SOTW #16 - Differential Hardening Sunnobi Tanto - yakiire with water, charcoal, clay

[@chrissmith4568]

Magnificent video! I love watching the pro's work, I not only learn but am also inspired. Thank you for doing what you do. No obnoxious music and talking, just directly to the point/technique by showing it clearly.

[@AlexCanciois-an-awesome-guy]

As always, a great video and very informative

[@draven3838]

Absolutely amazing work ,I'm a fairly new subscriber so I'm going way back on your videos and watching them all .awesome channel thanks again

[@islandblacksmith]

Yakiire - Differential hardening a classical style sunnobi tanto blade forged from century-old reclaimed shear steel. Sunnobi tanto are larger than ordinary tanto (nagasa above 1shaku) and may have sori similar to ko-wakizashi. see the whole process of forging this tanto here: islandblacksmith.ca/2018/03/utsushi-study-of-a-sunnobi-tanto/ 1. Using approximately a 1:1:1 mixture of natural clay, polishing stone powder and ground charcoal to mask the back of a hand forged blade about 1-1.5mm thick to slow down the cooling rate. 2. Brushing on a thin slip layer with extra charcoal added along the exposed edge to speed up the cooling rate and protect from carbon loss. 3. Carefully heating in a charcoal forge supplied by air from a fuigo box bellows until the edge reaches critical temperature. 4. Plunging edge-first into cold rainwater to cool the blade quickly and harden the edge while leaving the rest tough and resilient. 5. Testing for successful hardening with a file and then removing the clay with a mild steel scraper. 6. Slightly reheating the blade over the flames to temper the edge. 7. Test polishing on a coarse Japanese waterstone to check the hamon. more about the process: islandblacksmith.ca/process/ more about yaki-ire: islandblacksmith.ca/process/yaki-ire-clay-tempering/

[@Jacob-db4pn]

Do you have any tips for successful quenching in water? I've heard that you ought to use brine because it reduces surface tension and helps break up the vapor jacket, but also heard that it makes it a more aggressive quench medium. I've had some success with it in the past (4 out of 5 blades survived with no cracking), but the last one broke and made me skeptical of my own methods and I thought I would ask you for some pointers. Love your channel and your work, you inspired me to forge a tanto with a soft core and high carbon jacket and now I'm afraid to quench it, haha.

[@xjestr89]

Another great video Dave, keep it up!

[@e.d.7742]

Another amazing video! I always love seeing your work. You inspired me to start working on a tanto (using stock removal via hand tools only) I'm just currently at a standstill because I don't have a hot enough heat source for Yaki-ire. My blowtorch doesn't quite cut it. I think I'll make an air-fed charcoal fire and do it the old fashioned way☺️

[@islandblacksmith]

the journey toward excellence is long but worth traveling! i recommend working with kata for pattern study: islandblacksmith.ca/2014/04/aizu-shintogo-kunimitsu-tanto-kata/ (or get a whole set of precision cut ones from pierre: soulsmithing.com/product-category/kata/ )...yes, charcoal with a pipe in one side near the bottom is pretty simple, doesn't take much air either...

[@blcouch]

E. Doss lump charcoal and a hair dryer with the heating element disconnected will get you plenty hot. A capped iron pipe with holes in it with dirt or old bricks lining both sides makes a decent heat treating forge to start with.

[@banzzz6337]

you are amazing at what you do i hope i can be as wise and knowledgeable as you are some day. Thank you for this information i will put it top great use. 😀

[@islandblacksmith]

there is more about the whole process of forging this tanto here: islandblacksmith.ca/2018/03/utsushi-study-of-a-sunnobi-tanto/

[@pefdu62]

Hello, What's the difference between a sunnobi tanto and a ko- wakizashi with a hira sukuri shape ? Thanks for all your videos

[@islandblacksmith]

mainly the time period and the law governing swords at any given time ^___^ ...depends who you ask but if you want to try and split hairs sunnobi tanto may tend more towards a tanto kata and only be slightly above 1shaku whereas kowakizashi may have more sori and exceed 1shaku 1sun length (for my own purposes i might put the cut off at ~12sun/36cm/14")...both kowakizashi and sunnobi are special case designations on the edges of their categories so it is expected that there will be some overlapping area...all i know for sure is that this exact kata was designated sunnobi by the smith who forged the original...

