Melin Mynach, Gorseinon

We were recently asked by Swansea Council and Mann Williams Civil Engineers to undertake a 3D photogrammetric survey of the Melin Mynach Scheduled Monument (SMGm501), a former mill site in Gorseinon, to inform on conservation management plans.

The site broadly consists of the remains of a medieval and Post-medieval gristmill, an early Post-medieval paper mill and later woollen mill. Cadw note that “…water power has been used at this location for a number of industrial purposes for a long period [of time]. The earliest mill is thought to be of monastic origin, possibly built after Neath Abbey took over the estate of Cwrt-y-carnau in 1150, and was probably a corn mill. The first documentary reference to a mill was in 1578. In 1772 it was converted for paper making, and was one of the first of its kind in Wales, in use for over a century. It was returned to use as a corn mill in the 1830’s, but in 1866 William Lewis converted the mill to woollen manufacture, enlarging it substantially in 1874. From 1888 the site was turned to chemical and tinplate manufacturing, and the mill itself became disused. The main surviving features are the leat, pond, paper mill, woollen mill, two wheel pits, dye-houses and the mill owner’s house” (Cadw).

The survey was undertaken with a high resolution camera equipped UAV (drone) and DSLR camera. The 3D photogrammetric model was produced using proprietary photogrammetry software and aligned using known ground control points (GCPs), which were tied into the Ordnance Survey National Grid and Datum using an RTK GNSS/Glonass (GPS) Receiver. The resulting Ground Sampling Distance (GSD) achieved 0.83cm/pixel. The 3D model produced a dense point cloud of over 171 million points and a high face count mesh (>34m), with a mean RMS error of 6mm. You can view a copy of the 3D photogrammetric model below that has been reduced in size/detail. The finished 3D model was so large (and detailed) we had to reduce it by around 70% to allow us to share online. 

We then produced series of high resolution measured orthographic plans and elevations to inform on the conservation efforts.

The Medieval and later Post-medieval Development of the Mill

The historical and archaeological background of Melin Mynach has previously been outlined in great detail by Martin Lawler (1990). So we’ve summarised some of his work below and augmented this where necessary with more recent archaeological developments to provide a little historical background to Melin Mynach.

Medieval and Post-medieval Gristmill

The medieval gristmill, also known as the Monk’s Mill, is understood to be of monastic origin. The site of the mill formed part of a grange attached to the east of Neath Abbey, which was established in around 1150. This monastic grange was known as Cwrt-y-Carnau. At the beginning of the 19^th century, a sizeable farmhouse (NPRN18500) was erected on the site of this former grange (Roberts 2014, 228). In terms of extent, the grange spanned an area between Loughor Estuary in the west to Afon Lliw in the east. It has been suggested by Williams (2001, 308) that the grange centred on NGR SS 593 988, which denotes a point on the eastern edge of Gorseinon. In total, the Cwrt-y-Carnau Grange formed part of a collection of seventeen estates over which Neath Abbey had control. The earliest reference to the gristmill at Cwrt-y-Carnau belongs to the sixteenth century and is recorded as occupying an area towards the western banks of Afon Lliw. As this reference was made several centuries after the construction and use of the Cwrt-y-Carnau mill, the process of definitively identifying the Melin Mynach site as its place of origin proves difficult. However, the Melin Mynach site is situated near the western banks of Afon Lliw and is the only site of this kind in the area. It may therefore be approximated that the gristmill at Melin Mynach did indeed form part of the Cwrt-y-Carnau Grange. In terms of its position, the mill would have been isolated from the chapel and grange centre, which were situated further west towards the Loughor Estuary. The chapel to which the mill originally belonged is known as St Michael’s, which today comprises a Scheduled Monument (SMGm363). Yet this was not an unusual situation for the time, as some other monastic granges in Wales were similarly arranged, such as those belonging to Strata Florida Abbey in Ceredigion and Whitland Abbey in Carmarthenshire.

The surviving features associated with the medieval gristmill include a small section of mill race, the mill pond and the earthen platform on which the mill itself was constructed. The mill race was one of the longest of its kind in Wales, measuring over 2.8km in length. The construction of this mill race, moreover, involved the highest engineering expertise that the twelfth and thirteenth centuries had to offer. The head race section diverted water from Afon Lliw towards the western edge of the Lliw Valley to a height of approximately 4m above the river. The tail race section then returned the water to Afon Lliw at a point near King’s Bridge. In terms of structure, little of the original medieval gristmill survives as it was reconstructed in the eighteenth century. Akin to other industrial sites belonging to monastic granges, the gristmill would likely have been managed by lay brethren. Following the Act of Supremacy 1534 and the resulting dissolution of the monasteries in England and Wales, the gristmill, along with the entirety of the Cwrt-y-Carnau Grange, was transferred to private ownership. As a result, the mill at this time formed part of a manorial demesne until as late as the nineteenth century. It was during this time that the mill was reconstructed and enlarged.

