Object: Mould (Bronze Age)
Period: Bronze Age to BRONZE AGE ( to )
Material: Copper alloy 
Found: Chinnor, South Oxfordshire, Oxfordshire (South East)
Discovery method: Metal detector
Description: A copper alloy Middle Bronze Age palstave mould formed of two interlocking halves (i.e. bivalve) was found on the 25th of February 2017. No other objects or details of the find context were reported. The two halves (valves) of the palstave mould are described separately below and have been labelled and referred to as 'Part A' and 'Part B' throughout.



Description: 



Soil still adheres to both parts of the bivalve mould (especially to 'Part B') but X-radiography has assisted in description of both parts.



Valve (Part A) 



A valve for a Middle Bronze Age palstave with semi-circular pouring/sprue cup (see Fig. 1). The internal surfaces are well finished (although soil still adheres). Three small rounded tendons (semi-circular in cross section) are raised c.2-3mm above the surface of the mould and are designed to interlock with the negative impressions (sockets) found on Part B (see below). There are two tendons on either side of the stop ridge and the third is located at the blade edge of the valve, approximately midway along the length of the blade. There is a relatively deep mid-rib in the centre of the blade (c.4-5mm) and some scoring to the septum surfaces (see Fig. 1).



On the exterior surface of the mould there are two small circular protrusions (or 'pellets') located at the blade end of the valve, approximately level with the corners of the palstave's cutting blade (see Fig. 2). There is an area of white speckled patina extending around the centre of the mould and in one or two isolated patches on the corner of the valve and at the pouring sprue end.



Within the soil from the valve were three small heavily corroded pellets of ?copper alloy (now bagged and stored separately), more work is required to analyse and understand these inclusions. Other, similar fragments can be seen in the soil that still adheres to the interior surface of the valve.



Damage: A crack runs through the valve and is most noticeable on the exterior surface of the valve. It is 60mm in length and widens towards the blade end of the mould (where it reaches a maximum width of c.1mm). This crack is likely to be ancient. Other fissures can be seen in the septum (running perpendicular to the longitudinal axis of the palstave impression) and can be seen on both the interior and exterior surfaces of the valve (compare Figs. 1 & 2). These cracks/fissures (and others) are identified in the X-Radiography images provided by Daniel O'Flynn (Scientist, The British Museum) (see Fig. 3 & 4). Radiography reveals that the crack on the blade edge extends to the mid-rib of the palstave mould impression.



Dimensions: Total length of valve: 212mm; Width of valve: 90mm (at the max. point of blade width); Width of valve (min.): 47mm; Width (at pouring cup terminal): 50.5mm; Height of pouring cup: 25mm; Length (pouring cup to stop-ridge): 77mm; Length (stop ridge to edge of blade): 104mm; Width (max. blade width): 70mm; Width (at stop ridge): 25mm; Weight: 1461g.



Valve (Part B) 



Description: A valve for a Middle Bronze Age palstave with semi-circular pouring sprue/cup. The pouring sprue/cup end of valve is eroded/worn, possibly through use prior to deposition. The interior surface of the valve has three corresponding sockets for the tendons of valve 'Part A' (see Fig. 1). There is a semi-circular indent in interior surface of the valve that has a depth of c.7mm. This may have function to enable the metalworker to separate the two valves easily following the casting process. Soil adheres to the surfaces of this valve more fully than Part A. But the X-Radiographic image demonstrates that the patterning is identical to Part A, as one would expect (Fig. 3-4). There are cracks running horizontally across the blade on either side of the valve. Radiography confirms that these do not meet. They are visible on the exterior and the interior surfaces of the mould.



The impression of the palstave has not been set as evenly within the valve, hence the distance between blade corners to edge of the mould is 10mm and 12mm in the case of 'Part A' but 6.5mm and 13mm in the case of 'Part B' (Fig. 1).



On the exterior surface the same white-speckled patina that features on the exterior of valve 'Part A' covers the middle section of the valve (Fig. 2). There is no equivalent to the pellets that are found on the corners of the exterior surface of 'Part A'.



Damage: Cracks can be seen through the blade, running through the mould but not extending across its full width. These cracks are likely to be ancient. X-Radiography (Fig. 4) reveals additional cracking within the septum of the palstave impression, running perpendicular to the longitudinal axis of the palstave impression and extending from the mid-rib to the edge of the blade.



Dimensions: Are as 'Part A' with a slightly heavier weight (1482g), probably due to the adherence of soil. The palstave impression sits less evenly within the surface area of the mould (as noted above).



Discussion:



This is only the tenth Middle Bronze Age palstave mould found in Britain to date and only the fourth example of a mould used to produce unlooped palstaves (Adams & Webley 2016, Table 1; A. Gwilt pers comm.). It is the first to have been found in Oxfordshire, if we exclude the palstave-chisel from Sutton Courtenay, Oxfordshire (Adams & Webley 2016, no. 47). Other palstave moulds have been found in Southern England, including examples from London, Norfolk, Shropshire and Wiltshire.



The mould would have been used to cast broad bladed palstaves of Rowland's (1976, 32-3) Class 3, Group 1. The mould is most similar to that from Deansfield/Danesfield, Gwynedd, Bangor, Wales (Adams & Webley 2016, no. 20; British Museum Reg. 1849, 0521.5). That mould also has two tendons on either side of one valve and would have been used to produce similarly formed palstaves of Class 3, Group 1 (Rowlands 1976, 32-3).



Two factors may account for the abandonment and/or deposition of the bivalve mould. Firstly, the two valves fit relatively snuggly at the blade end of the bivalve (as one would expect for the bivalve to function effectively) but there is a bowing of both valves at the pouring sprue/cups ends (Fig. 5). This would lead to spillage and miscasting and would be very difficult to correct or stimmy. Similar bowing of copper alloy moulds has been noted on modern (experimental) examples and has resulted in the failure of the mould to cast successfully (N. Burridge pers comm.). Secondly, the large cracks across both fragments (see Figs. 3-4) would create potential for leakage and failure to cast palstaves of adequate form for use.



Please note: further conservation work and scientific research would be highly desirable given the relative rarity of this find.



References: 



Adams, S. & Webley, L. 2016. 'Material Genealogies: Bronze Moulds and their Castings in Later Bronze Age Britain', Proceedings of the Prehistoric Society 82, 2016, 323-40.



Rowlands, M. J, 1976. The Production and Distribution of Metalwork in the Middle Bronze Age in Southern Britain, British Archaeological Report, 3 I (i & ii)
Notes: As a single find of two objects of prehistoric date, this find qualifies as Treasure under the stipulations of the Treasure Act (Designation Order 2002).
Subsequent action: Acquired by museum after being declared Treasure