The secret of Damascus Swords was in the fact of how their metal was made. . . The hammer welding of iron wire with repeated reheating in a charcoal forge had the effect of incorporating minute amounts of carbon in the iron with the iron wires that were hammer welded. As you may know, carbon added to iron alloys makes steel, which was much stronger than the iron blades of other techniques of the time. Too much reheating and hammering and the blade became brittle, to little and it was no better than iron, wouldn't take and hold an edge, and would fail. The secret was knowing when to stop, when enough had been done for each sword. The wires were welded together by both forging at low temperature and the physical force of the hammering. It made a ply type laminate structure as well of stronger and springier steel.
The appearance of the Damascene metal was unique due to the patterns of each swordsmith's style of curling the wires.
Unfortunately, the system also incorporated impururities which resulted in the failure modes of the metal as it aged. . . Points of oxidation would form and crystallization of the metal weakening the blade over time and flexation causing them to go brittle with age. This is the same problem that makes Damascus barrel shotguns inherently unsafe no matter how good the barrel looks on the outside, it may be too brittle on the inside to handle even weak loads because age and internal corrosion has taken a toll.
The only better system for making swords was that of the Japanese who better understood the physics of the process and the nature of the sword metals with the number of folds they had given each incorporating various amounts of charcoal in each. The very best would have seven different types of steel in the blade. I have a Tanto (short blade dagger or sword) in my collection which was made by one of the finest swordsmiths in Japan who founded a major school or style of sword making. He was last known to be making swords in 1060 AD, so my blade is over a thousand years old.
The swordsmith was so pleased with the blade when he finished it he signed it. What's more, he went on and commented on the tang, saying "On a good day in late summer," which means he was very pleased with the blade and essentially named it.
Forty some years ago, a Japanese appraiser valued it at over $50,000. It's not much to look at, it's in a plain bamboo case, but some of the rainbow case hardening colors are still on the blade to this day, and it's still razor sharp. You cannot touch the blade with bare fingers or it will turn black with rust where ever your fingers touched if not cleaned immediately.
The Japanese appraiser suggested I have it polished in Japan by one of their "Living National Treasures," a man who still made Samurai swords in the ancient techniques. He'd only charge me about $500 an inch or so to do it, but it would bring out the brilliant colors of the rainbow that are still there. He does it with talcum powder as an abrasive and spends about a day working on each inch per side. . .
But, the appraiser warned me, once the blade arrives in Japan, it can never be returned under Japanese law! I'd be permitted to continue to own it, but I'd be required to place it on permanent loan to a Japanese cultural heritage organization of my choice in Japan. . . but polishing it, he assured me, would instantly double or maybe even triple its value! Whoopie duck. I declined.
That’s some amazing information! And quite an artifact you have!
I’d read in places about how some hero’s sword “broke” and wondered how that could happen. Now I know: poorly made and kept blades will certainly break thanks to inherent and introduced weaknesses. But even great ones can become brittle with time.
Facinating. Great comment.
Really cool story.
L