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Am I wrong?

  1. Aug 11, 2008 #1

    Evo

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    Yes, that's rhetorical, we all know I can't be wrong.

    I was just watching Anthony Bourdain on tv and they were discussing a Japanese knife maker. They said that the knife maker used a traditional charcoal fire in making the blade because he could control the heat better than with a gas flame.

    I don't see how that can be true. With a gas flame, you can keep it fairly constant. With a charcoal fire the heat would constantly fluctuate. You can also immedieately change a gas flame so that you can go up or down in temperature. You cannot do this with a charcoal fire. There is just no way you can achieve the accuracy and consistency of a charcoal fire in comparison with gas.

    Am I wrong?
     
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  3. Aug 11, 2008 #2

    lisab

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    I say you're right. Not only can you control the amount fuel on a moment's notice with gas, but the variability of charcoal must be much greater than that of natural gas.

    Maybe charcoal is just what he's used to - people hate change.
     
  4. Aug 11, 2008 #3
    It's tradition, and people tend to pay more for tradition than quality.
     
  5. Aug 12, 2008 #4
    That depends on how much practice he has using charcoal and how much practice he has using gas.

    Proficiency and experience with the tools that the person is using is probably a bigger factor than just the raw capability of the tools themselves.
     
  6. Aug 12, 2008 #5

    russ_watters

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    Perhaps it is a matter of the adiabatic flame temperature of gas being too high and people not making many devices to adjust the fuel-air mixture? He'd need a custom-designed furnace to do something he can do himself with charcoal.
     
  7. Aug 12, 2008 #6
    If you have a large pile of charcoal I'd say the internal temperature is probably pretty stable.
     
  8. Aug 12, 2008 #7

    vanesch

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    As grant said, this is more a matter of tradition and probably of experience. If this guy has inherited since 10 generations how to make good Japanese knives in charcoal, and has been doing it for more than 40 years, chances are that he can make very good knives that way, and moreover he's probably convinced there's some kind of chi or whatever half-magical force helping him forge the best of knives.
    If he has to alter about everything he knows, worships etc, and use a new technology, he'll probably won't be making good knives - and moreover he'd be convinced he'd make bad knives, denigrating his ancestors. So he won't probably even be motivated to improve upon knife making with gas.
    On the other hand, he can hardly confess that, so he needs to rationalize away his sticking to charcoal.
    Also, it might be that variable temperature is actually what is needed for a thermal treatment (annealing ?) of the steel.
     
  9. Aug 12, 2008 #8
    May also have to do with radiation heat of which charcoal fire has plenty of, while a gas flame works best by in direct contact by conduction.
     
  10. Aug 12, 2008 #9

    Kurdt

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    I think its because when hardening the blades the smith has to heat the sword slowly and carefully to achieve the correct structure changes of the metal. I don't think that could be achieved as well with gas. You'd probably heat it very quickly and not very uniformly.
     
  11. Aug 12, 2008 #10

    Moonbear

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    Plus it says HE can control the heat better with charcoal. That doesn't necessarily imply that charcoal is a more controllable heat, just that the smith is more familiar with it and better at working with it. Though, I was thinking along the lines of Kurdt's point too, that it might be the rate of heating. And, I'm not sure if you can get much differences in temperatures of gas flames without a lot of tinkering with them. Perhaps even the gradient of temperatures across a bed of charcoal would be useful in this craft.
     
  12. Aug 12, 2008 #11
    I saw a Nova show about japanese sword making. At one point in the process they have to cover all the windows and turn off all the lights and the sword maker keeps pulling the sword out of the coals and putting it back in. He's looking for an exact shade of orange. That's probably much easier to control with a charcoal fire because he can add air to heat it up if he wants, and every part of the sword gets the same amount of heat. With gas you've only got the one temperature for the most part and the only way to not get the sword so hot is to lower the flame, so you can't really have a uniform temperature over the whole sword
     
    Last edited: Aug 12, 2008
  13. Aug 12, 2008 #12

    wolram

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    Is there some mysterious art that has been lost and modern day metal workers can not reproduce, i some how doubt it, it is just that mass production has taken over.
     
