Dear Michael,
 
Let me add a reference which may post-date David Rotenstein's last list
revision:
David L. Halpin and Paul P. Kriesa
1997 The Benjamin Brownfield Site (11CH357).  Public Service Archaeology
Program, Research Report No. 34. Department of Anthroplogy, University of
Illinios, 109 Davenport Hall, 607 South Mathews Ave., Urbana, IL 61801.
 
Lester Ross raises some interesting points about the relation of techniques
and changes in material in the late 19th early 20th centuries.  Problems
certainly arise when working with alloys of unknown constituents.  But these
are more likely to be encountered in fairly specialized tools like lathe or
milling machine cutters or stone quarrying or mining tools.  But mild steel
and wrought iron can be dealt with using the same techniques as long as the
characteristic of redshortness is taken into account, that is, as long as
you work wrought at a high enough temperature.  In many repects mild steel
is more forgiving to work with than wrought iron.  Daybooks, material orders
and account books from 19th/20th century shops in the collections here don't
show any use of exotic steels in the work done in small town/agricultural
blacksmith work.  And the diary of Thomas Hazard, an 18th/19th century
b'smith in Rhode Island records a number of "failures" and repeated attempts
to complete a particular job.
 
When the staff of this museum removed the remaining artifacts from an early
20th century shop, an "above ground excavation" if you will, we found
"stratigraphy" in tool racks with forging implements near the wall and
engine repair tools closer to the outside.
 
Good Luck,
 
Charles M. Keller
Collections Manager