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Craft & Industries: Non-Ferrous Metal-Working

Catherine Mortimer

Introduction

The lead-working waste was collected under 35 small find numbers and relates to a variety of metalworking activities. The total weight of material is less than 200g; many samples weighing less than 1g could not be weighed. The material is distributed in 26 contexts, mostly belonging within 16 features, of which the (relatively) large concentration in Period 3 pit F520 is notable.

Material types

Lead-working at the site included both hot-working and cold-working. Evidence for heating and casting lead-rich alloys is found in the various drops, dribbles and other casting waste. Within the casting waste, there is a noticeable division between rounded or droplet forms, and rough-surfaced, irregular forms. The rounded forms are more likely to have been formed by cooling in water, whereas the irregular forms are likely to have been where metal was dropped on the rough workshop floor. This may be a chance situation, but it is possible that the two material types represent two different activities, one involving deliberate, quick cooling of the item being worked on (potentially including soldering and tinning) and the other involving waste falling to the floor by chance, probably during casting. The rounded forms are 2-4mm in diameter, each individually weighing less than 1g. Find no 5268 is larger small find weighing 29g, which seems to comprise small droplets melted or corroded together. One of the larger rounded forms, Find no 2098, may have been pulled with tongs.

Cold-working at the site is represented by sheet metalworking of various types. Among the evidence are straight-sided slivers of various lengths and thicknesses which were cut from the edges of lead-rich sheet metal, probably using a sharp knife. One example (Find no 2155) clearly demonstrates that the metalworker was deliberately cutting thin strips from sheet metal to a roughly standardized width. Other strips from the site are comparable in size but detached from the parent sheet. These pieces may represent a preparatory stage, before use in any of a number of craft activities, for example, the strips could have been used as bindings, inlay strips or tiny weights or, through further heating and alloying, in preparing small quantities of solder or copper alloy. Other examples of trimmings do not seem to be straight-sided on both sides, and are often small and thin. It seems likely that they are trimmings from artefacts. Apart from these types of material, other lead-alloy sheet metal at the site was also folded and worked. Some of this was probably done prior to re-melting and/or re-alloying, for example, Find no 2092 was folded into a neat package. This made it easier to fit into a crucible and to add to a melt in small, quantifiable amounts. Other sheet metal was folded into other forms, for example, Find no 2128 is a rough slotted bar shape. The c.74 pieces of Find no 4596 include a tiny fragment of what may have been a punch-marked lead object. This could have been a product of the workshop, or just destined for re-melting with the other trimmings and casting waste found in this context.


Lead object 2092


Lead object 2155

Alloy type

Many of the items are likely to be lead-alloys, containing both lead and tin, and potentially other elements in lower quantities; it is not possible to tell which alloy is present without analysis. Previous analytical programmes indicate that there was some alloy selection according to use, for example, at Coppergate (Bayley 1992, 810-4). A range of metallurgical characteristics can be achieved by choosing, or making, different lead-tin alloys; for example, some alloys will be softer or more suitable for giving a 'tinned' coating.

Distribution

Some of the small find groups include several different material types, relating to both hot-working and cold-working, for example, Find no 2213 includes trimmings, sheet fragments and casting waste (both rounded and rough). This may mean that a single workshop carried out several activities, at roughly the same time. The low melting temperature of lead and its alloys means that a simple domestic-style fire could be used for hot-working, quite close to where cold-working was going on. It was noted at Coppergate (Mainman and Rogers 2000, 2479) that lead-working debris was quite widespread throughout the workshops, indicating that lead-working was a skill that many metalworkers might use.

Dates

The context dates range from Period 3 to Period 8, Anglian settlement through to Late Monastic industry. The greatest number (17) of small finds come from Period 3 (Anglian) contexts; of these, nine small finds come from contexts in pit F520. In Periods 3, 6 and 8, there are examples of each type of lead-working; only two samples come from Period 7 (Monastic Industry), both folded sheet metal waste.

