the acetone was removed. The finished cordite then went to a blending house, where cords of the same diameter were placed in bundles, before going to a drying stove to drive off any remaining moisture, before being stored in a magazine ready for shipping to a filling factory where it would be assembled in propellant charges and rounds as required. The former explosives factory at Cliffe clearly illustrates all the stages of this process with the form, plan and relative position of the physical remains enabling an understanding of which manufacturing processes took place in which buildings and areas. The site was physically organised according to process and risk, and was essentially divided into different factory departments through which the manufacturing process flowed.
Details
The monument includes the remains of the former Cliffe Explosives Works, a chemical explosives factory comprising both upstanding structures and buried remains, established in about 1890, gradually expanding in the late C19 and early C20, with massive expansion during the First World War, and which was active until about 1920-1921.
The site is extensive, covering approximately 114 hectares of estuarine marsh (the Cliffe Marshes) in the north-west corner of the Hoo Peninsula in Kent. It is bounded on its north and west sides by the River Thames where it broadens into the Thames Estuary, where there is a high sea wall behind which (to landward) is a deep drainage ditch. The detailed description of a site of this scale is beyond the scope of this document and is covered in detail in Pullen et al (op cit) from which the following summary draws heavily. The English Heritage survey divided the site into ten areas (labelled A to K) and this convention will be followed below. This description does not attempt to describe every feature present – the number is far too great – but rather will characterise briefly the remains in each area. It is worth noting that many of the structures on site originally had superstructures of either timber and or corrugated iron, often lined either with canvas or match-boarding, These have all been removed. However there are extant concrete and brick structures and extensive earthwork remains and footings.
DESCRIPTION
OVERVIEW AND FACTORY-WIDE FEATURES
As a factory dealing with dangerous materials, safety was of paramount concern. Very many of the buildings at Cliffe are protected by earthen traverses such that in the event of an explosion the traverse would prevent the impact of the explosion from affecting neighbouring structures. When new buildings were added, their relationship to the tramway network (see below) and the orientation of their entrances and form of traverses was dictated by the nature of their surroundings and their potential to threaten or be threatened by their neighbours. In addition, the large amount of land at Cliffe allowed the ‘danger’ buildings to be spaced out, and when operational the factory site also had considerable tree cover with trees probably planted as additional protective blast barriers. The site also needed to operate efficiently so layout of the whole, and the interconnection by transport between individual processes in the factory, was also of great importance and therefore the layout of the factory’s extensive tramway network is a key characteristic of this site. The tramlines were narrow gauge and ran on low embanked earthworks above the marshland. Small hand-pushed carts (known as ‘bogie carts’) transported materials and explosives between the different processing areas. The earthwork survival is very good but there are also some sections were the concrete tram bed and rails survive. Other communication routes within the site are very limited. There is the main arterial road in from the south through Areas F and B to the river, with its branches into Areas A and G, and a very small number of pathways showing as shallow earthworks. There are also a number of concrete plinths and concrete or timber post alignments. These were usually to carry pipelines or cables above ground level.
Water management was also important: the factory was laid out in an area of marshland that was already criss-crossed with drainage dykes. These remain a highly visible part of the site and would have been crossed where necessary by bridges (where tramways had to run across them; most evidence for bridges has now gone). Added to these were further drains, pipes and culverts laid out as part of the factory construction to both manage water for factory processes and to assist in flood alleviation.
Overall the factory plan in its earlier phases appears to have been laid out and to have expanded in an organic manner, respecting pre-existing landscape features, whereas the First World War HM Cordite Factory is rigidly planned and laid out regardless of the pre-existing drainage pattern.
AREA A in the north-west of the site (circa 1893 Hay Merricks & Co; also pre-1907 OS development). This area includes the earliest features associated with explosives, for blending, packing and storing gunpowder; also the pre-war nitroglycerine factory. Area A was constantly remodelled during the factory’s life, including infill development.
The earliest surviving elements of the factory – Structures 1 and 2 – are found here and were linked to Jetty 1 by tramways. Documentary evidence indicates that these were built in the early 1890s and were used for the blending, packing and storage of gunpowder that had been manufactured in Scotland. Both exhibit a form of earthwork protection that is not found anywhere else on site as they have clasped opposing earthwork traverses with two entrances to the central ‘danger’ building with a concrete rectangular building foundation. The foundations indicate that the form of the two buildings was different and they have also been adapted and reused later on, possibly as mixing houses for combining nitroglycerine with guncotton to create cordite paste. In the north-west of the site is a group of small simple structures in three north-south rows. Each has a level platform protected on one or more sides by an earthen mound. They are interpreted as having been small wooden huts (the superstructures do not survive) for packing cartridges for explosives such as dynamite or Cheddite.
