kogatana

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About kogatana

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  1. evfreek, Yes I meant quenching. It seems you have observed something very similar to what I have. Part of my piece was also silvery, it got dark covered with scale after I put it back into the fire. The spark test: I'm not expert, but by comparing the sparks on the hard end with those from other part, it is striking that the sparks on the hard part are totally different: the end of the sparks appeared somehow like many snow crystals, while on the other parts, nothing special, the bright rays were more like shooting stars: bright curved lines with no sparkling at the end. Bridgeport I have cut the hard part (one low quality hacksaw blade just lost all its teeth in the operation!), and thus had access to bare steel in the thickness of my piece. The bare steel was still very hard, so it was more than a crust. However my piece was quite thin (<1/8"), so maybe the whole thickness got "burned" as you said... But are you sure we can "burn" steel in a similar fashion as we can burn a dough crust?? Ludo
  2. It might be scale indeed, but I have cut about 1 inch of the cracked hard part, and when grinding the cut it is still hard. Why is scale so hard?
  3. How can a part of a piece of mild steel becomes hard without me tempering it?? More details: I took that piece of mild steel from an old metal fence in a farm. I believe it is mild steel, and very mild for that because it bends veery easily, is cut with my hack saw very easily and a file bites in it like teeth in butter. Now I make a nice hot charcoal fire, put there my 1" by 1/4" section of material, and taking it out after some time I notice that it looks as if it had melted. I do not pay much attention, though I'm a bit surprised since I've got red hot steel or iron before but never melted iron. Maybe this was only a partial melt, on the surface. Back home (I do not forge at home, I'd bother the neighbours), I want to get rid of that ugly end on my small knife. It is then that I notice that it is very very hard, definitely much harder than the remaining of the knife (and it is the side opposite to the edge). I do a spark test, and well, definitely the sparks are way different at that end compared to other parts of the knife. It rings differently also. I haven't quenched any part of the knife yet. Could it be that some carbon went into the material when it was hotter that usual and made a small area a high carbon steel? Otherwise how come did it become so hard? Ludo
  4. Now if I get a piece of very rusty and pitted iron that I want to forge: will the rust burn in the fire? Or do I need to have a really clean surface prior to heat? Ludo
  5. Thank you all. Thomas, I'm just trying to first understand what's flux and how to use it. That's the textbook and IForgeIron part. Next is to put into practice the information gathered which will be another story. I plan to forge weld to make a small knife or woodworking tool. Ludo
  6. Have you ever tried a forge welding using sand as a flux? I'm just reading in the book "forging" from J. Jernberg that this is possible, and that borax is a substitute for flux. Interesting anyway. What act as a flux in the sand, is it silica? Ludo PS: I read further, and you might be interested to know that borax can be heated red hot (I believe you put it in a pan on a stove) and left to cool. It become vitrous and have almost all of its water gone. In the form of powder, that "dry" borax won't boil when heated in the forge and will remain more easily on the pieces to weld.
  7. Thomas, interesting! I'd be interested to know where you got your iron ore and to read you if you have posted your experiences with the smelting. Could you post a link to the company's web you mention?
  8. Woody, does mild steel only bend without breaking when repeatedly bent? On the picture of my first post of this thread, you see a 1mm deep saw mark: without first sawing the bar, it would not break after 5 solid minutes of repeated bending. To make sure of the metal, I'll try the quenching and file method. Thomas, yes, 20 years is not old. And I also tend to think that what I've got is the result of a mix of various irons and steels. Bruce, I've just noticed you are from the UK. Here is a picture of wrought iron bars (that I'm sure it is WI), from a bridge made in the 19th century in Japan, from british iron. The picture was taken in the shop of a plane blade maker in Miki-city Japan. Steel and iron from England is widely used by Japanese woodworking tool makers. Also, an anchor and the chain, from unknown origin, also wrought iron and from another Japanese toolmaker.
  9. Thomas, I'll try that. Let me find some nitric acid... I'll keep you all updated. Ludo
  10. Woody, the piece come from an old fence, used now to build a shelter for chickens. According to my stepfather who owns both the chickens and the fence, it is some 20years old. I will try to do something out of that bar. Thomas and evfreek, you seem to confirm my first idea that it is not wrough iron indeed. evfreek, I like the idea of observing the crystals of the metal following the hints you provide, in Japan there is a quaterly about woodworking and tools that regularly shows pictures of various steels' crystalin structure used for toolmaking. Pictures are taken with just a simple optical microscope. By the way, what should I do with the rust? Put it as is in the forge's fire after some rough cleaning with a wire brush? Ludo
  11. I have found a source of what I believe is iron, now what kind of iron, I would need your help. Can we have an idea of the iron (or more generally the steel) by looking at the way it rusts: is there any particular rusting pattern for a given iron/steel? Now if we break the piece, by repeated back and forth movements, and observe the fracture, I'm sure we can tell something about the iron/steel. Not a precise metalurgical analysis sure, but maybe a rough idea of the metal, and how it would look like when etched for example Recently I watched a show about an archeological metalurgist who uses a microscope to identify the crystaline structure of an iron/steel and then date it. Here are 2 pictures. One shows the rust, with pits as deep as about 1/16" or 2mm. The other is a close up on the break, and the sawn area. Is this what one call wrought iron? I think I can say no, I've seen broken wrought iron and it looked more fibrous than this. Ludo
  12. Bonjour de Taiwan, Louise A forge made entirely out of brick is surely possible to build. On my small forge based on a BBQ, I use bricks, see: forge_brick_30.JPG (image) You could easily build a similar small forge only with bricks. As for stones, I'd be carefull on which one to use (or wouldn't use any at all at least not anywhere near the heat) as they might explode due to the heat. For the bricks, I haven't had any problem. Comment aimez-vous la France? Ludo
  13. I'll check the exact nature of that coal tonight (it's the morning now in Taiwan), will break a piece or two and take close-ups. I haven't got clinker for sure. The little amount of what I thought was burnt out coal that I've thrown away, I can still take it back to the fire! It's not gone yet.
  14. Should the coal burn completely, reducing itself to ash? I have never got ash with the coal. So maybe I've thrown away some (not much) coal that could still be burnt! What is clinker exactly? Does it look as if chunks of coal had melted together? If so, I didn't see this in my forge. Ludo
  15. The article is online. Link to the pictures: View of the blower (air admission has since then changed). FirstBlow_30.JPG (image) Combustible and partial view of the new air admission (I hope you could identify what type of coal I'm using). Forge_w_coal_30.JPG (image) Latest configuration: forge_brick_30.JPG (image) Ludo