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Post by larason2 on Mar 12, 2023 21:21:55 GMT
I'd like to try my hand at sand casting, and want to try to make the sword of Goujian. However, details on how it was made are scarce, and there's some contradictions (like Sword of Northshire's site). My best guess is differential casting and carving the mold, but I'm still pretty spotty on the details of those two things, especially how you go about patinating it. I'm pretty familiar with niage, so that will be my default unless I find out more about this casting stuff. I'd like to cut with it, and I don't think that cutting with a casted sword would work out well if I just ground the edge and didn't work harden. Does anyone know a bit more about it, or know where to point me? Thanks!
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Post by Turok on Mar 23, 2023 6:40:23 GMT
Hi larason2! Maybe you can ask rhema1313 of Rhema Creations. He specializes in ancient Roman weapons, but he has a lot of knowledge with sword making. Neil Burridge is another option to contact, and he focuses a lot on Bronze Age swords.
I wish I could be more helpful but bronze swords aren't my specialty.
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Post by larason2 on Mar 23, 2023 13:47:29 GMT
Thanks for your reply! I've asked around on other forums, and I think I'm closer to understanding what they did. Ford Hallam at the Nihonto Message board and Alan Longmire at the Bladesmith's forum were very helpful. What I think they did was carve the mold to accommodate metal pieces of different alloys, the 50/50 copper/tin for the blade, and the tin enriched surface cross hatch. Then, they casted as usual. I think they then treated with a sulfurous solution once it was polished to protect the surface, but I'm still looking into that! Thanks for the tips, I'll contact them!
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Post by zi on Nov 28, 2023 9:11:48 GMT
Thanks for your reply! I've asked around on other forums, and I think I'm closer to understanding what they did. Ford Hallam at the Nihonto Message board and Alan Longmire at the Bladesmith's forum were very helpful. What I think they did was carve the mold to accommodate metal pieces of different alloys, the 50/50 copper/tin for the blade, and the tin enriched surface cross hatch. Then, they casted as usual. I think they then treated with a sulfurous solution once it was polished to protect the surface, but I'm still looking into that! Thanks for the tips, I'll contact them! I think…For the Chinese bronze sword (770~256 BC)…Not considering local segregation of Sn element,the tin content is approximately 15% in blade, never exceed 20%....... It may also contain a few lead for liquidity(0%~10%).
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Post by larason2 on Nov 28, 2023 15:28:51 GMT
Yes, you're right. So, to make it, you have to cast three different alloys. For the blade (spine), it's 83% copper, 15% tin 1% lead and 1% iron. For the blade edge, it's 41% copper, 43% tin, 6% lead, 4% iron, 6% sulfur. For the cross hatch pattern on the blade, 68% copper, 29% tin, 1% lead, 1% iron, 1 % sulfur. The blade edges you cast as a thin strip, and the cross hatch pattern cast as a flat sheet. Then the flat sheet is cut by hand into the diamonds you see on the guojian sword. Then you make the sword mold out of casting sand, and carve out the mold and put into the carved sides of the mold the sheet/strips that you cast before. Then you cast the blade (spine) into the mold. Then the other alloys will be integrated into the blade/spine. This is called "differential casting," and is apparently how a lot of bronze age swords were made.
By the way, thanks for the nice pictures above, that's very helpful! I wasn't able to get the original papers for the research above, and I couldn't find a good picture for how the guard and the blade fit together! The sword shown above doesn't have the cross hatch pattern of the Guojian sword, but I would presume it does have the high tin edge.