[@msblades5382]

Crossed heart forge. Let me start by thanking you for you taking your time to give us a glimpse into your process. As a very new BladeSmith I a, having an extremely difficult time getting the product or recipes for a proper clay. I see your recipe and have the as you mention natural clay is this store bought like a satinite and as far as polishing stone powder is this also something that would need to be bought as well? I honestly have no resources to acquire these products. I hope you can give me some guidance and perhaps a way to acquire said product. I am currently using Rutlands furnace cement and hate it. It swells when HT and either falls off before or during the quench. I have since started using a stainless steel jewelry wire to hold the junk on. Please help...... Martin

[@islandblacksmith]

it is a challenging process for many reasons, keep at it! have you studied the article on yakiire: islandblacksmith.ca/process/yaki-ire-clay-tempering/ there are clues on the function of each of the three main ingredients and adding more of one will increase the corresponding property of the mixture...natural clay out of the ground or scraps from a potter...ground up charcoal...and polishing stone powder is saved from rough stone polishing work, or finely ground sand can serve a similar purpose...start with 1:1:1 and the rest is a lifetime of experimenting...

[@stevesyncox9893]

Thanks Dave.

[@aymanboughanem881]

I know the video is relatively old but here goes... Im using reclaimed modern steel ( truck leaf spring) im kind of afraid of water quenching but i heard in some parts of rural britian,muddy water is used as a substitute to oil by traditional blacksmiths. So my question is, if im using modern steel that has the tendency to crack when water quenched, would having some clay in the water itself help reduce the risk? Edit: in case i wasnt clear enough, im attempting to use the yaki-ire method but i am thinking about using muddy water to minimize cracking risk (i must be missing some major concept and would he grateful if you could explain it)

[@islandblacksmith]

never heard of it but it could be worth testing, let me know what your research reveals...water that is very hot, just off the boil, behaves differently than cold because the vapour jacket forms so quickly and lasts so long...

[@aymanboughanem881]

@@islandblacksmith ok great, thank you for the amazing content, the quick replies and for the encouragement

[@roninviking2373]

I have always heard that 5160 is not a good steel to differentially harden because it cracks easily in quench. I notice you work with it a lot via leaf springs, is this a problem you have had? I'm asking because I like working with reclaimed steel as well.

[@islandblacksmith]

i have heard the same of 5160, but i don't know much about numbered steels, my 100+ year old leaf springs are simple carbon alloys...the simplest available reclaimed modern steel is old files, great for yakiire...

[@jamesgroomes1812]

Spring steel 5160 is an oil quench steel.

[@islandblacksmith]

i have quenched modern leaf springs in water many years ago but it is a challenge for sure!

[@aleistervillaseca438]

Great job man, make a wakizashi :D

[@islandblacksmith]

maybe one of these days....this would be considered wakizashi during certain eras and by certain standards....sunnobi tanto is the length of a short wakizashi and may have the sori of ko-wakizashi but with the overall shape and design of a large tanto...

[@eugenetan7323]

Hello a quick question I notice that you have little to no power tool when forging so may I ask for advice in adding the bevels and the edge on a blade ? and also will very rough grit sandpaper going to fine grit be enough ? thank you

[@islandblacksmith]

bevels are mostly forged, a file cleans them up before yakiire, and afterwards coarse waterstones to finish the shape...no power tools necessary, but that last step takes a lot of time by hand...

[@eugenetan7323]

Crossed Heart Forge - islandblacksmith thank you for your response ^^ i'll keep those in mind

[@tylerharvey8671]

As usual, amazing work. It's your work that inspired me to make my first habaki. Have you ever thought about making a naginata?

