Chemical Sharpening

[FortyTwoBlades]

I've heard a myth that some Japanese natural stones chemically affect the edge during sharpening, thereby providing finer finishes than what expected from the apparent grit sizes.

Emphasis on myth. If they have any chemical effect it may bring out the appearance of a hamon in the blade being worked, but it sure isn't improving the edge left by such a stone.

 

[DeadboxHero]

Emphasis on myth. If they have any chemical effect it may bring out the appearance of a hamon in the blade being worked, but it sure isn't improving the edge left by such a stone.

Exactly what Benjamin said, it works abrasively not chemically, popular for helping bring out the contrast between soft and hard steel on bi-metal blades with a "kasumi" or also can polish a "hamon" which is a transition line between hard and soft steel on a mono steel blade with a differential HT using clay at the spine.

 

[Hairy Clipper]

Way back in the 70s we used to send sheet metal files out and have the acid dipped to sharpen them.It did a very poor job but was common in the auto body trade .Yes we had cars back then. WB

Mine was a 1935 Chevrolet Master DeLuxe 4 door sedan with suicide doors front and back with an AM radio that had the antenna under the running boards. The wheels were not wire spoked they were something new called artillery wheels it also had knee joint suspension.

Blades: Hamon??? I had to look that up! More continuing education for an old dog.

 

[tiguy7]

Hydrogen embrittlement can be prevented by baking the parts after they have been exposed to the Hydrogen. I think 1/2hr at 350F does the trick.When acid sharpening files (with HCl), the teeth were not as sharp or uniform as the original, but the alternative was chucking the file.

 

[drail]

Files are not that expensive. When they're trashed - replace them. NOTHING cuts like a new file. I cannot see how acid could possibly "sharpen" an edge.

 

[mycough]

Marcineks post explains why this works so well on fish hooks.
After mechanically refining the point it is chemically refined and sharpened BECAUSE it is the thinnest part of the hook.
All i know is if I get too close to one it ends up stuck in a finger or thumb.
Actually I know one other thing... They go through the bony mouth roof of a small mouth bass pretty darn well.
I need coffee, have a great day guys.

Russ

 

[ToddS]

Normally, etching is "isotropic" meaning it removes metal in all direction uniformly - so if you etch away 5 microns, your "sharpest" feature would have a 5 micron radius.

What you need for sharpening is "anisotropic" etching - in principle this can be achieved with electric fields. It's a common technique for making sharp tips.

 

[HeavyHanded]

I wonder if this couldn't be used specifically for burr removal, or use a layer of chemical on top of the abrasive surface in an assistance role.

 

[ToddS]

I wonder if this couldn't be used specifically for burr removal, or use a layer of chemical on top of the abrasive surface in an assistance role.

That's called CMP - Chemical Mechanical Polishing.

Mud/slurry accomplishes this mechanically. The rolling grit particles soften the steel and knock off the weak steel at the apex.

 

[HeavyHanded]

That's called CMP - Chemical Mechanical Polishing.

Mud/slurry accomplishes this mechanically. The rolling grit particles soften the steel and knock off the weak steel at the apex.

Well, my waterstones are a whole lot easier than wetting my stones with acid, so that's nice to hear!

 

[Wowbagger]

Hydrogen embrittlement

I was going to mention this.
I have seen it where chrome plating has been done to welded parts.
The parts failed at the welds (right through the weld rather than around the edge of the bead . . . which happens when the parent metal is thin and the weld puddles too thick and bulbous). The effected parts had to be recalled. The welds were good but the bead metal had been effected.

I was on the receiving end of the parts (not on the fabrication end).

 

[Allan DeGroot]

The main Reason HCl works so well on clogged files is because Hydrochloric acid vigorously attacks Brass (More specifically the Zinc that is alloyed with the copper) and aluminum as well as converts Ferric Oxide (Rust) into Ferric (II) Chloride (Responsible for that virulent yellow color of the acid bath after putting any rusty steel into it.)

But it doesn't actually make the file sharp again, it just removes the foreign material that is "clogging" the file.
And as someone said above it is preferable to the alternative, Chucking it and buying a new file.

BTW "Hydrogen Embrittlement", several racing sanctioning bodies (CART USAC & NASCAR) have very specific rules about baking suspension components between steps in the plating process to reduce the threat!