Comparative material

Lead-working seems to have been a small component of the metalworking activity at Blue Bridge Lane, compared with ironworking. It is also notable that very little copper alloy waste was found at the site (two examples: Find no 4605 and Find no 5049), and there is no direct evidence for precious metalworking. This compares with Coppergate and Fishergate where a much wider range of metalworking evidence was found (Bayley 1992; McDonnell 1993).

In addition, many of the Blue Bridge Lane examples are very small, less than 1g in weight, and were recovered from soil samples. Weights for the Fishergate and Coppergate lead-working finds are not published, but the catalogue entries and illustrations suggest that that the lead-working evidence there was nearly always represented by larger pieces. This may reflect retrieval methods at the two sites, but could also indicate the type and scale of metalworking carried out.

Catalogue

Period 3 Anglian

Find no 2111 F164 C13412 fragments of casting waste, rough

Find no 2213 F520 C18204 trimmings 1-3mm thick; 3 sheet fragments; casting waste, droplet 10g; 21 pieces including rough and smoother blobs

Find no 2124 F13 C1144 casting waste in form of 'splat'

Find no 2164 F520 C2120 2 fragments of casting waste, one 'dribble', one 'splat' shape

Find no 2202 F520 C18202 fragments of trimming, thickness <1mm; pieces of casting waste, one a smooth blob, one rough

Find no 2209 F520 C1820 casting waste, rough

Find no 4099 F520 C1820 trimming about 2m thick; 3 casting waste, fragments in dribble form

Find no 4101 F520 C2129 casting waste, flattened dribble

Find no 4579 F381 C18512 or 3 trimmings; 13 pieces of casting waste, of which some are dribbles, some rough

Find no 4580 F520 C18201 trimming; casting waste, 6 spheres or droplet c. 3-4mm diameter; about 37 other tiny pieces

Find no 4582 F46 C1167 trimming?

Find no 4585 F13 C1143 sphere, diameter about 4mm, material type unclear

Find no 4602 F458 C2055 casting waste, rough, very small

Find no 4604 F520 C2120 trimming from sheet? Very smallFind no 4596 F520 C18205 fragments of trimming, 2-3mm thick; casting waste, of which 18 are spherical or droplet shaped (2-4mm diameter); 1 fragment possibly from a punch-marked object; about 50 assorted tiny pieces

Find no 5268 F381 C2049 lead waste, appears to be droplets melted/corroded together

Period 6 Early monastic settlement

Find no 2098 F278 C1474, blob, possibly pulled at one end with tongs

Find no 2107 C1371, trimming from c. 3mm thick sheet, 2g; sheet/waste frag 1g

Find no 2112 F150 C1334, casting waste, rough

Find no 2128 F44 C1164, sheet c.3mm thick, folded into strip/bar shape, leaving a slot shape, also bent, possible knife cuts on one side

Find no 2166 C1636, casting waste, rough

Find no 2180 C1636, 3 fragments of casting waste

Find no 2218 F268 C1634, 3 pieces of casting waste, rough

Periods 7 and 8 Monastic, and late monastic industry

Find no 2092 Pit F215 C1406, sheet c. 1.5mm thick, folded into a 'packet'

Find no 2095 C1433, sheet c. 1.5mm thick, folded to packet or tube shape

Find no 2108 F186 C1364, sheet c. 2mm thick, folded, possible toolmarks

Find no 4102 F245 C1548, trimming or possibly casting waste

Find no 2155 F245 C1542, sheet fragment c.2-3mm thick, with trimmings partly removed

Find no 2156 F245 C1542, trimming, cut from sheet, thinner towards edges, curled over, length >150mm, thickness = 3mm

Find no 2167 C1255 casting waste, rounded dribble

Find no 4577 F219 C1485 casting waste, rough

Find no 4584 F178 C1292 casting waste?

Find no 4588 F223 C1484 trimming, c. 2.5mm wide, 18mm long