Hamon procedure

Agreed. I think it may be slower than vinegar or a Ferric Chloride solution but that is not always a bad thing.
I thought that the coffee etch was more of an enhancement for the color in a Damascus blade. Used after initial etch of ferric chloride. I could be wrong, still early here, the day has alot of room for me to still make errors !
 
I thought that the coffee etch was more of an enhancement for the color in a Damascus blade. Used after initial etch of ferric chloride. I could be wrong, still early here, the day has alot of room for me to still make errors !
It is used in that way but Coffee is acidic so it should be capable of etching. There again it may be slow but it should work. I have never heard of using it for a hamon but there is always a first time. I will give it a go in my next one and report my results.
 
I thought that the coffee etch was more of an enhancement for the color in a Damascus blade. Used after initial etch of ferric chloride. I could be wrong, still early here, the day has alot of room for me to still make errors !
My plan is to use it after the initial etching process with ferric. Then soak the blade and hope it affects the hamon line.
 
So...after reading this thread I was compelled to do some googling.

It appears that motor oil, due to byproducts of the combustion process, turns acidic if not countered by specific additives. Ergo, used motor oil may be mildly to moderately acidic, dependent upon the condition and/or depletion of the original additives. There is no easy way to measure the acidity of non-aqueous liquids.

Your average cup of joe is acidic at ph levels of around 4.5-6.0. I suspect that the super concentrated instant stuff that knifemakers are so fond of might be roughly double that, in line with standard household vinegar 5% at 2.4.

I was listening to a podcast here awhile back, and I believe it was Mareko Maumasi that mentioned he guessed his ferric was somewhere around 15:1 dilution, which he preferred for coloration.
 
Last edited:
I was listening to a podcast here awhile back, and I believe it was Mareko Maumasi that mentioned he guessed his ferric was somewhere around 15:1 dilution, which he preferred for coloration.
For conversational purposes, this is an interesting topic. Any acidic solution has the potential to etch or as I like to say, develop a hamon or quench line to the super picky. So my point is this, there is a reason most knife makers use a ferric chloride solution to etch their blades. In honesty, muriatic acid is easier to obtain, heck Tractor Supply carries that. So how and why did the majority decide to use ferric? I see two scenarios, 1). Some old redneck said “acid is acid” and he/she used what they had and bam great results. Serendipity. 2). A knife maker was experimenting and decided to give it a try and bam, great results. Experimentation. So who is to say that coffee, tea, or Coca Cola for that matter, will not produce something you like. Give it a try and let us know. I have learned, through experimenting, I like to develop my hamon slowly only etching for 30-45 seconds at a time then I polish with the cotton wadding (thanks Mr.Kimmi) clean then etch again until I like it. I have much more success getting that thin dark line to stand out that way.
 
Last edited:
I'd think ya have to dilute the muriatic acid compared to ferric or reduce the amount of time in contact. I've spilled muriatic from a pool supply store and was shocked at how fast it ate concrete. I haven't found ferric acid to be as violent ... might be due to the concentrations though...I don't know. The hamon effect is there weather or not you can see a defined line - so it comes to esthetics...am I right on that?
 
Why is that?
You will find most of my answers are simplistic in nature. In my opinion it does not add any performance to a knife that a properly tempered blade cannot beat. Yes, the spine will be "soft" but that means your knife will bend and stay bent (generally speaking) a properly tempered blade can flex (within reason) and will return to true. In my opinion that is a "stronger" blade.
 
You will find most of my answers are simplistic in nature. In my opinion it does not add any performance to a knife that a properly tempered blade cannot beat. Yes, the spine will be "soft" but that means your knife will bend and stay bent (generally speaking) a properly tempered blade can flex (within reason) and will return to true. In my opinion that is a "stronger" blade.

Well you can say it is just your opinion Chris, but the physics that govern the properties of the steel hold the exact same opinion, so you are in pretty good company. If one defines the "strength" of a material its resistance to deformation, ductility is virtually the opposite property. Avoiding the hardening of around 2/3 of the blade is replacing all that strength with ductility. Materials with much lower impact toughness, like very simple iron-carbon alloys (bloomery material, tamahagane, etc...) may avoid breaking with such a treatment, but would also bend rather easily. Modern alloys have a much higher toughness and are only robbed of overall strength by partial hardening.

Also, for what it is worth, not all acids are the same. I have an entire cabinet full of different acids, and other reagents, that need to be used to bring out any number of different microstructures in steel for metallography. Straight HCL or muriatic, is not the same as FeCl. FeCl is HCL that has been supersaturated with an iron solution, that is why you need to dilute it to get it to cut, it cannot hold any more iron at full strength. This chemistry causes FeCl to not only remove material but also deposit a dark oxide on the surface of the attacked metal. HCL, or muriatic, is more aggressive and so it only dissolves the metal while leaving it a dull gray on grey; it also will pit if not carefully monitored. But one can use HCL to get a topography and then color with other etchants, it is just easier to do both with FeCl. I personally despise the look of an FeCl etched hamon, and prefer to use other acids that will turn it bright and glowing with highlighted activity, to show off the actual heat treating effects, rather than just make a mottled grey blade.
 
Well you can say it is just your opinion Chris, but the physics that govern the properties of the steel hold the exact same opinion, so you are in pretty good company. If one defines the "strength" of a material its resistance to deformation, ductility is virtually the opposite property. Avoiding the hardening of around 2/3 of the blade is replacing all that strength with ductility. Materials with much lower impact toughness, like very simple iron-carbon alloys (bloomery material, tamahagane, etc...) may avoid breaking with such a treatment, but would also bend rather easily. Modern alloys have a much higher toughness and are only robbed of overall strength by partial hardening.

Also, for what it is worth, not all acids are the same. I have an entire cabinet full of different acids, and other reagents, that need to be used to bring out any number of different microstructures in steel for metallography. Straight HCL or muriatic, is not the same as FeCl. FeCl is HCL that has been supersaturated with an iron solution, that is why you need to dilute it to get it to cut, it cannot hold any more iron at full strength. This chemistry causes FeCl to not only remove material but also deposit a dark oxide on the surface of the attacked metal. HCL, or muriatic, is more aggressive and so it only dissolves the metal while leaving it a dull gray on grey; it also will pit if not carefully monitored. But one can use HCL to get a topography and then color with other etchants, it is just easier to do both with FeCl. I personally despise the look of an FeCl etched hamon, and prefer to use other acids that will turn it bright and glowing with highlighted activity, to show off the actual heat treating effects, rather than just make a mottled grey blade.
Thanks for that Kevin, that makes sense. If you do not mind sharing it (its OK if you do I will not be offended) what is your preference for developing the hamon. I have only tried diluted FeCL and diluted white vinegar. I am always willing to experiment with different techniques. By the way, I saw you on Nation Geographic (Ultimate Viking Sword) that was one awesome process you guys used to create that sword. I really enjoyed the documentary.
 
Back
Top