The proximity of Area A to the river means that it is also characterised by a number of storage-related structures and as these are not usually protected by traverses the assumption is that these stored inert materials. The unusual form of Structure 24 is perhaps the most noteworthy as it has a reinforced concrete trapezoidal yard with a possible loading bay to the rear (north). Further bays used to exist but were removed when the sea wall was rebuilt. Immediately adjacent to it is a red-brick, single storey building (Structure 23) which had a double-pitched roof (although the roof has largely gone). This is interpreted as a pair of small offices with a storeroom, weigh room or workshop attached which managed goods in and out of the factory.
In the south-east part of Area A is a nitroglycerine factory. Most distinctive is Structure 31 as it stands to about twice the height of most other traverses nearby at about 3.2m. Also its sub-circular traverse is stepped in profile, a feature which is unique at this factory. In the centre would have been a lightweight two-storey nitroglycerine house, where acids were combined with glycerine to form nitro-glycerine (now gone). This was accessed by a robust brick-revetted passage through the traverse. This building is known to have been the site of a serious accident in 1911 and that some necessary remodelling followed this. Flanking this nitroglycerine hill are the remains of two circular wash houses (where excess acids would be removed from the nitroglycerine), both having well-formed steep-sided mounds, in the centre of which are roofless circular and substantial brick revetments accessed by arched entry tunnels. It is thought that free-standing round timber washhouses would have stood in the middle. There are other nitroglycerine buildings in this group and one such, Structure 27, is noteworthy for being the largest of the single-storey rectangular-mounded structures on site: it has a unique form of traverse arrangement with a C-shaped traverse protecting three sides of the building and a straight traverse to protect the fourth. It is interpreted as a possible mixing house where nitroglycerine could have been mixed with a variety of other materials to make different types of blasting explosives.
AREA B in the west of the site (developed by the time of the 1907 OS map with 1907-14 alterations). A zone of acid-handling, guncotton preparation and utilities; also administrative and support buildings. The western portion of Area B is dominated by a complex of concrete building foundations, often including a dense pattern of plinths and tanks, laid out in a linear arrangement along both sides of the main east-west road. These buildings were in the main for handling acids and producing guncotton including some dedicated to generating energy for these processes. Structures here are largely in the form of concrete building slabs or foundations with little surviving above foundation level apart from a number of machine plinths (particularly in Structures 43 and 44 which may have been the powerhouses for this part of the factory). Identification of function is not certain but, for example, it may be that Structures 35 and 36 may have been where the cotton bales were broken up and cleaned by picking and willowing, and Structures 38 and 39, which have flooring and drains made of acid-resistant blue brick, and 63 are likely to have been involved with acid handling, either nitration (or ‘dipping’) of the cotton, washing and pressing the saturated cotton charges, or may have related to storage of acid. Structure 41, which distinctively contains the outline of three evenly-spaced large circular concrete pads, probably held three large tanks for washing or spinning as part of the guncotton manufacturing process. There are also the remains of a rifle range and target which were used for testing cartridges manufactured here.
The south-eastern area, either side of the tarmac road, contains a collection of concrete foundation slabs and the standing remains of three brick buildings. Here were offices, domestic buildings and support facilities such as changing rooms and canteens. Structure 46, which survives only at foundation level, may have been the main office building for the factory. A further group of administrative, domestic or supporting function buildings survive to the south of the road. These include Structure 65, a small single-storey brick building with a replacement corrugated roof and internally plastered walls, which is now used as a hay store. Next door is Structure 66, the remains of a brick cottage known as ‘The Poplars’. This is a largely collapsed building apart from several sections of standing internal walls including an off-centre brick chimney stack. This may have always been a domestic building for an on-site manager or foreman, or may have been adapted for domestic use after the factory closed (map evidence suggests it may still have been in use at least into the 1960s). Another building which stands to a reasonable height, although without its roof, is Structure 67, a building on a concrete foundation which is of brick pier and rendered panel construction. The function of this building is not known but there is evidence of an end chimney stack and fireplace indicating that it was used for a function other than simply storage.
