Originally Posted by Chris Evans
Sponge iron has to be hammered extensively every which way to reduce its slag contents (by squeezing it out)
However, I'll venture to question the presumed superiority (in the article) of a Wootz blade against one well made from sponge iron and hardened.
In a past thread we have discussed whether Wootz was quenched and tempered in the old days, and there is some evidence that some of it was. As to how they went about this and how successful it was I am not sure - Without having done any first hand experiments, or reading of any such attempts, my guess is that if high carbon Wootz is heated to the extent that a substantial amount of the carbides are dissolved, then upon quenching and tempering its microtructure would turn into a proverbial dog's breakfast with very uncertain mechanical properties.
Chris, I am confused by your words. I understand that old steels were made with bloomery iron, and not sponge iron. Or instead, decarburizing cast iron with high carbon content, which is more easily molten at lower temperatures. Sponge iron, as I understand it, is another kind of product. I feel much of the discussion about wootz is biased by speculations which tend to maximize, or instead, minimize, the value of this type of steel, making statements above of the facts. It is scientifically healthy to have some dose of scepticism in front of myths and distortions. But the fact is that we donīt have enough samples of wootz blades, studied and tested, and even less scientific comparisons among wootz blades and european blades from the same period. On the other side, it seems that there is another manuscript from Al Kindi dedicated to the thermal treatments of the blades made with wootz, which is not yet printed, though I understand maybe there is already an italian traslation. There are references to this work on the book Medieval Islamic Swords and Swordmaking
, by Hoyland & Gilmour.
But even with the publication of the translated manuscript, I belive we will yet have many questions for years to come about this subject. I hope the archaeometallurgy helps us in the progresive clarification of many of our questions. Other discoveries look ahead on the study of the traditional swords of the world, as the viking swords seem to demonstrate. I still believe the articles about viking swords refer to a relatively clean high carbon crucible steel, and not to wootz. The swedish article mentions the presence of 0,8% refined carbon steel in one of the edges of the studied sword, and 0,4 to 0,6% carbon steel on the other edge. This opens the possibility of speculate about some specialization among the different edges of the viking swords, or at least in some of them, but it is only a good? pretext to continue our conversation. Some of the viking swords seem to be very complex in their structure, not because they are multilaminated in the japanese way, but because they have many different types of steels and irons in their composition, all welded in the make of the blade.
This kind of solution is not less sofisticated, or work intensive, than the japanese nihonto, in my opinion, but this is said with no regard of the differences on their success to have the best relation metallurgy-geometry-design, or to do with more effciency the expected job, as it is another very difficult subject to discuss with some scientific basis. Of course, this are only some of my ideas, and I can be wrong.