  14. Aug 12, 2008 #13

    turbo

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    If the knifemaker puts the blade in a bed of charcoal, he'll get even heating of the blade from the outside to the inside. One of the things that the Japanese have mastered is the construction of blades that are very hard (almost to the point of brittleness) on the outside with a core that is softer and more resistant to breakage. Maybe the knifemaker needs charcoal to pull this off.

    I have made a few knives using old blades. Get an old blade (saw blade, industrial blade of some type) and soften it so that it can be worked. Shape the new blade from the material, drill holes for mounting scales, etc, heat-treat, mount and sharpen. What's the hardest part to get right? Heat-treating, by far. I was using torches for heating, and it's very difficult to get consistent results that way. An older fellow I knew made knives using similar techniques, but he had an electrically-heated muffle furnace for heat-treating (he was also a goldsmith) and he got superior results.

    Edit: Here is the hardest-to-heat-treat knife I ever made. It's a simple trout-and-bird knife with micarta scales. I made the blade out of a piece of Hyde industrial blade (paper-machine tail cutter). The problem is that the blade is so slim that it was tough to get even heating. After MANY tries, I finally got a blade that is flexible like a stiff spring, with a hard edge that is tough to sharpen.
    [​IMG]
     
    Last edited: Aug 12, 2008
  15. Aug 12, 2008 #14

    Astronuc

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    The gas flame provides a constant temperature - in the flame. The matter however is to heat the workpiece which requires conduction of heat into the piece and the interaction between workpiece and flame may not be a controlled (constant) as that obtained by immersing the workpiece in a bed of hot charcoal.

    Charcoal also provides carbon to the iron, and it is the iron-carbides which provide hardness and wear resistance to iron. Knife and sword makers set the temperature to form martensite in the steel.

    I saw the NOVA program on sword making. It is an impressive art. We discussed it somewhere on PF.

    Here's an interesting site - http://www.knife-making-supplies.net/japanese-kitchen-knives.html

    http://www.knife-making-supplies.net/hardening-tempering-knife-blades.html
     
  16. Aug 12, 2008 #15

    Dale

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    One other thing that is definitely different with charcoal v gas combustion is that gas produces much more water vapor. I don't know if that would affect the construction of a knife or not.
     
  17. Aug 12, 2008 #16
    The thing about Japanese swords is that the metal is folded many times, so you can get a really sharp edge out of it, and also like turbo said, they are hard on the outside and softer on the inside, so that you can slice easy but not have it break as easily.

    Most people don't need that kind of quality and it would be pretty hard to mass produce.
     
  18. Aug 12, 2008 #17

    Kurdt

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    I was under the impression that the folding was only to make the steel used more homoginised, since the techniques to produce steel at the time left impurities and uneven carbon distribution throughout. By folding and hammering the metal many times the impurities were removed and the carbon content was distributed more evenly.
     
  19. Aug 12, 2008 #18
    I was grilling up some hot dogs and cheeseburgers (I heard that charcoal broiled hamburgers cause cancer, so I always add the cheese) and I had some sheet metal lying around so I figured why not see for myself. So I folded over the metal, beat it down, put it over the charcoal and repeated this process. I noticed that the flat surface of the metal was just right for flipping the burgers, so I picked it up. It turns out that the handle on a knife is there for more than just convenience when stabbing people. It also prevents your hand from heating evenly with the metal. To say that the metal was 144 degrees F would be a gross underestimate. Now I have a decoration on my palm like that guy in Indiana Jones and I am definitely digging in the wrong place.

    After I bandaged up my hand, I got out the gas grill. I sparked that baby up and let the sheet metal fly. This is the way to go folks. I was heating, folding, beating, and grilling with a very even and controllable heat. I had served the last red hot just as the knife was taking final form. I got too cocky though and when I flipped the knife with the spatula, it came down truely, but inconveniently on my foot, severing an otherwise perfectly good toe.

    I agree with Evo that gas is better. I can get by on nine toes OK, but the pain in my hand whenever I grasp anything is a show stopper.
     
  20. Aug 12, 2008 #19

    I remember that about carbon too----it may be something similar in that some materials are heat treated in different ways--some in oils, some in water, etc.
     
  21. Aug 12, 2008 #20
    You're also pounding in vast amounts of Chi.
     
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