AREA C in the south-west of the site (part of the 1907 to 1914 expansion). North of the Delph ditch are filling huts for packing explosives. These are small structures laid out in five parallel rows and while broadly homogenous have some distinctive characteristics. They all comprise concrete bases for small huts/sheds protected on at least one side by an earthern mound. There is one distinctive small, brick-built and cement-rendered, barrel-vaulted structure (Structure 95). It used to have a partner structure but this was demolished at some point between 1995 and 2010. Evidence that there was once a very heavy duty door to this structure and its form has led to the interpretation that it may have been an expense magazine for holding particularly sensitive small explosive components. South of the Delph ditch is a group of six dispersed ‘danger’ buildings, as evidenced by their large protective earthern traverses. The marginal position of these buildings implies that they were for alternative products to cordite, possibly Cheddites or gelatine-based explosives, and their size would suggest that they were used either for the mixing of materials or the storage of the finished product, or possibly a combination of the two.
AREA D in the centre north of the site (all largely developed by the time of the 1907 OS map, the western part was remodelled as part of the 1907 to 1914 expansion). This is a cordite processing area established before the First World War. The plan of the structures is in three distinct parts: in the north-western corner is a Y-shaped group of building foundations which were associated with early cordite production; the north-eastern part of Area D houses a series of small dispersed buildings with protective earthen traverses, whereas to the south-west are a number of densely spaced very large concrete buildings, largely without traverses, which were initially cordite drying stoves that were converted in 1914 to be used for acetone recovery. The Y-shaped group (Structures 106 to 114) consists of large concrete building slabs, none of which have any upstanding remains although witness marks in the slabs aid interpretation. Here were press houses (including the surviving plinths for hydraulic presses), a hydraulic accumulator base, and a possible incorporating house. The survival of tramlines linking all the structures is particularly good in this part of the site. It is not possible to confidently identify the functions of all the buildings from their physical remains, but Structures 115 to 120 were for some time about 1907 associated with the Coventry Ordnance Works Ltd and used for cartridge and shell filling (see The Engineer 1907a & 1907b), and the rest are believed to be cordite processing and storage buildings (magazines). Structure 127, for example, is of a distinctive form with its asphalt-covered square building platform divided into four equally-sized compartments. This plan-form is associated elsewhere on site with cordite drying, each room being a cordite drying stove (see Areas E and K). The acetone recovery group is characterised by a number of very similar and long east-west building foundations with double rows of cells along their length. Documentary evidence of an accident in one of these buildings (Structure 129), where an explosion killed labourer Jon Geer while carrying out alterations to turn a cordite stove into an acetone recovery stove, indicates the primary function of at least this one building. Other structures related to acetone recovery include Structure 132 which has a distinctive acid-resistant blue brick floor and drains, and a possible boiler house (to provide steam to heat the stoves).
AREA E in the centre of the site (part of the 1907-1914 expansion). Area E is an area of drying stoves for guncotton and cordite, each type being distinct in its physical form, interconnected by a complex network of tramway embankments. The south-west side of the area contains seven evenly spaced concrete building foundations, each tightly encircled by a protective earthen traverse with a gap for access from and onto the tramway system. These are mostly interpreted as guncotton drying stoves as they also have the accompanying small exterior hut bases (as in Area H below) which are likely fan sheds for driving hot air through the stoves. The superstructures for the stoves and fan sheds are missing but comparison of form with identified structures in the HM Cordite Factory and documentation for the same suggests that they would have had canvas-lined brick walls, timber and corrugated iron roofs and asphalt-surfaced floors. The fan sheds were probably built with timber and corrugated iron walls and roofs. The north-east side of Area E contains the remains of eight square structures arranged in three east-west rows. These are cordite drying stoves. The eight structures survive to varying degrees from foundations slabs to standing but roofless structures. All are of the same arrangement however, in being divided internally into four equal rooms (each room a drying stove), and exhibit a clear adoption of a new and safer construction method in changing from brick to reinforced concrete partway through the development of this area. The earlier stoves all had linear traverses to their north as in the event of explosion their brick-built superstructures could have resulted in flying debris. This is not the case with the southern pair, Structures 153 and 154, which are the best preserved and are also the later examples, as they are built of reinforced concrete, so a protective traverse was not considered necessary. The use of reinforced concrete in an explosives manufacturing context was unusual at this date.
