Object: Mould (Bronze Age)
Period: Bronze Age to BRONZE AGE (-1400 to -1200)
Material: Copper alloy 
Found: Penderry, Swansea, Swansea (Wales)
Discovery method: Metal detector
Length: 197 mm
Diameter: 43 mm
Thickness: 14 mm
Weight: 510.8 g
Description: Middle Bronze Age bronze mould for casting palstaves of Group III, Low Flanged Type of Taunton Metalworking Industry and probably dated to c. 1400 - 1200BC

The mould is represented by one valve of the pair, with a fragment missing from its base (blade end) (with a length of 197mm and a weight of 510.8g). The mouth (with a thickness of 14mm) is flat on its top surface and is damaged on one side. The exterior of the mould was circular-sectioned at its apex (with a diameter of 43.0mm) becoming hexagonal-sectioned at the neck, which has near straight and parallel sides as far as the position of the loop, where the sides have a rounded swelling, pronounced on the loop side but also present, although subtle on the unlooped side (reaching a maximum width of 54.8mm). The front of the mould has a prominent central groove along the neck (with a maximum depth of 9mm) and corresponding with the septum between the flanges. The mould half reaches a maximum thickness (of 24mm) at the position of the stop. The lower part of the exterior was also hexagonally-sectioned, with straight sides diverging to the base. The basal edge has largely been lost (with a surviving maximum width of 75mm) but appears to have had a gentle curved edge and has a bevel from the face to the edge (9mm thick). The blade part of the exterior was decorated with three divergent ribs, which extended to the basal edge. The surviving part of the basal edge, above the bevel is also enhanced with a rib as is the top of the side bevels. There is a chevron moulding on one side, corresponding with position of the loop.

The interior of the mould has a rounded channel at the apex as a reservoir for the molten bronze (11mm diameter and 26mm deep) feeding into the butt of the palstave. The flat top, where the two mould halves meet is of variable width (from 8.2mm ay the butt and the blade tips and 14.5mm below the loop) and has four locating sockets, to engage with tenons from the missing mould valve. The sockets are of lentoid form (18mm long, 5mm wide and 3mm deep) and with a pair located flanking the butt and a pair beneath the top of the blade. The palstave negative has gently convex sides to the upper part (with a maximum width above the stop of 24.5mm) and the flanges appear to gradually deepen, reaching their maximum height at the stop (where the mould has a depth of 14.4mm). The loop (22mm long, 11 wide, with a mould depth of 5mm and where the palstave has a width of 19mm) is positioned immediately below the stop at its lower end. The stop has a slight curvature. The sides of the blade are curved and divergent to the blade tips, one of which is missing (with a maximum surviving width of 59mm, and the mould has a depth of 2.3mm at the blade edge).The sides of the blade are perpendicular to the blade face, which appear to be moderately flat across its length and width but gradually becomes shallower. There is the suggestion of a groove running along the edge of the blade, perhaps indicating a subtle rib running along the palstave blade edge. The palstave blade would have been decorated with midrib (with a length of 65mm), beginning at the stop. There is an oval casting flaw depression (7mm x 5mm and 1.6mm deep) on the blade, slightly above one of the blade tips.

The interior and exterior faces of the mould have differing corrosion deposits or patinas, the exterior face has a pale brown corrosion deposit which has a tendency to flake off, revealing a pale, 'olive-green' patina. The interior surface has the same or similar brown corrosion over one side and the jet reservoir but elsewhere has a darker-green to black patina. Most of the scratches and striations inside the mould appear to cut through the patina and are likely to be more recent. There is a crack extending from the break on the blade to the side edge, consolidated at Amgueddfa Cymru prior to recording. Palstave moulds are commonly broken across their base or basal corners and Adams (pers. Comm.) has speculated about the possibility of deliberate damage across this area of the mould but suggests that the base is more likely to be a weaker area more susceptible to damage.

The mould would appear to have cast palstaves of Group III, Low Flanged (broad blade) type with a midrib, possibly of Type Sleaford or Type Harlech. The suggested grooves along the sides of the blade may suggest flange extensions, characteristic of Type Sleaford (Schmidt & Burgess, 1981, p133) . Sleaford palstaves are seen as beginning early in the life of broad blade palstaves with an uncertain longevity (ibid.). Broad Blade palstaves are traditionally dated to the Taunton phase of the Middle Bronze Age in Britain, corresponding to Needham's (1996) Period 5, dated to c. 1500 - 1150BC.

Only one other bronze palstave mould find is know from Wales, recovered from Deansfield near Bangor, Gwynedd, which comprised two mould pairs for a looped and unlooped palstave of Middle Bronze Age date. Webley and Adams' (2016) study lists eleven palstave mould finds recorded from Britain, including two locations with associated sets of mould pairs (Deansfield and Hempnall, Norfolk) and nine of which include both valves. Five of the palstave mould finds (from four separate finds) are looped and of Middle Bronze Age date, recovered from London, Deansfield (Gwynedd), two pairs from Hepmall (Norfolk),) and South Wiltshire. Of these finds, only the London mould valve was not decorated on the exterior. An additional palstave mould was recovered from Marton in Shropshire but with no detail recorded. Webley and Adams (2016, p. 324) noted that Later Prehistoric mould finds were absent in South Wales at that time. There has been little recorded Middle Bronze Age activity in the area around the findspot and the suggestion of contemporary metalworking is a significant new addition to our understanding of the Bronze Age of the area.
Notes: Metallurgical Analysis of the mould

By Phil Parkes



The bronze palstave mould was analysed using SEM-EDX and XRF analysis to determine metal composition. XRF analysis on the interior and exterior of the mould showed the two surfaces to contain the same elements with slightly different proportions, most likely due to surface depletion / enrichment due to corrosion. SEM-EDX analysis was carried out on a sample taken from the broken edge of the mould using a small hand drill to remove surface corrosion and extract flakes of the uncorroded metal. The analysis showed a bronze (83% copper and 15% tin) with small amounts of lead (0.5%), arsenic (0.8%) and nickel (0.5%) present.



There are clear differences in the composition of the core metal and the interior patinated surface confirmed by both SEM and XRF analysis which are due to surface enrichment effects.



The bronze mould has a number of small areas where a white substance, thought to be a modern clay used to take a cast from the mould, remains. A sample of the modern clay was compared to a sample of the white material removed from the mould for analysis by SEM-EDX. The results show that the two substances are the same (Figure 6) and consist of a fibrous clay-based material with a calcium sulphate (CaSO4) filler.



Average    Range     Average           Range

Nickel        0.5%       0.5-0.5%          0.3% 0-0.5%

Copper      83.4%     78.4-86.3%      38.1% 28.9-44.6%

Arsenic      0.8%       0.6-0.9%          4.9% 4.0-5.9%

Tin             14.8%     12.2-19.5%      54.5% 48.9-62.8%

Lead          0.5%        0-0.7% 2.2%   2.0-2.4%

SEM-EDX analysis of core sample and surface of interior of mould.
Subsequent action: Returned to finder