TLDW #26 - Traditional Yaki-Ire, Hardening a Tanto
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- Опубликовано: 5 янв 2020
- **WARNING: This is the longer process version intended for serious students of the forge.
Traditional clay/charcoal/water yaki-ire, differential hardening a classical tanto style kotanto blade forged from reclaimed carbon steel. more on yaki-ire...
Process of Clay Tempering a Tanto Blade
islandblacksmith.ca/process/ya...
Once the steel is shaped as much as possible in its softer state, it is coated with a thin layer of clay along the edge and a thicker layer on the body and spine. During the hardening process, the split second difference in cooling time caused by the clay layer creates two different hardness areas in the same piece of steel. The edge cools faster and forms a very hard steel structure called martensite while the body cools slower and forms a very tough steel structure made of ferrite and pearlite. The boundary between these two areas is called hamon and is commonly seen as a frosted wavy line down the length of a polished sword blade.
The clay is a mixture of approximately thirds of natural clay, crushed charcoal, and polishing stone powder. Each smith has their own recipe but the basics are the same...natural clay: to make it stick, polishing stone powder: to keep it from shrinking and cracking when it dries, and charcoal powder: to keep it from cracking when it is heated...knowing these properties allows a smith to make adjustments as needed.
The spine and body of the blade are coated with a thin layer of the clay mixture to insulate and slow down the cooling while the edge and tip are coated in a very thin slip layer which actually cools faster than bare steel and protects from oxidation while heating.
When the clay is fully dry, a charcoal fire is used to heat the steel slowly and evenly, taking care not to overheat any part of it and working in the dark for accurate colour viewing. First the spine is heated to bring the whole blade to just below temperature, and then it is flipped over to focus heat on the edge. When the entire edge is at the correct temperature, it is plunged into a hot water bath, edge down, and held until cool (yaki-ire). The tang is not heated or hardened and can be drilled later for the mekugi-ana. The hardness is checked with a file and the process repeated if necessary. After hardening, the clay is removed and the steel is heated slightly again to remove some of the internal stresses (yaki-modoshi). Once this process is finished, and if the steel survives, the blade is ready for Togi, shaping and hand polishing using waterstones.
islandblacksmith.ca/process/
**WARNING: This is the longer process version intended for serious students of the forge.
Traditional clay/charcoal/water yaki-ire, differential hardening a classical tanto style kotanto blade forged from reclaimed carbon steel. more on yaki-ire...
Process of Clay Tempering a Tanto Blade
islandblacksmith.ca/process/yaki-ire-clay-tempering/
Once the steel is shaped as much as possible in its softer state, it is coated with a thin layer of clay along the edge and a thicker layer on the body and spine. During the hardening process, the split second difference in cooling time caused by the clay layer creates two different hardness areas in the same piece of steel. The edge cools faster and forms a very hard steel structure called martensite while the body cools slower and forms a very tough steel structure made of ferrite and pearlite. The boundary between these two areas is called hamon and is commonly seen as a frosted wavy line down the length of a polished sword blade.
The clay is a mixture of approximately thirds of natural clay, crushed charcoal, and polishing stone powder. Each smith has their own recipe but the basics are the same...natural clay: to make it stick, polishing stone powder: to keep it from shrinking and cracking when it dries, and charcoal powder: to keep it from cracking when it is heated...knowing these properties allows a smith to make adjustments as needed.
The spine and body of the blade are coated with a thin layer of the clay mixture to insulate and slow down the cooling while the edge and tip are coated in a very thin slip layer which actually cools faster than bare steel and protects from oxidation while heating.
When the clay is fully dry, a charcoal fire is used to heat the steel slowly and evenly, taking care not to overheat any part of it and working in the dark for accurate colour viewing. First the spine is heated to bring the whole blade to just below temperature, and then it is flipped over to focus heat on the edge. When the entire edge is at the correct temperature, it is plunged into a hot water bath, edge down, and held until cool (yaki-ire). The tang is not heated or hardened and can be drilled later for the mekugi-ana. The hardness is checked with a file and the process repeated if necessary. After hardening, the clay is removed and the steel is heated slightly again to remove some of the internal stresses (yaki-modoshi). Once this process is finished, and if the steel survives, the blade is ready for Togi, shaping and hand polishing using waterstones.
islandblacksmith.ca/process/
Thank you so much for all your masterful advice. I from a very young age have always had love for Japanese steel. And thanks to you i've learned so much that word's cannot demonstrate my immense gratitude to you God bless you.
i am glad that my journey of learning has been helpful to yours!