Post-medieval Paper Mill

The conversion of the former medieval mill into a combined grist and paper mill was commissioned during the early eighteenth century by Thomas Selman, the then proprietor of the mill. At this time, Melin Mynach represented one of the three earliest paper manufacturing sites in Wales. An earlier paper mill situated on the edge of Kidwelly in Carmarthenshire was previously owned by the Selman family. Yet for reasons unknown, the Selmans decided to transfer their paper manufacturing business from Kidwelly to Melin Mynach by 1729. Structurally, the new paper mill at Melin Mynach was composed of sandstone rubble walling.

The manufacture of paper at the mill involved the recycling of old textiles in the form of, for example, rags, cloth and cordage. These textiles were first cleaned and separated into individual fibres, in an operation similar to carding.

The separated fibres were then chopped and boiled before being transferred to the pulp mill which, it is presumed, would have been located near the water wheel.

Within the pulp mill, the fibres would have been pulverised via a series of timber stampers, which were operated via cams attached to the shaft of the water wheel. Moreover, the fibres were placed on a series of stone or timber mortars, meaning they were pulverised between the base of the stamper and the top of the mortar. These mortars were graded, with each grade facilitating a slightly finer texture of fibre.

The fibres were, therefore, transferred between each grade consecutively, before a desired texture was obtained. The precise nature of this mortar grading and the ways in which it operated in unknown. This process took between twelve and 36 hours to complete, depending on the texture of the type of textile being worked. Once this process was completed, the resulting pulp from the mortars was transfered into a large vat, which was attached to a charcoal heated stove.

Once within this vat, the pulp was continually agitated through stirring. A fine sieve was then used in order to mould the portions of the pulp into individual sheets. Each sheet was placed onto a corresponding ‘felt’ (composed of woollen cloth) and a stack of alternating sheets and felts was formed. This stack, or ‘post’, generally consisted of 144 pairs of sheets and felts. Once these posts were formed they were compressed in a screw press, which reduced the thickness of the post from around 600mm to approximately 150mm. The individual sheets could then be separated from their corresponding felts to be hung up and dried. These individual sheets, at this stage of the manufacturing process, took a form that could be described as paper.

Post-medieval Woollen Mill

By the 1860s, the paper mill at Melin Mynach was out of use and was purchased by William Lewis, a woollen manufacturer from Penllergaer to the east of Gorseinon. Lewis had converted the old paper mill into a woollen mill by 1875, a process which involved the construction of a new mill building.

The old paper mill was, however, retained rather than demolished and may have been used by Lewis as a weaving shed. The new mill building was three storeys in height with a large waterwheel on its northern end. This waterwheel was reconstructed in the 1990s. In terms of structure, the woollen mill was more robust than the previous paper mill and was constructed using roughly dressed sandstone blocks. Internally, the woollen mill was compartmentalised into four bays and the windows incorporated into its longitudinal east wall were markedly large in size, spanning both the ground and first floors of the building.

The precise operations being conducted within the woollen mill are difficult to determine, although it is likely, based on information from Lewis’ account books, that the interior was supplied with carding and scribbling machines. These same account books also indicate that William Lewis was supplying woollen flannel manufactured at the mill to the local markets of Swansea, as well as cloth for shirts and underclothing.  Attached to the southern end of the new mill building was the dyehouse, with passage between the two buildings being facilitated by a pair of parallel doorways. Beyond the dyehouse there exists evidence that the woollen mill witnessed further extension during the Lewis family’s proprietorship. These building extensions are presumed to have bee incorporated sometime after 1879. One of these extensions takes the form of a T-shaped building, single storey in height, with narrow sandstone footings. Another extension is situated approximately 13m of here and takes the form of another narrow single storeyed building. The precise function of these buildings has not yet been determined.

Selected Bibliography

Lawler, M, 1990, Melin Mynach, Gorseinon: Archaeology, History and Future Prospects, GGAT Report No 90/01.

Roberts, R, 2014, Cistercian Granges in Glamorgan and Gwent, GGAT Report No 2014/023.

Williams, DH, 2001, The Welsh Cistercians, Bodmin, MPG Books.

The Encyclopaedia of Diderot & d’Alembert, https://quod.lib.umich.edu/d/did/