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Post by zi on Nov 29, 2023 2:16:56 GMT
Yes, you're right. So, to make it, you have to cast three different alloys. For the blade (spine), it's 83% copper, 15% tin 1% lead and 1% iron. For the blade edge, it's 41% copper, 43% tin, 6% lead, 4% iron, 6% sulfur. For the cross hatch pattern on the blade, 68% copper, 29% tin, 1% lead, 1% iron, 1 % sulfur. The blade edges you cast as a thin strip, and the cross hatch pattern cast as a flat sheet. Then the flat sheet is cut by hand into the diamonds you see on the guojian sword. Then you make the sword mold out of casting sand, and carve out the mold and put into the carved sides of the mold the sheet/strips that you cast before. Then you cast the blade (spine) into the mold. Then the other alloys will be integrated into the blade/spine. This is called "differential casting," and is apparently how a lot of bronze age swords were made. By the way, thanks for the nice pictures above, that's very helpful! I wasn't able to get the original papers for the research above, and I couldn't find a good picture for how the guard and the blade fit together! The sword shown above doesn't have the cross hatch pattern of the Guojian sword, but I would presume it does have the high tin edge. en……you know……It did happen that the blades were cast from different metals , but the sword of king Goujian was not. The situation you're talking about is called "bimetal Bronze sword of Warring States”. It looks like this:
the tin never exceed 20% in bronze of edges except burial object. and the contains less than 10% or even 5% in keel. The table posted before shows the proportion of the main parts of the king Goujian sword. Tin content:18.8% in blade, 15.2%~29.1% in plaid, 29.6%~42.6% in guard。 In addition,let me show you an interesting photo that is very rare on the Internet. The remains of an encient sword grip. You can clearly see what is the ramie rope wrapped around the wooden part
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Post by larason2 on Nov 29, 2023 3:04:19 GMT
That's interesting, thanks! If differential casting wasn't used, then how did they get all those different tin, lead, iron and sulfur concentrations on the sword? I can't think of any other way to do it. Once you melt copper, any added metals are equally distributed.
Edit: I see where it says 剑格正中, that's referring to the sword guard. On wikipedia, it says that's the sword edge! So clearly a mistranslation there. Still, I think the raised pattern on the sword face must have been differentially casted.
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Post by zi on Nov 29, 2023 3:17:49 GMT
That's interesting, thanks! If differential casting wasn't used, then how did they get all those different tin, lead, iron and sulfur concentrations on the sword? I can't think of any other way to do it. Once you melt copper, any added metals are equally distributed.
Edit: I see where it says 剑格正中, that's referring to the sword guard. On wikipedia, it says that's the sword edge! So clearly a mistranslation there. Still, I think the raised pattern on the sword face must have been differentially casted. Segregation
Because the melting points are different,tin will accumulate in places where it cools quickly (thin areas) .All you need to do is minimize the amount of sanding,save the high tin parts
btw: The composition of the guard varies greatly, most likely because There's probably a little bit of welding flux left. Geometric pits on the guard, originally inlaid/brazedwith gold and turquoise
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Post by larason2 on Nov 29, 2023 3:32:38 GMT
Ah, that's helpful. Thanks! So they just carved the mold to get the pattern on it then. Given that, I'm guessing the sulfur was also a small amount in the copper, and ended up on the edges as well, or do you know if they used some kind of chemical to patinate the sword?
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Post by zi on Nov 29, 2023 3:57:19 GMT
Ah, that's helpful. Thanks! So they just carved the mold to get the pattern on it then. Given that, I'm guessing the sulfur was also a small amount in the copper, and ended up on the edges as well, or do you know if they used some kind of chemical to patinate the sword? yep, I once saw a documentary that detailed how to do the surface treatment on king Goujian sword……
I remember that there are two ways to achieve the desired effect.
The physical method is to fill the grooves with additional alloy powder mixed with a flammable adhesive(The traditional Chinese recipe is the liquid from the boiled bletilla tuber) and heat up.then you'll get the plaid you want.
Chemical methods.....Ah!I remember now. High temperature diffusion method by tin amalgam. It is likely that the black color comes not only from tin, but also from additional metallic mercury diffused into the bronze
i think you r right. The new view is that, sulfide doesn't protect bronze any better, may even be easier to make it dull. Sulfur is probably a flaw in early metallurgical techniques that were not good enough.
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Post by larason2 on Nov 29, 2023 21:57:22 GMT
Thanks, that's helpful. I don't have the equipment to safely work with mercury, so I think when I try my hand at this, I'll mix some powdered metal, flour for flux, and water and use that to coat the edges of the mold that I want darkened, and cast all at once. The other alternative is to test different patinators like liver of sulfur and see if I can get something close!
Last summer I practiced casting different alloys, but I didn't have enough sand to cast the swords I wanted. I have a mold I carved of a european bronze age sword, but this winter I hope to also make a mold for the sword of guojian! That picture of the handle is very interesting, almost looks like a Japanese sword with the wrap and the menuki on wood.
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