[@islandblacksmith]

i suppose it is on the list somewhere, but there are a few major steps in terms of progression between here and there before i am ready to tackle that geometry...

[@londiniumarmoury7037]

So I've been doing it wrong then, because I haven't been putting a thin strip over the edge. They were hardening and creating a hamon though. It makes sense to keep the carbon in. I'm going to give this a shot.

[@islandblacksmith]

do it if you can but it generally works fine without, the slip layer can speed up the edge cooling which is not always good for modern steels, and the carbon retention is always good but depending how much extra steel you leave at the edge, how much carbon you can spare, and how long you leave it at temperature the effects can be minimal...

[@londiniumarmoury7037]

@@islandblacksmith Hmm, so it depends on the steel type, I guess you do it because you use old steel that you salvage. I think I will do it the way you do when it comes to using older steel, and doing it without the thin layer with modern steel. Thanks again.

[@islandblacksmith]

i can't find your last comment, youtube glitch...something about steel testing...this is all i can read from the notifications list, "So you actually test the steel on camera, first time don't you, without a test run off cam. when you broke that chunk of steel off, it was in it's martensite quenched state, and you were testing th..." ...i wasn't testing in that video as i already knew this was good steel, the first cut was to remove everything that was too thin to upset without buckling/cold shut...the second cut later is the way you always form the tip so that the grain flows around with the edge...steel testing info here: islandblacksmith.ca/2016/12/testing-reclaimed-steel-for-knife-making/

[@londiniumarmoury7037]

@@islandblacksmith Yeah I was asking about if you test the steel before you make the video, or if you make sure it's high carbon with the test you use beforehand. I only ask because I recorded a Video of an entire forge build, and I didn't test it first, ended up being mild steel and I chucked it, along with the video. Thanks for the link, I have your web page bookmarked and I wrote down a lot of your tutorials so I can bring them around with me and read.

[@islandblacksmith]

yep, good plan to test everything before putting a lot of time and energy into a project...video or not makes no difference... ^__^

[@giraybagci8660]

Do you just use normal clay to mask the back of the blade or does it have some sort of recipe too?

[@islandblacksmith]

there is a basic recipe but it usually needs fine tuning for different cases...check the link and info in the description...

[@clydeulmer4484]

Love the contemplative nature of your videos. I've only made a few Japanese-styled blades (styled, because I work with modern methods, tools and steels) and had decent success with plain old Rutlands. I generally forge with W2 and 1095 and try for hamons on almost anything. I have some desire to try the traditional recipes, though, which lead me to my question: Is the 1:1:1 ratio by weight? I'm presuming so, but... Being a math/science geek, I'll probably start with kaolin potter's clay, colloidal or powdered silica, powdered charcoal of known mesh size, and maybe some powdered iron. Too many years of lab work to do otherwise :-) Clyde

[@islandblacksmith]

i do like the simplicity of the natural materials...i believe it is best by volume, you will have a lot of charcoal if by weight...there is a link in the description to an article on yaki-ire that talks about which property each of the three main ingredients effects so you can adjust your mixture to correct issues...enjoy the journey!

[@clydeulmer4484]

Doh... If I'd spent 5 seconds to consider the relative densities... That could have gone terribly wrong :-) Many thanks. Clyde

[@islandblacksmith]

...though by weight you might get a good mixture for the slip on the exposed part of the edge...see how it goes!

[@vgullotta]

Another great video, man I bet your blades are amazing in person! Is that just water you are brushing on the blade in the beginning to make sure it's nice and clean around the clay?

[@islandblacksmith]

it is a very thin slip layer of the same mixture with extra charcoal powder added...it actually cools faster than bare steel if thin enough...and it also protects the edge from oxidization which decreases carbon content...

