Breck: I've done chemical composition on 3 Crolle samples and 1 Twist sample by Optical Emission Spectroscopy (OES), and they were non-standard AISI 1002 - 1005 low carbon steel. This would suggest that the iron component was wrought iron and the steel was very low carbon “mild” steel.
re: coloring. Steve Culver's thoughts are here
https://docs.google.com/document/d/1...g51u_SnEM/edit