An old secret

Discussion in 'Knives, Swords, and other bladed weapons' started by BrPio, Sep 4, 2013.

  1. BrPio

    BrPio .

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    Hi, I'v been in bladesmithing for about 20 years (started at 14) and I thought once and a while I'd share a few things I'v picked up over the years. Here's one.
    In my early 20's I got in contact with a master bladesmith of the Japanese forms (who wished to remain nameless). He was very open about teaching the "secrets" he knew. I learned a foolproof way of how to edge harden blades. It works best on simple carbon steels and even will harden mid to low carbon steel, does not need to be folded or laminated steel. The blade should be made strait and at cooling it will curve by itself. First, the clay, it is a mix of half red clay, half fine sand, and 1/20th ash. Mix until the consistency of cake frosting, (Mmm frosting) than coat the entire blade with a layer 1/4in thick. Then remove with your thumb the clay mix from alone the edge, making a wave pattern along the edge. Round off clay edges with your hand. Let dry for a week. Next heating and the cooling the blade. The cooling mix, add salt to warm water until a hardboiled egg will float in it.(remove the egg)The blade will be heated to a orange color, than held over the warm saltwater mix, when the color of the blade turns to a low red heat immediately dunk it in the water (edge first, not tip first). As it cools don't let go of the blade's tang, keep it edge down and don't let it turn to the side. You will see the blade bend down than curve up. Pull it out when there is no more bubbles coming out of the water. And the rest is simply cleaning the blade and polishing it. Using this method I made a sword from a cheap mid A36 steel that could cut 1/2in rebar and framing nails. Have fun. :D
     
  2. Will

    Will Thread Hijacker

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    Wow...it is really cool of you to share this information with us! These are secrets of the craft that take forever to learn (if they are learned at all). I would love to try this technique out, bladecrafting has always fascinated me.
     

  3. Otees

    Otees Another Member

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    Interesting. There are so many tricks to the trade with anything!! :)
     
  4. BeMahoney

    BeMahoney Builder of things

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    Thank You for sharing the secret!- Wish I had time to do taht right now.
    But I´m being forced to work!- With money!! :(
     
  5. Wanimator

    Wanimator Banned

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    I knew about the clay part curving it but I didn't know about the other tricks, thanks for the knowledge!
     
  6. Slagskimmer Mike

    Slagskimmer Mike thinks TBG smells better than roses

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    Thanks for sharing this with us.
    I have a small knife I shaped out and needs harden/temper. This post is well timed for me. Next time my buddy has the forge going I must try it out.

    The clay around here is sort of light brown, does that matter? One way to find out...
     
  7. Flipgun

    Flipgun Well-Known Member

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    So, edge first. When you say, "bend down." It bows up from edge to back. ?
     
  8. BrPio

    BrPio .

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    Yes edge first and I should of also said horizontal. And yes in 2 directions ending up curved back. That's how a real katana gets it's curve. It's not too important to watch, but fun to see. Like the steel has come to life in the water.
     
  9. Flipgun

    Flipgun Well-Known Member

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    Vertical actually. I had seen some vids but I wanted to be sure I understood. Thank You
     
  10. wbap

    wbap Member

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    very cool :)
     
  11. BrPio

    BrPio .

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    I assure you horizontal is better into a long brine bath. If the blade is dipped vertical, it will get soft spots and cracks with higher carbon or at the least an uneven temper on the edge. Because the amount of salt in the water changes pending on the depth, so if dipped vertical the tip of the blade will cool at a different rate than the base or tang.
     
  12. Flipgun

    Flipgun Well-Known Member

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    My mistake. I saw it going in flat to the side instead of what you said. Sorry!
     
  13. BrPio

    BrPio .

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    Also my falt. It's hard to explain some things with just words.