[ajross]

Crucible steel techniques were always carefully guarded and never "public", but never really "lost". This stuff popped up regularly through history in various cultures, the Wootz smelters in south India were, I believe, still in operation when European colonizers were able to document the process. And by the mid 19th century it was fairly well understood by modern metallurgy.

It's just hard to do and requires a giant furnace. The folded stuff modern hobbyists are making looks almost the same and can be done in a propane forge.