The blade of this waki wasn't damaged in any way really, a couple of scuffs but that was it, however the typical frosted proprietary etched hamon was completely gone and it was my job to try and bring out the natural one that was there. I decided that being as it was a hanwei and I have had some experience with the steels they use, I would go with Lemon juice.
To anyone who hasn't done balde etching before, this no doubt sounds very basic, slightly unnerving and utter nonsense... but bear with me, my story gets better.. ;)
Because this entry is going to be little more than a small collection of pictures, I will take the time to explain the basics to anyone reading that doesn't know what this procedure is.
A differentially hardened blade has been heat treated in such a way that one part of the blade is significantly softer than the cutting edge. In the case of this wakizashi, the edge is very hard and more brittle and the spine is softer but more ductile and forgiving of percussive encounters.
The part of the blade that connects these two parts together is called the hamon, although it is generally accepted that the hamon can also mean the area from right at the edge to the first softened part on the spine. It's up to you really.Different metals form different cystalline structures but they are different. if you look very carefully at the steel on an unprepared blade, one that has been polished to a mirror finish for example, you can see the hamon but it will usually be very faint.
This pattern was so sought after, that even to this day, a good polisher (togishi) would be paid handsomely for their work. Their job is to use different stones and chemicals to bring out that patterning both in the skin of the steel and also the differential heat treatment.
I, am not a trained togishi, however, on production blades it is usually easy, if not laborious, to bring out the pattern of the hamon. For some metals, vinegar is used, others lemon juice, others yet, ferric chloride.Whatever etchant you decide to use, it is usually watered down, applied hot and onto a warmed blade for the best effect. Because of the different structures of the steel as well as different hardnesses, the etchant affects them differently and gives us this exaggerated defining line.
To the right, you can see how the lemon juice can affect the colouration of the blade. to begin with, this blade was shiny and uniform unless you looked very closely and caught the light off of it correctly.
The etchant is applied, then neutralised with a base. baking soda for example. Then the pattern is lightly polished back so it becomes less visible but far more even. This process is repeated until everything is as defined as you want with no excess oxides. the picture on the right is heavily oxidised but once it has been etched and repolished a few times, each layer building on the one before it, you will end up with something more akin to the photos below.
A nice subtle but clearly defined hamon.
When you polish back, make sure you dont leave anything unfinished on that layer or subsequent imperfections will only be exaggerated. Of course, nothing is going to ever be perfect, but look carefully and if you appear to be compounding a problem, gently polish back past it and then continue. also, dont polish only part of the sword. you will have to polish the entire blade back and then continue. Anything else will end in patches. It's worth the extra time to do and ends up with you crying less. trust me.
And that, in a nutshell is a polished wakizashi blade. I would of included more pictures but to be fair, there are only so many photos of a blade in varying states of polish that you can post before it gets insanely boring. I hope though that something in my barbles might be of use to you.
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