AREA F in the centre south-west of the site (north-east of the road was developed by 1907, south-west of the road was part of the 1907 to 1914 expansion). Area F is bisected by the main site road which runs broadly north-west to south. North-east of the road is an explosives processing area, a linear trio of settling ponds, and buildings which may have been guard huts/accommodation and changing facilities near the main factory entrance (employees had to change into appropriate safety clothing before entering the site proper). The structures associated with explosives manufacture and processing in Area F are unusual in form. The principle features are the remains of what had been three very square traverses. Of these Structure 156, is unique on site in that its interior brick revetment has rounded corners. This may reflect an anti-explosion device developed at the Nobel explosives factory in Ardeer, North Ayrshire which was rapidly adopted at Waltham Abbey, and then possibly here at Cliffe in this building and in the circular nitroglycerine buildings in Areas A and I. The specific function of these structures is not known but their unusual form and position away from identified guncotton and cordite related processes implies that they relate to the manufacture of a different form of explosive, perhaps the mixing of ingredients to form Cheddite which, as it does not require nitroglycerine, could account for the particularly distinctive form of these buildings. South-west of the road is a largely undeveloped area but which still contains some factory features such as a small group of structures hugging the bank of the Delph Ditch and served by an embanked tramway approaching them from the north. These are of concrete and brick with evidence of earthern traverses, and given their form Pullen et al (op cit, 170-172) suggest that these may represent unfinished or part-destroyed (through explosion) nitroglycerine buildings.
AREA G in the south of the site (part of the 1914-20 expansion). This area is part of HM Cordite Factory and dealt with acid-handling and guncotton preparation, there are also some support and administration buildings (Areas G to K represent the rapid development of the site for producing guncotton and cordite for the First World War, most development beginning in 1914 and being complete within the first one or two years of the war). Area G contains a complex of interlinked buildings, which have largely been reduced to foundation (concrete slabs) or near foundation level, and which mark the entrance to the guncotton manufacturing plant belonging to HM Cordite Factory. The support and administration buildings include storage facilities and, in the extreme west of Area G close to the access road into the site, a set of changing rooms for staff to change into factory-issue safety uniforms before entering the processing area. In terms of acid-handling and guncotton production the structural remains in Area G reflect a number of essential processes including: the breaking up of the raw bales of cotton waste (the first stage in the guncotton manufacturing process); drying the raw cotton; a picking room (to take out any impurities); a willowing room (passing the raw cotton through a machine to break up the cotton ready for acid absorption); a nitrating house (or dipping room, where the cotton was immersed in mixed acid for several hours, the resulting material being guncotton); a boiling house (where the nitrated cotton would be boiled to remove any unwanted elements); a washing house (to beat and wash the guncotton pulp), and a settling house (where the guncotton was brought to a safe handling state with a water content of 25%). Guncotton intended for cordite manufacturing would have been kept wet but there is also a press house here which implies that some was not for cordite but perhaps rather for demolition charges and torpedo and mine filling. The remains vary in scale and form but are largely concrete foundations, but with a number of the structures including plinths with iron bolts and fittings indicating the positions of various pieces of machinery or plant. Perhaps the most distinctive surviving structures in this area are a group of five cuboid ones located immediately west of the engine house. Each has cement-rendered, thick brick walls with elements of an internal iron structure with some evidence of charring internally. They have flat or cambered concrete roofs. Their function is not entirely clear, possibly they were some kind of furnace for creating hot air for one of the processes in Area G, or perhaps were for waste incineration.
AREA H in the south-east of the site (part of the 1914-20 expansion). Also part of HM Cordite Factory and housing drying stoves for the finished guncotton. Area H is accessed by a single tramline leading from Area G. While the south-west part of H is largely undeveloped marshland, the north-east part houses a gridded arrangement of 17 large sub-rectangular earthen traverses, each paired with the remains of a small external structure on the north-east side. These are guncotton drying stoves and their fan sheds (housing fans to convey hot air into the drying stoves) respectively. The stoves have a central rectangular concrete building platform within their traverse. The fan sheds are small concrete bases with raised concrete plinths to support the fans.
