Hello All,
How can a a bloom be anything but heterogeneous considering the
environment in which is is formed?
Air blasts are not constant, charcoal size causes air currents and
hot spots to vary which in turn causes various micro-environments of
reducing, carbonizing and neutral areas in contact with raw
ore,partially reduced ores as well as the bloom top and slags.
Add to this the act of slag and charge material with blocking tuyers
at somewhat random intervals and the effect of tapping the slag and
its chemistry effecting its viscosity and therefor how it flows from
and around the bloom (if at all).
Heterogeneity is the name of the game.
NOW..that said
The larger the bloom body the larger the opportunity for evenness
with iron, carbon content and slag content in certain areas, but
sorting the bloom is part of the technology as is bloom consolidation
and bar forging.
In my experience the inner,outer and sides of the bloom vary in
quality, chemistry and properties..sometimes greatly.
I do not believe a "single alloy" can be obtained even with modern
crucible or induction practice without a good intent.
To some extent bloom quality can be witnessed in the products made
from said blooms...what do the tools and weapons of the time
illustrate in microstructure?
Ric Furrer
Sturgeon Bay, WI
On Nov 7, 2009, at 1:48 PM, SR Rubinson wrote:
> Dear Archaeometallurgy Community,
>
> I am looking for information on the products of the Saxon/Viking
> Early Medieval bloomery furnaces. Specifically the aspects of the
> blooms such as the amount of slag left in the bloom and the
> heterogeneity of the alloys within the bloom. Was it possible to
> get single alloy blooms (i.e. ferritic blooms, steel blooms,
> etc.)? Were the Early Medieval blooms very slaggy?
>
> I have been lead to believe that the blooms of the period where
> heterogeneous and it was the job of the bloomsmith to separate out
> each of the alloys in to the single alloy bars that will be used by
> the blacksmiths. I don’t agree with this, but have not been able to
> find literature for or against this theory. Do any of you know of
> places I can look for information on Early Medieval blooms?
>
> Thank you,
> Samantha Rubinson
> PhD Archaeometallurgy
> AGS
> University of Bradford
>
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