Rights Holder: West Yorkshire Archaeology Advisory Service
CC License:
Our images can be used under a CC BY attribution licence (unless stated otherwise).
Unique ID: SWYOR-B89422
Object type certainty: Certain
Workflow
status: Awaiting validation
A large piece of iron tap slag of uncertain date, probably Roman to Post Medieval, about AD 43 - 1600. It is dense, magnetic and black to purple in colour with some rusty patches. It forms a thick plate which is rough and irregular on the lower face and sides, with characteristic runs of solidified molten metal across the top face. Both ends of the piece are broken. In cross-section it is D shaped. Measurements are; length 1694mm, width 1035mm, thickness 453mm.
Tap-slag is slag that is 'tapped' from a bloomery furnace. This is carried out during smelting so as to allow the long continuance of the operation. An opening in the side of the furnace is opened to allow the liquid material to run out. It cools to a solid slag with marked flow lines. There were fewer bloomeries after the Medieval period. The presence of slag can indicate a bloomery site. The D shaped cross-section of this peiec probably indicates the shape of the channel through which the liquid slag ran.
Compare SWYOR-26DAE7 and also see https://historicengland.org.uk/images-books/publications/archaeometallurgy-guidelines-best-practice/heag003-archaeometallurgy-guidelines/ especially figure 16 and figure 25. Puddling furnaces used from the 1790s to 1960s also produce tap slag of similar appearance, but the location of the find makes this date less likely.
In theory, archaeomagnetic dating could be used to narrow down the date range of this find, but the Historic England Guidelines for Best Practice note that "Dating ironworking features can be challenging [...] Samples for archaeomagnetic dating should be taken by, or under the supervision of, a relevant specialist." Further advice would be needed to know if this piece was a suitable sample.
The piece recorded here is just one of many pieces that were recovered from the same location. It is reported that the farmer was exacavting the field, so the pieces are from fairly deep in the soil. After discovery they were moved and the present location of the rest is unknown. The farmer may still have it. This piece was recovered by a member of the local archaeology group as an example of the material.
Class: tap
Subsequent action after recording: Returned to finder
Broad period: UNKNOWN
Period from: ROMAN
Period to: POST MEDIEVAL
Date from: Circa AD 43
Date to: Circa AD 1600
Quantity: 1
Length: 1694 mm
Width: 1035 mm
Thickness: 453 mm
Weight: 1191 g
Date(s) of discovery: Friday 1st January 2010 - Monday 31st December 2012
This information is restricted for your access level.
Other reference: PAS form number 3797
4 Figure: SE4416
Four figure Latitude: 53.63867465
Four figure longitude: -1.33599158
1:25K map: SE4416
1:10K map: SE41NW
Grid reference source: From a paper map
Unmasked grid reference accurate to a 100 metre square.
No references cited so far.