Why were the ingots mostly round?

Rivkin · 10th April 2006, 07:05 PM

Quote:

Originally Posted by Jeff Pringle

I think the pattern difference above is a lighting artifact, with different lighting the pattern should look uniform across the surface.
Patterns in wootz come from the fact that when the steel starts to solidify, the first crystals 'want' to be pure iron/carbon - the impurities in the melt become concentrated in the areas of secondary crystalization, in between the networks of already solid metal. So the impurites do get localized to a degree.
Theoretically, you can control the grain orientation, and hence ultimate pattern, by manipulating the shape of the solidifying metal (by casting into a mold of varying thickness), but I don't think anyone is working on this yet.

Pattern's orientation is going to depend on the sample's size/shape if it is comparable to the grain's thickness, however imho since the interaction between particles here is a short range, the thickness of grains mostly going to depend on chemical composition of the sample.
What I was thinking is that if one locally introduces an impurity, preferrably such that an energy bonding to the pattern if favorable over bonding to the matrix, one can probably create really nice patterns, not very practical, but very nice indeed.

Jens Nordlunde · 10th April 2006, 09:35 PM

Jeff/Galvano, thank you for showing the ingots, I think they illustrate what you are describing.

Not all the iron ores could be used for ingots, and the Indians knew it. Some ores could only be used for tools while others could be used for weapons and ingots, maybe that is why some of the Arabian merchants had their own people stationed in India to check the ingots before they were exported. If I have understood you correctly, they could however not check if the ingots had ‘bubbles’ inside, and maybe not all cracks could be seen – or could they?

Jeff Pringle · 11th April 2006, 01:40 AM

If an ingot has a bad bubble problem, it usually is visible on the outside. Occasional small bubbles are easy to work around, so even if they can't be seen they are not a problem. Cracks that mean an ingot is no good usually show up right away, and in descriptions of historical ingot testing that I've read, that's the first thing they checked - how they responded to the first few hammer blows.
The ingot pictured above started cracking (in an ominous fashion) right away, but I kept at it to see if I could coax some useable metal out of it - no such luck!

Jens Nordlunde · 11th April 2006, 01:55 PM

Jeff, it is interesting what you write about the ingots. I have never, although it may sound strange, had an ingot in my hand. When I started to collect many years ago, there were not many for sale – but that has improved a lot in the last years, like discussed on another thread. I should have remembered the sound test, which can be used on metal, glass, porcelain and probably on many other things.

You write, “Occasional small bubbles are easy to work around, so even if they can't be seen they are not a problem.” Does this, ‘work around’ mean, that you cut the bubbles out when you have flattened the ingot? Or how do you ‘work around the problem’?

Jeff Pringle · 12th April 2006, 12:49 AM

The first way to work around bubbles is like an insurance policy - Usually the ingots have some porosity on one side, and you keep track of this side as you go from round to square, then make that side the back of the blade. This way they are far from the cutting edge and supported by more metal around them. I've seen old swords at auction with small seams on or near the back that are certainly the residue of ingot bubbles.
The other thing to do is to watch for the subsurface porosity to show up during the round-to-square forging and file/grind them out as needed. Any dips in the surface at this point in the process will be long gone by the time you get to the shape of a blade blank.

Rick · 12th April 2006, 01:41 AM

While we're discussing wootz ; I would like to dredge up a subject from the forum's past .
Once there was shown a sword with one side showing an active wootz pattern ; oddly enough though on the obverse the steel showed no pattern at all .
Any ideas on how this could have happened Jeff , or any other of our smiths ?

B.I · 12th April 2006, 08:44 AM

hi rick,
i have a historical opinion on this, as apposed to a metallurgical one.
for some reason, the wootz ingots were small, maybe too small to make a large blade. and so, a blade was made from different ingots joined together. this is why some indian blades have a 'scarf/lap' weld along the blades. also, why there is normally a join along the spine of all wootz blades, where ingots have been sandwiched together.
i am away from my notes, but i believe travernier mentioned this, when travelling with the moghuls in the 17thC. he said that each ingot was always cut in half, to determine the quality of the pattern. a good size sword was made from 3-4 of these halves.
occasionally, you will find a scarf weld, with one side being wootz and he other steel. even rarer, you will find one complete side being wootz, whilst the other is steel or even pattern welding. rarest of all, is both sides wootz, but sandwiched between a layer of steel (presuming it is steel as the colour seemed different). the last is a thick blade, of substantial quality.
the joining/sandwiching/scarfwelding is my theory, not traverniers. he just mentioned about the halves. during my collecting/studying i've heard many different theories about scarf welding, some pretty ridiculous (from stregthening to religious). this is one that i feel happy with, and think that travernier adds some fuel to it.