[@allymariachi9230]

do you ever perform normalizing cycles before hardening? if so,doesn't it affect the carbon content

[@islandblacksmith]

yes, usually at least one proper cycle at the end of forging to get rid of hard spots from the water forging, but normalizing is also worked into the forging process itself by way of technique and careful heat control, the grain before forging one of these century-old springs is quite coarse but after a few heats tightens up nicely...normalizing is about grain size rather than carbon content, the main factor there is what you start with and how long it sits in an oxidizing environment (a charcoal forge is either carburizing or fairly neutral)

[@allymariachi9230]

+Crossed Heart Forge - islandblacksmith I was wondering.can you substitute the natural clay with normal masonry cement?.the building type cement

[@islandblacksmith]

i have no idea, but my guess is no...it is a very different material...clay from the ground is fine, just put it through a fine screen to get the rocks out...or get trimming scraps from a potter, they usually have bags of it...

[@allymariachi9230]

+Crossed Heart Forge - islandblacksmith thank youso much for replies.you have been helping me soo much.am actually experimenting on it as am writing this

[@RovingPunster]

I have no first hand smithing experience (rotator cuff), but i watch a lot of vids, and the pattern you used at 0:25 seemed a bit conservative. Most traditional vids ive seen go for a more interesting hamon by using wavy rather than straight lines, and even brushing crosswise in places to create a 'cloud' effect. I'll look thru your library for other vids on hamon technique ... meanwhile, it's great to see a love for traditional historical techniques and artistry. I would be the same if I were able to smith. Respect.

[@islandblacksmith]

suguha is the *most* traditional pattern there is, the original and still classic after more than 1000 years...it is the style i work in, everything else seems too flashy and modern to me ^____^

[@RovingPunster]

@@islandblacksmith Aaah, thank you. I learned a new term today. I didnt know there was a whole library of pattern names for hamon just like there is a long list of different point geometries for japanese swords. Thanks again. I really wish there was a local bladesmith around here doing traditional methods that I could visit, but the few that exist in my area are all machinists, not smiths. I find the forging so much more interesting than simply grinding.

[@islandblacksmith]

i have more than a few lifetimes worth of stuff to learn yet too...good old school machinists are a dying breed in many places too!

[@RovingPunster]

@@islandblacksmith Just to clarify, I meant to say that my interests in this niche gravitate far more strongly to hand forged blades, rather than ones simply machined from precut mass produced stock metal. I didnt intend to disparage machinists or machining in general. Cheers.

[@islandblacksmith]

ah, got it...i read too quickly and thought metal workers in general rather than knifemakers...yes, forging is fun and challenging!

[@bmxriderforlife1234]

Haha with Japanese swords sizing them and classifying them can be unusual. I have an old wakizashi that's technically a katana blade due to length but it's been mounted as a wakizashi for a loong ass time. You can find similar things with tanto and wakizashi.

[@islandblacksmith]

indeed!

[@stanchotoshev1173]

how do you make a clay?

[@islandblacksmith]

islandblacksmith.ca/process/yaki-ire-clay-tempering/

[@junjampingnolimit5377]

The best boss 👍🗡️

[@gavin3488]

So how was the snow last week?

[@islandblacksmith]

plenty of snowskating to be had, even fresh light powder for a couple days!

[@gavin3488]

yeah the weather has been funky for the past little while. We had snow down in Victoria, which cause some fun. On the side note, I very much enjoy your video on the black smiting process as you use a traditional manual tools and such. also because don't consistently yell into a mic, and use "Damascus steel" consistently to make "silly objects" ( I use "" here because some people like it). Instead you make pieces of natural beauty (in my opinion). Thanks for the uploads!

[@islandblacksmith]

we each gotta do what we gotta do, carry on!

[@aymanboughanem881]

@@gavin3488 u sure like alec dnt you ;)

[@MultiBegbeg]

magnifique !!!

[@ians1464]

Nice

[@berdohan1]

the light is insufficient in video shooting.!

[@islandblacksmith]

good steel is more important than good video ^___^

[@меруертшобалаева]

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