(Please forgive my grammar as I never managed tolearn the proper way to use punctuation and need to read up on it. Grammarly can only do so much.)
First I feel I should give a little history lessonas not every person on the planet has studied the history of Asia and well Istill have a lot to learn I have done a bit of studying on the history of theeast thanks to the great courses lecture series. The technique of applying clayto the spine of a blade did not, in fact, originate in japan it originated inChina and then spread threw out the east, however, the Japanese did perfect theartistic aspect of the Hamon. It was used from the middle east (source, a Studyof Easter Sword by Kirill Rivkin and Brian Isaac which I am still working through.)
The biggest advantage of claying a blade is itgives you a hard edge with a soft spine and well it does not need tempering ifyou temper a blade the edge will be less likely to chip, the hamon is just a byproduct of this technique and does not show in steels that have too muchmanganese or chromium and these elements do occur in raw iron ores.
Now the current ABS introductory text Introductioninvolves the Edge quench which I personally have a big issue with as it requiresthe use of an Oxy-acetylene torch. I am a trained welder and have completed 3-6-monthcollage course for welding. I learned how to use an Oxy-acetylene torch and it’sreally the most dangerous torch out there because even if it assembled and maintainedproperly their careless use can cause the head assembly to explode. So, on the dangerscale, it comes in silver the buffer taking the gold.
Also, there are also risks with blue backing as forgedin fire has shown that a moment's carelessness can cause you to completely removethe temper or even cause the blade to crack. I have never done an edge quench asI just did not have the funds to get an Oxy-acetylene torch and honestly, it seemsto take longer to perform right. With clay, all you need to do to achievea hard edge and soft spine is put the appropriate amount of clay on the sides, spine,and front of the riccoso to slow the cooling rate of these areas of the blade.
Well, clay quenching does have some drawbacks butso does blue backing and edge quenching and just quenching in general. However, I feel that clay quenching is reallythe safest way to get a soft spine and a hard edge as you just need some Rutlandblack which cost around 13$ last time I checked, well a new Oxy-acetylene torchset cost 109+$ for a cheap one. Then you must buy or rent the tanks forit and I am not sure how much that will set you back. So, in the end, it wouldbe a good idea to add this to the ITB book as it is just a great way to get ahard edge with a soft spine. it’s my opinion but you should still temper yourblade after the quench to prevent the edge from easily chipping. However, as I amjust a lowly apprentice with no real reputation so I do not know if my wordshave any merit, so I hope the masters can enlighten me on if this should be inthe included in the Introduction to bladesmithing book.
Side Note: about Page 12-13 also well the designs forthe straiting tool and shoulder filing jig are great, they require the smith tohave a welder and that is generally not something a beginner would be able toafford despite them being cheap. Well, I have not gotten around to it yet triedit out, yet I believe all these great tools could be made by riveting themtogether instead of welding them. Cause I believe they would have had toolslike these before the 1900s when the arch welder was commercially available.
I hope you guys do not mind this as they are my observations,I made well preparing to make a blade for the JMS shop test. I need to state that I only have my ownobservations to go on and I have a reputation for arguing over on facebook so Ihave very little credibility in the bladesmithing community right now, so itwould be nice if someone would be kind enough to repeat my tests. :
Firstreally to do a clay quench right you need to leave the bade in your quench mediuma lot longer than its nickel ball rating I only really use parks 50 which is a7-9 second quench however depending on the blade it takes around 25-30seconds for the steel to fully cool. However, you do not need to time ityou just need to wait for your medium to stop boiling. I also feel that the fact that the heat of theblade causes your quench medium to boil it prevents the edge from softening fromthe heat radiating back into the spine, however, I do not own any form ofhardness checker other than a Nicolson file so I can’t say how it softthe spine would be if you let your steel fully cool in your quench medium.
Finally, this is just a bit of a crackpot theoryof mine but with the right amount of clay, you could have the spinebecome bainite. However, I cannot do any experimentationto see if it's possible until I can get the right equipment needed to check for bainite.