Can u give me a list hamon materials?
@@ROBERT_B3R7 ...top secret information only for those who seek diligently...or, read the comment you are replying to... ^__^
Glorious video, great job showing the water drop test!
this footage does illustrate the temp difference pretty well, only thing better would be a close up of the dance...next time!
As always, a show of true artisanship, almost zen like. A true inspiration for anyone in this day and age. Thanks for the video !
Well done, Dave! Much respect. Can't wait to visit this spring! Love the shop and video work. (and the llamas)
This is what I have always been waiting for!
Always come a smile on my face when i see ur notifications. Time to learn for me👍👍👍
thank you for studying!
Thank you for sharing video of the process and the details in writing
YES! I love your videos!!!!!
Nice love watching these keep up the work
Thank you
Are you going to be posting a polishing video any time soon? Love to know how you polish your blades.
polishing would not be a very interesting video, but one of these days i suppose...in the meantime this page is more detailed than a video: islandblacksmith.ca/process/togi-hand-polishing/
Crossed Heart Forge - islandblacksmith ahhh I’ll take a look. I’m currently on my first tanto and the geometry and polish are giving me trouble.
I was hoping in a few months I would attempt a Osoraku Zukuri Tanto but it might be a bit too much for me. Thanks for the link!
this is the most useful archive for geometry, especially the earlier articles that break down tang, machi, kissaki, etc: islandblacksmith.ca/tag/tanto-geometry/
Salut
première vidéo de l'année
je vous souhaite à tous une bonne et heureuse année
I'm right in the middle of taking a break from building one of those fuegio box bellows, and I went to test it and it ain't blowing shit! I think the soda bottle teflon labels as valves isn't working. Not to mention all the air leaks. Hey do you have one of those hinges in the plenum that cuts one half of the box from the other? And what happens if you don't install one?
everything you can see in this video is all there is, the plenum/manifold is just a box with two valves going in and one hole coming out: ruclips.net/video/oUMt0gTIsCw/видео.html ...there is a valve troubleshooting section at the bottom of this page: islandblacksmith.ca/2015/11/making-valves-for-fuigo-box-bellows/
Your video is a true work of art. I love the calm, non verbal atmosphere. Where are you located? I would love to be able to just sit in and really learn from your methods. Amazing work my friend! And I love your two toed “ninja” shoes!
much appreciated! on vancouver island, but there are hours and hours of video and plenty of photos and info on the website for study as well!
Question. I see many videos of yaki ire and some smith coat the edge in a thinner type of clay mixture along with the spine while others coat just the spine and shinogi. Which is better/easier to do?
both work but there are good reasons to slip coat the edge...there is a link in the description for a whole lot more info on the process which will help your research...
Do you do any forge welding with that charcoal forge? If so, I would be very interested in a video detailing the specifics of how you manage your fire before and during heating for forge welding.
once in awhile but not much lately as the charcoal supply is so limited...piled up deep and keep the air as low as possible...clean out the fine stuff around the tuyere between major heats...it is actually much cleaner than mineral coal but takes a deep fire to protect from the air blast...
Cool Dave.
thank you, steve!
if you make a knife from a file, what is better to temper, in water, or in oil? thanks!
i only know water and clay method, but files are very good for learning water quenching...
What is the w hite powder on the other can? Thanks for an answer
clay...check the description for the three ingredients, links, and much more info...
Can you please tell me the clay you are using. I got very high plasticity green fire clay and it has to much shrink even with fillers. Only thing available local. Can you point me in the right direction for good adhesive clay. Thanks.
i have used several kinds of clay, scraps from potters, even from the ground...there is a trouble shooting section at the link in the description, the basic recipe is only 1/3 clay so you need plenty of the other two ingredients before it gets near the functional zone...