AREA I in the centre south of the site (part of the 1914-20 expansion). This area is also part of HM Cordite Factory and interpreted as a second nitroglycerine processing area or ‘factory’. It contains a small number of large dispersed structures, laid out broadly in an arc, comprising three large earthen mounds with integral elements of structural brickwork, interspersed with small circular ponds (these may be settling ponds associated with the washing processes for nitroglycerine), brick plinths, and the usual network of tramways, paths and drains. The generous spacing of these structures is a physical manifestation of the volatile processes undertaken here and is no doubt a reflection of accidents that had taken place in the earlier nitroglycerine group in Area A. Structure 168 is a nitroglycerine hill and is one of the most imposing structures on the site given its scale (the protective mound is circa 4m high). This contained a nitroglycerine house, a multi-storey building where acids were combined with glycerine to form nitroglycerine. The centre of the open-topped mound, accessed via a brick revetted entrance tunnel through the earthwork, is revetted by a substantial hexagonal brick wall. This in turn would have protected a timber superstructure with a timber and felt roof (now gone). Once the nitroglycerine had been manufactured it would leave via a vaulted secondary tunnel to go to the washing and settling facilities which would remove any excess acids from the product. The other two circular mounds, with a circular footprint of 35-40m and standing circa 2m high, are interpreted as possible nitroglycerine wash houses but as they are subtly different, and both appear to have been blown up, this is not absolutely certain. They have doughnut-shaped traverses with large water-filled craters at the centre; both mounds have evidence of their original brick entrance and exit tunnels and of associated forecourts or catchment tanks.
AREA J in the east of the site (part of the 1914-20 expansion) and also part of HM Cordite Factory. After being mixed with nitroglycerine in Area I, cordite paste would then have moved north-east into Area J where all the final chemical and physical processes of cordite production were carried out. Area J is divided into two distinct areas. The south-east part is occupied by neat rows of large sub-rectangular earthwork traverses. While all of these structures in Area J are of similar appearance – with high earth banks around concrete building foundations with breaks in the banks to move material in and out from the tramways – there are subtle differences and they are functionally different with eight cordite paste mixing houses and four outlying magazines.
To the north-east is a long east-west alignment of large cordite processing buildings. In the east of the line is a building reduced to foundation level. This is an incorporating house where mineral jelly (vaseline) and acetone were added and thoroughly blended into the cordite paste. In the centre east of the line are two cordite press houses where the cordite paste from the incorporating house was passed through a hydraulic press and extruded into long cords of varying diameter according to need. These are a mirrored pair of elongated roofless reinforced concrete buildings each with nine individual bays on a concrete foundation. To their west are two paired elongated roofless buildings of brick and reinforced concrete construction which each comprise a central spine wall with thirty small compartments on either side, these are acetone recovery stoves. Tramlines run along the long sides of all the above buildings. At the extreme west of the line are two further buildings which have been reduced almost to foundation level which were also acetone recovery stoves.
AREA K in the north-east of the site (part of the 1914-20 expansion); the final area of the site, also part of HM Cordite Factory, where cordite was blended, dried and stored before being shipped off site (probably via the nearby jetty No 4). This is a very large and ordered area of buildings arranged in regimented lines and serviced by a grid of interconnected tramways: there are five parallel tramways aligned north-south and connected by junctions to a series of west-east tramways, which serve buildings located midway between each north-south tramway. Each junction has a corresponding small platform for the tumbler point controls (points levers used to control the routes taken by the bogie carts). The structures within the grid are of two distinct forms. There are 17 roofless reinforced concrete buildings; each partitioned into four internal spaces, and originally roofed with corrugated iron lined with asbestos cement sheet. These are cordite drying stoves, each quarter of the building being a stove (much like those in Area E) and 15 rectangular bases with no remaining superstructure in the north, middle and south of the grid. These are cordite blending houses and originally were match-lined corrugated iron structures on a timber and concrete floor. Along the eastern edge of Area K beyond the grid described above, is a broadly north-south line of five large sub-rectangular earthwork traverses surrounding rectangular concrete building foundations. These are magazines for the storage of finished explosives.
EXCLUSIONS
All modern structures associated with the grazing of the site, such as fencing and fence posts, gates and gate posts, feed and water troughs, are excluded from the scheduling although the ground beneath them is included. Bridges and associated structures across the sea wall drainage ditch are also excluded where they fall within the scheduled area, although the ground beneath them is included.