Hello Kevin, your post reads as if you are somewhat passionate about the topic. I would say that you need to take the Intro Course with the right instructor as I can be passionate as well. I despise edge quenching, a little part of me died every time I had to teach it, and I have sound metallurgical reasons for these reservations. So, at the August Intro to Bladesmithing, that I taught at the SOFA school, I showed my students the clay coating technique and had a much better success rate in the tests. The only hesitation that I had was in teaching a method that has become so cliché on contemporary handmade knives that I had guilt in contributing to a rather hackneyed fad.
Edge quenching is indeed a safety concern as I have yet to teach a class where at least one student doesn’t flash the oil from the unquenched hot steel. And even when I did teach it, I used a forge and fire brick to isolate the edge heating as I will NEVER teach, or endorse, the use of a torch for austenization, as an educator I should do better than that.
I have all of my students do two test blades- one clayed, or differentially hardened, and one fully hardened and differentially tempered, so that they can see the marked difference in elasticity and strength. Because, after all, the clay method is just another compromise as well, to accomplish the bend test. It sacrifices strength for ductility and is best used for aesthetic reasons on anything but test blades. Indeed, when coupled with proper spheroidal annealing, a test blade will bend as easy as an old katana when getting out of alignment in a heavy cut. But at least the hardened edge is much more homogenously martensitic and sound.
"One test is worth 1000 'expert' opinions" Riehle Testing Machines Co.
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Hello Kevin, your post reads as if you are somewhat passionate about the topic. I would say that you need to take the Intro Course with the right instructor as I can be passionate as well. I despise edge quenching, a little part of me died every time I had to teach it, and I have sound metallurgical reasons for these reservations. So, at the August Intro to Bladesmithing, that I taught at the SOFA school, I showed my students the clay coating technique and had a much better success rate in the tests. The only hesitation that I had was in teaching a method that has become so cliché on contemporary handmade knives that I had guilt in contributing to a rather hackneyed fad.
Edge quenching is indeed a safety concern as I have yet to teach a class where at least one student doesn’t flash the oil from the unquenched hot steel. And even when I did teach it, I used a forge and fire brick to isolate the edge heating as I will NEVER teach, or endorse, the use of a torch for austenization, as an educator I should do better than that.
I have all of my students do two test blades- one clayed, or differentially hardened, and one fully hardened and differentially tempered, so that they can see the marked difference in elasticity and strength. Because, after all, the clay method is just another compromise as well, to accomplish the bend test. It sacrifices strength for ductility and is best used for aesthetic reasons on anything but test blades. Indeed, when coupled with proper spheroidal annealing, a test blade will bend as easy as an old katana when getting out of alignment in a heavy cut. But at least the hardened edge is much more homogenously martensitic and sound.
I am glad I am not the only one who thinks edge quench is not something that should be taught to beginners. I would love to talk more about metallurgy with you after I have finished reading Doctor Verhoeven's metallurgy for bladesmiths and others who heat treat steel and forge steel. well I find metallurgy fascinating the book is still a long somewhat dry read and I took a break from reading it in the middle of the stainless steel section.
I plan on eventually taking the class but right now i do not have the funds as right now all the schools are 4 or more states away and right now that is just too far for me to travel. so I can't take it till after I pass the shop test and can start selling, as I had made a vow not to start selling until I have that piece of paper. For now, I am hopefully starting an introduction to blacksmithing class held by the guild of metalsmiths which should help me with knowing where I stand when it comes to forging things. it depends on how many slots are still open and if they're filled before my check reaches them. I hope you do not mind but I am going to share a link to this post on my facebook page because I have been arguing on facebook of which of the two techniques is easier for a beginner. I prefer to only share things personally i know works and I am both self taught and I never namedrop...which may be why I have a reputation for being arrogant over on facebook.
aslo, I need to say Thank You as about 3 years ago when i started looking up how to make blades in your site http://www.cashenblades.com/heattreatment.html was were I first learned some more in-depth metallurgical knowledge.
