So a few years passed, and I got a few new insights to my initial question about cold iron. 4 years after the last time visiting this thread I started viking period of time reenacting, and therby got some new knowledge about classic ironworks. Therby I think I found what cold iron is (at least for me)
First a few requierments for the stuff:
Has to be rare
Has to be more or less low tec
The basic wrought iron thing dosn´t cut the mustard for me, so I am going a step further. Smelted Iron from a Bloomery
At a few occasions I worked the belows on such a furnance and listend to the smith. And therby get to know the basics of this kind of iron making. You produce Iron in this frunance ovens from iron ore ( basicly rust with mineral stuff around, take Bog Iron as an example) What makes this a good candidate for cold Iron is, that here the rust ist just reduced to iron but the iron itself always stays solid and never get liquid becous the temperture inside this process dosn´t get high enough to melt it down.
So here the pro points for my thesis:
Rare : Modern Iron making is a lot cheaper and easyier than the traditonal way. Acording to the friend of mine 1kg of smelted iron from a bloomery, ready for the normal smith takes 80 h of solid work.
Cold : In the process in a bloomery the Ironoxid and iron never gets above its melting point
What are youre thoughts on this?