Exchanging Medieval Material Culture Studies on archaeology and ...

APPENDIX 1
Metallurgical analysis of the Bettws Newydd ewer
by Mary Davis
A drill sample was taken from the cast Bettws Newydd ewer
[nmw acc. no. 98.33H] using a 1mm drill aft er removal of corrosion
products from the surface in the drilled area; this sample
consisted of fi ne powder; a small metal scraping was also
taken from an area adjacent to the drill hole. Th e samples analysed
using a CamScan MaXim 2040 scanning electron microscope
(sem) with an Oxford Link Isis energy dispersive X-ray
spectrometer (sem-ed). Th e analyses were carried out on areas
of metallic copper alloy avoiding slag inclusions or corrosion
where present and therefore representing the content of the
copper phase.
Th e sample from Bettws Newydd was problematic, and the
results should be looked at with some caution; the analysis
showed widely variable lead levels (1-35%). Within leaded cop-
TabLE 1
Comparison of alloy compositions for ewers from Wales, by percentage
(* = data from Lewis et al 1987)
Tripod ewers from medieval households 165
per alloys, the lead usually occurs as small, fi nely dispersed
spherical globules scattered at the grain boundaries and within
the grains themselves. Th e drilled Bettws Newydd sample consisted
of fi ne metal fi lings, and here it was impossible to analyse
a relatively large area at one time; this resulted in lead
being either over represented where it had segregated, or under
represented where it was absent. Th e metal scraping probably
gave more accurate results, but these were also very variable.
A percentage range of both lead and copper totals from this
ewer are given in the table below, rather than an average reading
(table 1). Suitable methods for quantifi ably analysing this
type of sampled alloy (such as icp-ms) were not available for
this study. Th e sample from the Caerleon ewer spout was
clipped at a broken edge rather than drilled, and the results
from this piece are more representative.
Provenance %Fe %Cu %Zn %As %Sn %Pb
‘Kenfi g’* 0.8 79.3 6.23 0.33 2.19 10.2
‘Strata Florida’* 0.57 76.2 10.3 0.62 4.8 4.31
Llandefalle* 0.71 86.9 5.36 1.92 5.36 4.38
Corwen* 0.33 67.1 4.87 1.95 6.59 18.8
Criccieth* 0.79 75.4 7.41 0.39 5.58 8.1
Llanrwst* 0.51 80.8 9.49 0.58 9.49 6.65
Bettws Newydd 0.5 60-75 5.1 1.1 4.2 15-25