The new/old kanna has one aspect that I am not thrilled about.
|You can see how the grain of the wrought iron has been distorted.|
Just about every kanna that I've bought has had this condition to one degree or another. When you are a carpenter, you don't carry some special little frou-frou brass hammer for adjusting your plane, you use what's in your hand! That's a steel hammer, ergo.... Hammer head, the mushroomed-over top on the blade. Plastic deformation of metal sounds a bit wordy.
Compounding the choice in kanna blade adjustment devices is the material that the kanna blade is made from. The tool that I want (and sometimes actual get, haha!) is a higher quality plane, and they usually have blades made from wrought iron.
Wrought iron is a great material for kanna blades, because it is soft, so it sharpens easily. Being soft also means that performing ura-dashi (tapping out) on a blade made with wrought iron is MUCH easier, than on a blade made from regular modern soft iron. Ren-tetsu, good for kanna (but not for chisels, maybe).
Wrought iron being soft, and easily deformed, causes the head to smoosh and fold over. I wish that this didn't bother me, as this whole "make pretty" thing is rather silly. This tool works great, as it is. It doesn't need to be pretty. Almost as bad (To me... I'm crazy!) is the way a blade looks when you grind off the folded over part. Then you are left with a misshapen blade, outlined in bright, shiny metal. It draws the eye.
So, I try to hammer the heads back into shape.
Polished tools help. The hammer gets a bit of assistance from an old cold chisel, reshaped and polished. I found it on the side of the road. The idea is to apply force, opposite to what caused the deformation in the first place. The chisel gets underneath, where the hammer won't fit.
Even though the wrought iron is soft, there is only so much that it will tolerate. It would be nice if we could apply heat, but that would draw the temper, ruining the edge holding ability.
The iron may tear, but hopefully it will be a net gain, overall.
It's looking pretty good from the front, back to it's original shape.
Not as nice from the top. Here you can see that the iron has exceeded its threshold of resiliency. Much of this will still need to be filed away. You do what you can.
After filing the nasty parts away, I etch the blade with ferric chloride (PCB etchant), just to get a better look at the grain of the wrought iron.
I love this stuff! Each blade is different, and so beautiful.
The top gets planished to a faceted, hammer finish, then etched, to peek inside.
I didn't want to change the shape anymore than needed, so a little bit of the damage is still there. If I had just used a grinder to remove the distorted metal, I would be left with a flat-top, lopsided kanna blade. This hammering process can preserve much of the iron and come close to regaining the original profile. It does take work.
It isn't apparent from the photos, but the hammered surfaces are actually rather bright. I would like to tone that down, to blend in with the original finish, but this blade doesn't have much original finish, so.....
Birchwood-Casey Super-Blue, gun cold-process bluing liquid to the rescue. You can apply it to small areas, to blend, but the darks might not match. I obviously did everything in sight. Cold bluing is not very durable, and can fade within hours, weeks, whatever. Handling will accelerate the disappearance, but it's easy to reapply.
Something must be in the air today, but the super blue is actually turning blue (often it's black), and I don't really WANT blue, so.......
Rust bluing. We're going old-school!