wootz with interesting "striping"

[RSWORD]

This is an interesting example in that the wootz pattern has "striping" throughout the patterning. I would be interested in what is causing this.

[Jeff Pringle]

I think those lines are the remnants of the primary dendrites, the first steel crystals to solidify from the melt. If the melted steel is cooling very slowly through the liquid/solid transition, the 'trees' can get pretty big. They make it through the forging process to one degree or another depending on size, how much elongation happens and if the ingot is heat treated to diffuse the alloy content or not.
Figure 1c on page twelve of Figiel's "On Damascus Steel" shows an etched ingot, the dark lines you see on that face are the primary dendrites.
I'll see if I have a photo to post...

[RSWORD]

Jeff,

I have a copy of Figiel's book and see what you are speaking of. It makes for an interesting feature to a wootz blade. Structurally, any disadvantage to having too many "trees".

[Jeff Pringle]

Structurally, any disadvantage to having too many "trees"

No, I suspect they have no effect on the blade's structural state, too small in relation to the blade's cross section. Since the first steel to solidify is most pure, it would also tend to be the least brittle in the finished blade, so if there was an effect it would be towards increased toughness. Since the carbides don't collect in them, they might cause microscopic dull spots on the edge? Probably not significant to overall edge performance.