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Toledo Steel


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Recently I heard about this. Supposedly they used to weld a billet of wrought iron into the middle of the sword, then once it was forged somehow harden using river mud and water. But my question is why the mud? Presumably these were all through hardened and not tempered (they were supposed to be harder than the average blade), so I can't think of any advantage to or need for using mud for heat treating.

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What is your source, and what does it actually say?  Without seeing it, it sounds a lot like "quenching in the blood of virgins" stories.  It makes some sense to have a low carbon core in a sword, even with carbon migration you'd have a core material that would not harden to any great degree.  Mud might give you some of the benefit of a clay mask quench, it's hard to see how river water would make much difference (mineral content, maybe?).  There is a lot of magic there, it's hard to separate fact from story.

 

Mike Bell (Dragonfly forge) gives a talk on Japanese sword forging myths.  One of the things he says is that his teacher told him that the only thing he required from the quench tank was that they knock the ice off it in the winter, temperature, water source, how you hold your mouth, none of it makes any difference.

 

There are stories about the use of urine as a mordant in dyeing.  The claim was made that the urine of pre-pubescent boys worked best ( the idea that pre-pubescent red heads was best is pure folklore).  Whether this is true, urine is used for a number of "industrial" processes.  Dyeing camp needs to be sited downwind whenever possible.  Another claim is that the urine of men who have been drinking red wine is best for the mixing of gun powder.  There is some truth to this, it gives the liquid a high PH, which assists in the dissolving  of the nitre compounds.

 

Geoff

 

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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Certain towns had reputations for superior blades.  Toledo, Solingen, Brescia, and Sheffield, for instance.  The Romans preferred steel from Noricum, in the province of Styria.  None of these had any special process, they just had access to good raw materials and a concentration of craftsmen who were the best at what they did.  Any time you put a bunch of specialist artists in the same place, they will strive to one-up each other.  Then they'll form guilds to keep their methods a secret from other towns, and so on.  Then the myths start spreading.  

 

 

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Thanks!

 

There's the wikipedia article, which quotes the following page incorrectly:

 

https://en.wikipedia.org/wiki/Toledo_steel

 

https://artesaniamorales.com/en/contenido/6-the-toledo-sword

 

This is why you can't trust Wikipedia! I agree it makes sense to put the wrought in the belly of the blade, it will remain soft no matter how you heat treat it. I've never heard of a clay mask quench. Will that help prevent a sword from cracking in water? As for the water, would the mineral composition make any difference? (boil slower?)

 

I'm sure there is some "magic" to it, I agree there's a lot of Japanese sword myths out there too. I didn't know that temperature doesn't actually affect a water quench. I had read that Japanese smiths tend to heat the water a bit by cooling hot iron in it a few times before quenching. At least for oil, it does seem to make for a gentler quench, (less boiling oil flying in the air!) not sure if that makes any difference on the quality of the resulting heat treat though (or the tendency to warp). I think you can expect a water quenched Japanese style blade to warp every time (at least, I've gotten my fair share of them). It's not a big deal though, you just bend it straight.

 

Urine is actually a very useful chemical. Apparently the Romans used to use it as a detergent. Let it sit in a closed pot for days until it was very ripe (lots of ammonium), then mixed with ashes on the clothes, and prodded/mixed with a wooden paddle. Apparently it actually washes clothes quite well. The main drawback is the smell!

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Wow....  :blink:  I have never seen such a pile of pure unmitigated bull manure on Wikipedia.  Absolute balderdash. Codswallop, even.  

 

Lots of smiths would laminate iron and steel, especially from the Roman period up to around 1100 AD in Europe, but they stopped around then, because technology and knowledge resulted in a better quality steel that didn't need lamination to have good properties.  

 

2 hours ago, Carlos Lara said:

I didn't know that temperature doesn't actually affect a water quench.

 

It does, but it's also highly dependent on carbon content and alloy in general.  I've cracked 1095 in iced-over water when the same steel worked fine in 70 degree F water.  If your tamahagane has a finished carbon content of 0.7% or less (not uncommon), it's not as sensitive and a colder quench does make it harder, to an extent.  Add manganese over about 0.3% and you're asking for trouble in any water quench of steels with carbon over about 0.5%.  Luckily Tamahagane has no manganese.  

 

2 hours ago, Carlos Lara said:

Urine is actually a very useful chemical.

 

It also keeps the deer and raccoons out of the garden, and confuses neighborhood dogs.  Keep a garden sprayer full of it to create an unbroken perimeter of urine around your garden or even your yard, then watch the local animals.  Only cats, rabbits, and squirrels will cross it. My former landlords in Kentucky never could figure out why the raccoons got into their garden even with an electric fence, but left mine alone.  I can just imagine the first raccoon to encounter the scent barrier thinking "Holy cow, I am not going to mess with anything that can pee an unbroken line 50 yards long!" :lol:

 

And as Geoff said, it is useful in some dye processes and leather tanning as well.  Can't make indigo blue without it (or a substitute acid), and forget true Morocco leather without both urine and dog poo... 

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I did a bit of a research paper on the effect of cleanliness of water for quenching steel parts some time ago (2013).  These were industrial parts, and my sample blocks with imbedded thermocouples were approximately 2"x2"x10" and 4"x4"x10".  Samples were low alloy steel, quenched from 1650F in 70F (+/-5) water.  The data showed that cleaner water cooled significantly faster than dirty water.  Dropping to 1000F about 5 seconds earlier on the surface and about 15 seconds sooner internally.  The theory was that fewer nucleation sites for boiling meant more water contact with the parts before vaporizing and creating a vapor jacket.  We ended up buying a big filter unit to filter down to 50 micron.  

 

We definitely controlled water temp, because that absolutely plays a role.  It could mean the difference of making properties or not, as well as cracking or not.  But again, these were much heavier sections than blades.  

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On 12/16/2023 at 9:40 PM, Alan Longmire said:

It also keeps the deer and raccoons out of the garden, and confuses neighborhood dogs.


Yup - extremely important - if I didn't use it to carefully mark out my territory around my hut the deer would destroy every young tree in no time.

Can get the chemistry to go two ways - if it's sealed away from air anaerobic bacteria will turn it into ammonia and other stinky metabolites - if you keep a gentle flow of air bubbling through it aerobic bacteria will oxidize it and you end up going towards nitrites and nitrates instead.

Either way, if a watering can full of the stuff gets frozen solid it's a pain. Also a pain if you trip over a bucket full of the stuff on your way out the door like I did...

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