12th April 2006, 01:41 AM	#6
Rick Vikingsword Staff Join Date: Nov 2004 Posts: 6,336	Not A Threadjack But A Nagging Question While we're discussing wootz ; I would like to dredge up a subject from the forum's past . Once there was shown a sword with one side showing an active wootz pattern ; oddly enough though on the obverse the steel showed no pattern at all . Any ideas on how this could have happened Jeff , or any other of our smiths ?

10th April 2006, 09:35 PM	#2
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Jeff/Galvano, thank you for showing the ingots, I think they illustrate what you are describing. Not all the iron ores could be used for ingots, and the Indians knew it. Some ores could only be used for tools while others could be used for weapons and ingots, maybe that is why some of the Arabian merchants had their own people stationed in India to check the ingots before they were exported. If I have understood you correctly, they could however not check if the ingots had ‘bubbles’ inside, and maybe not all cracks could be seen – or could they?

11th April 2006, 01:40 AM	#3
Jeff Pringle Member Join Date: Nov 2005 Posts: 189	If an ingot has a bad bubble problem, it usually is visible on the outside. Occasional small bubbles are easy to work around, so even if they can't be seen they are not a problem. Cracks that mean an ingot is no good usually show up right away, and in descriptions of historical ingot testing that I've read, that's the first thing they checked - how they responded to the first few hammer blows. The ingot pictured above started cracking (in an ominous fashion) right away, but I kept at it to see if I could coax some useable metal out of it - no such luck!

11th April 2006, 01:55 PM	#4
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Jeff, it is interesting what you write about the ingots. I have never, although it may sound strange, had an ingot in my hand. When I started to collect many years ago, there were not many for sale – but that has improved a lot in the last years, like discussed on another thread. I should have remembered the sound test, which can be used on metal, glass, porcelain and probably on many other things. You write, “Occasional small bubbles are easy to work around, so even if they can't be seen they are not a problem.” Does this, ‘work around’ mean, that you cut the bubbles out when you have flattened the ingot? Or how do you ‘work around the problem’?

12th April 2006, 12:49 AM	#5
Jeff Pringle Member Join Date: Nov 2005 Posts: 189	The first way to work around bubbles is like an insurance policy - Usually the ingots have some porosity on one side, and you keep track of this side as you go from round to square, then make that side the back of the blade. This way they are far from the cutting edge and supported by more metal around them. I've seen old swords at auction with small seams on or near the back that are certainly the residue of ingot bubbles. The other thing to do is to watch for the subsurface porosity to show up during the round-to-square forging and file/grind them out as needed. Any dips in the surface at this point in the process will be long gone by the time you get to the shape of a blade blank.

12th April 2006, 08:44 AM	#7
B.I Member Join Date: Jan 2005 Posts: 485	hi rick, i have a historical opinion on this, as apposed to a metallurgical one. for some reason, the wootz ingots were small, maybe too small to make a large blade. and so, a blade was made from different ingots joined together. this is why some indian blades have a 'scarf/lap' weld along the blades. also, why there is normally a join along the spine of all wootz blades, where ingots have been sandwiched together. i am away from my notes, but i believe travernier mentioned this, when travelling with the moghuls in the 17thC. he said that each ingot was always cut in half, to determine the quality of the pattern. a good size sword was made from 3-4 of these halves. occasionally, you will find a scarf weld, with one side being wootz and he other steel. even rarer, you will find one complete side being wootz, whilst the other is steel or even pattern welding. rarest of all, is both sides wootz, but sandwiched between a layer of steel (presuming it is steel as the colour seemed different). the last is a thick blade, of substantial quality. the joining/sandwiching/scarfwelding is my theory, not traverniers. he just mentioned about the halves. during my collecting/studying i've heard many different theories about scarf welding, some pretty ridiculous (from stregthening to religious). this is one that i feel happy with, and think that travernier adds some fuel to it.