Daniel,
        In your discussion I was surprised to see no mention of hammer-scale.
This is a mixture of flat flakes of iron oxide shed from the metal as it
is heated and cooled, and spherical particles formed by  the
solidification during flight of the spray of molten iron oxide (plus
flux if used) formed when the work piece is struck by the hammer. As the
temperature of the work piece needs to at or close to the melting
temperature of iron oxide, a high proportion of spherical hammer scale
is indicative of welding rather than simple forging.  Normally,
hammer-scale predominates around the anvil compared with the hearth area
which has a higher proportion of slag and clinker. A number of studies
on Medieval site in Britain have been able to locate the anvil locations
on the basis of debris studies. The first being Gerry McDonnell's study
of the forge at Durton Basset Warwickshire, but unfortunately, I have
not seen a good British study of a post medieval smithy. This may be
because these have largely been considered as an inconvenience to be
cleared out of the way before getting to the 'real' archaeology.


--
Chris Salter,
Oxford Materials Characterisation Service,
&
Material Science-based Archaeology Group,
&
Electron Microscopy Research Support Group,
Oxford University Begbroke Science Park,
Sandy Lane, Yarnton, Oxford, OX5 1PF
Tel 01865 283722, EPMA 283741, Mobile 07776031608