👍🏼👍🏼
I have never seen a hand-whetstone produce sparks, that must be a wonderfully rough gritted stone!
if the clay pattern is not symmetrical on both sides, does it come out that way on both sides?
or does it create a hamon that is a mix of the clay pattern of both sides?
depends on how shallow hardening the steel is, the blade geometry, and how much difference...but hamon do their own thing in general...80 grit sun tiger waterstone, dry...
@@islandblacksmith mhm, hamons=still magic.
thx, I was looking for a really coarse stone for sharpening Sen (my research says Sen need a rough micro serrated edge?)
What is a slip layer made of? Do not understand
you can find a lot of info in the description and a link to the website for more...
Was that normalizing process after the quench when you've been testing the temp with drops? Very impressive work!
normalizing would be done after forging and filing, but before applying any clay, to "reset" the steel grain and remove any stresses that may cause cracks during yaki-ire...after yaki-ire (quenching) comes yaki-modoshi (tempering), which removes some of the hardness but is a very low temperature operation compared to normalizing or quenching which are done in the critical temp range at "red hot" or slightly higher...
How would I water quench without cracking? Ive heard you have to use close to boiling water to avoid thermal shock and that the steel has to reach a temperature of about 850 degrees C, to when its not magnetic anymore and has a cherry red/pink colour. But im still worried about the risk of it cracking. 😕 Also the steel for the tanto im making is a Damascus steel and i believe it is made of 15N20 and 1095 steel.
it is a very difficult technique with *many* variables and takes a long time to learn, the best steel to start with is old files, then progress to scrap pieces and small test knives with your steel, then it might take a few tanto before you start to succeed regularly...
@@islandblacksmith i dont have files, but i have a few old soft knives i can practice on. Ill try that.
better than no practice, but each steel is different so pay close attention to the variables you know of and can control...
It's funny because I'm about to harden my tanto haha just not sure if quenching it in water or oil, I'm a bit scared of broken or curving it in doing in water. Nice video
it happens to everyone, it may take several tries to succeed, and many more to master traditional water quench yaki-ire...
@@islandblacksmith Yes I guess I have to fail first, thats something I always forget
not necessarily, but there are indeed many steps between an idea and mastery, some may be failure but all should be learning...
@@islandblacksmith Thank you mister
Just a question Mr. Dave what kind of clay you've used earthen clay or stoneware clay? Thanks for answer 😃😃
i don't know what the difference is, but clay from the ground even works so the important thing is you test and adjust the mixture so it doesn't shrink or fall off anywhere in the process...
Thanks for an answer mr. Dave
Bro, why you close your door, before hardened? Very interesting)
trying to keep the lighting consistent every time, temperature is judged by colour...
Recipe clay ?
links in description..
what should be the minimum and maximum thickness of the clay on the blade... I tried with a 5mm thickness on two knives using this recipe but clay from one fell off and the other though i was able to heat treat i do not see a hamon. I etched it with ferric chloride and what I could see was dark edge and a light body. what I can see from your video is that the thickness of the clay you put is not more that a millimetre or so. Can you please help.
yes, about 1-1.5mm is good, if the edge etched dark you probably did get a hamon...there are many variables but keep working on it! more info here: islandblacksmith.ca/process/yaki-ire-clay-tempering/
@@islandblacksmith thanks for replying. could you tell me one more thing, I mix 1:1:1:1 powdered stone, powdered coal, clay, and powered pottery clay from a broken pot. All of it very finely ground. I sand it to 80 grit put on the clay heat it up, but when I quench (in water) it all falls off… how can I make it stick as after that I don’t see a darker edge but the complete blade gets hardened. Note the clay falls off during the quench not before.
falling off in the quench doesn't mean it did not work, but it usually doesn't *all* fall off...more clay will help stick, keep practicing...was it a file? other steel like modern spring steel may harden all the way through even with clay...there are many variables and no guarantee of success, keep trying!
@@islandblacksmith so kind… one was from a file another from a bearing steel I guess 52100 and one from spring steel… what would you suggest as we have none of the recommended steel here… any specific automotive part I can use to try… thanks again…
use file steel to learn, they are quite consistent and will show hamon if you get the process and details correct...keep trying!
Ламы)))