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GernotP

antique wootz finish problem

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Hello,

As a first time poster a short introduction is probably in order. I am not a bladesmith, just a collector of antique bladed weapons. My main interest is in Indian and  Middle Eastern weapons, especially those made of wootz crucible steel, and started collecting about 2 years ago. Unfortunately there seems to have been quite a spike in interest in the last years, so high quality pieces in good condition are hard to come by for reasonable prices.

I have bought some pieces in reasonable condition and had some of them professionally restored with good results. But because shipping, restoration fees and customs issues (I am looking at you CITES) are a hinderance and since I had some prior experience with refinishing modern knifes I decided to give it a go myself.

I have purchased a moghul shamshir in rather terrible condition, which I was fully aware could not be restored to pristine state, at the beginning of last year, as a proof of concept or test bunny, however you want to see it.

before.jpg

 

 

After reading a lot and doing further experiments on old knife blades and after quite a few stops and starts I have finally finished repolishing it in the last days.

refinished.jpg

 

Etching revealed a beautiful persian style wootz pattern with signs of differential heat treatment of the edge. On one side however there are some lines parallel to the edge, that did not take the etching to the same degree, on the other side you can see a similar effect sight right along the edge (see added pictures).

nachher.jpg

 

nachher2.jpg

 

 

My question is, what went wrong here? I think I can rule out a problem with the etching, since I had to repeat it twice to get it right due to beginner errors and this problem persisted. Could it be a material error or did mess up the polish as in accidentally burnishing these parts of the blade if that is possible? Or anything else that I can't think of.

 

Thanks a lot for your help

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It is my experience, in modern patternwelded pieces, using modern materials, that what you're seeing is a heat treating issue.  It's is an area that is soft and it etches and blues differently than the surrounding material.

It could be a low carbon area, or an area that was under temperature.  It could be an area that was over thick.  It might even have been over heated at some point in it's life.  I know that in Japanese blades a hot copper block is sometimes applied to the spine to correct defects in the sori.

 

This is just my .02 (you'll have to adjust for international markets) and hopefully one of the wootz guys will weigh in with a better informed opinion.

Geoff

Very cool piece BTW

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Hi Geoff,

Thanks for the reply. A heat treatment issue too was an on my mind.

Honest question: I did all the polishing by hand, but still the blade became quite warm at times. When hand sanding could it be possible to generate too much friction to heat up the blade enough to mess up the heat treatment, especially at the edge where the area of contact between the sanding paper and the metal can become quite small?

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In my opinion it is inherent in the material; i do not think you could have changed the heat treatment by hand sanding. My opinion is free, so take it for what it is worth :)

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I agree with Steve.  Wootz does strange things, after all.  

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All right, then all that's left to do is refixing the hilt and I'm finally finished with it, and I can move on to other pieces with more potential.

Thank your for the input.

 

Gernot

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Nothing you did would have caused any real change to the heat treatment. Most likely..if it shows no pattern on the very edge...is that the blade got hot in the quench and all the carbides are dissolved and thus no or poorer pattern.

Ric

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On ‎11‎/‎19‎/‎2017 at 6:00 PM, Richard Furrer said:

Nothing you did would have caused any real change to the heat treatment. Most likely..if it shows no pattern on the very edge...is that the blade got hot in the quench and all the carbides are dissolved and thus no or poorer pattern.

Ric

Ric,

Do you think that the blade actually got quenched?  Could this have possibly happened by forging it too hot?

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possible, but not likely

Ric

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A few years late.... but it wasn't anything that you did in polishing of the blade.  The area along the entire blade edge where the pattern has dissolved is where the quenching of the blade has formed martinsite on the edge. This is common and expected to have the watered patterns at the edge be masked by the crystal structure of the blade.  Martinsite is harder than the Pearlite body of the sword, but the price you pay for the hardness is that the pattern shows less well or not at all.  Sword blades also are quenched to differing degrees due to their curve and that will affect the degree of martinsite that is formed in that place and the resulting hardness of the edge in that location.  This effect can be seen in a blade that is quenched very quickly, such as a water quench... not recommended at all..., making the whole blade martinsite and it can almost entirely obscure the pattern. Hope that helps.

Edited by Tim Mitchell

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