What kind of signature would a finery forge or bloomery have? I would  
assume that the hammer scale would show up. But as the hearths in a  
finery forge or 17/18C bloomery are above ground what kind of a  
signature would they have?

I am particularly interested in references in the literature that I  
can get. So "gray literature", unless someone can send me copies, are  
probably not going to help.