E. Heuse-Lemoine of Liege wrote in 1884 that the pattern coloring and contrast was dependent on the source of the coal, the source of the iron (and alloys present in the steel), and whether charcoal, coke, or coal was used by the smelter. And of course the chemicals then used for blacking.
The steel in twist and crolle was very low carbon, and it may be that after the 1880 the steel used in Laminated Steel had a higher carbon content. Higher carbon usually stains blacker, and it has been suggested that higher levels of manganese in the very low carbon steel yield a darker black also.

After church I'll post some 'befores and afters' of refinished "black & white" Laminated Steel - some with impressive contrast and others without.

This is a c. 1875 P. Webley & Son refinished by Craig Smith with an interesting pattern, but which is slightly "muddy"

[Linked Image from photos.smugmug.com]

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