Damascus Knives & Re-Etchng

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which acid/s exactly is the etchant composed of?
 
Here's the MSDS for Radio Shack PCB etchant--ferric chloride, ferrous chloride, and hydrochloric acid.
 
primarily Ferric Chloride, Joels. I have etched carbon steel and wrought iron exclusively, so I use FeCl diluted with water, around 4 parts water to one part PCB etchant. You would need stronger stuff for any type of stainless. The slower you etch, the more detail you can pull out of say a hamon. You might dip a blade like that for 10-15 seconds at a time in the diluted FeCl solution and neutralize, rinse and polish off the excess oxides 10, 15 or more times. One the other hand, for a realtively shallow etch on my 1084/15N20 damascus like I used for the gyuto I posted recently, it might on ly one or two etches of no more than 5 minutes and a bit of Simichrome or Flitz and some elbow grease to finish that up. I think that I did one 5 minute etch and then a very short 1 minute etch on that gyuto because I removed the nail polish covering the makers mark and etched it lightly just to give it a tiny bit of color. I was VERY bright silver compared to the rest of the blade befoe that second etch, but I just wanted it to be a bit blue-gray, not to show the pattern inside the oval..
 
Uhm, so is it right to say the initial preparation involves polishing the sides of the blades to remove scratches that would otherwise be magnified by the etching process? Would it be feasible to do it with a sufficiently high grit stone (say a 6k) or the sandpaper has some inherent qualities that makes it better at the task? Btw thanks heaps Dave for sharing your knowledge!
 
Uhm, so is it right to say the initial preparation involves polishing the sides of the blades to remove scratches that would otherwise be magnified by the etching process? Would it be feasible to do it with a sufficiently high grit stone (say a 6k) or the sandpaper has some inherent qualities that makes it better at the task? Btw thanks heaps Dave for sharing your knowledge!


Hi Chili,
The etchant will remove some light scratches and buff marks but it's best if you can sand the surface smooth and make it even in appearance before etching. It sucks to etch a blade and find a deep scratch still showing.

I would NOT use stones to do this work. Stones are flat and blade sides are not and you will without a doubt hate yourself for having tried the stone method. Sandpaper is flexible and will go in and out of the low and high spots.
 
Got the message! One day I'll find the courage to etch my Hattori HD... posts like this one are great to boost interest and push ppl to experiment, thanks again!
 
Can you over-etch a knife? If so what are the results?
 
You can forsure over etch a knife. I "forgot" I had a knife in my enchant and went hunting for a week. Now, this is a worst case scenario, but lets just say the blade looked like you pulled it out of a swamp after it being there 100 years. I did manage to salvage some of the damascus, but the acid ate so deeply a 240 mm gyuto I was etching ended up being a petty by the time I ground to clean steel.
 
I am new at this game, but everything that I see says that you can " over etch" a kitchen knife even if you don' t go to the extreme described by Pierre. :lol2: With other types of knives, you might want to etch really deep, especially if you plan to "fill the low spots" by parkerizing or using baking lacquer to enhance the contrast. That might not work so well on knives used for food prep. :biggrin:
 
I finally got around to trying this. PCB etchant was available at my local radio shack, vinegar at target, nitrile gloves and low-lint shop rags, sandpaper, and acetone from the auto parts store, and I already had the glass.

I mixed about 5oz vinegar with 5oz pcb etchant in a med glass jar, and then just cut and wadded up a 6"x6" section of clean rag and dipped it into the solution. I used a pyrex baking pan just as a place to rest the knife and catch drips / run off. I was really amazed at how fast the reaction happens. I bet it would be slower on a stainless knife, but on highly-reactive shig carbon, it was almost instantaneous. In just a few seconds the contrast was super dark and as soon as it looked like it wasn't getting any darker I dunked it in water and then washed it under running water, clean/ cleaned it with a soft, soapy cloth, and rinsed again, and did a final clean and rub-down with another bit of the soft shop rag.

Looks like a great success!! One interesting side-effect is the the areas where the jigane and hagane in the kitaeji meet turned slightly "glittery." Any idea on why? It's not pitting, the surface is still as glass-smooth as when I polished it. Perhaps something to do with the coarse grain structure of the soft iron-like material that shig uses in the cladding?
I'm sure that it will fade as further oxidation / stabilization sets in, but it looks cool.

Some quick phone pics as documentation that "it happened."
IMAG0028.jpg

IMAG0029.jpg


Thanks again to Dave and the other contributors of this great resource thread!
 
Nice Justin :)

Oh and I have no idea what the deal is with the glitter. I've seen this myself but I'm no metallurgist.
 
So I have a question on etching. Can you etch a non-damascus blade black? For example the Itto Ryu black gyuto. Could that be an effect that could be achieved from ferric chloride on some type of Hitachi steel? Or would the etching just destroy the blade? I'm hoping that someone out there with more experience can give me some insight.
 
Can any of you who have done the etching with the ferric chloride tell me the proper way to discard the used acid? It's not something I'd want to toss down the kitchen drain so I'm assuming that there is a way to neutralize it prior to disposal. Or has everyone just bottled it up for future use?
 
Can any of you who have done the etching with the ferric chloride tell me the proper way to discard the used acid? It's not something I'd want to toss down the kitchen drain so I'm assuming that there is a way to neutralize it prior to disposal. Or has everyone just bottled it up for future use?

After mixing it with vinegar as per dave, I just saved it in a glass jar. Since Dave's method for applying it uses the swab-on method, not the dunk-in, you don't contaminate your solution. In the sealed glass container it hasn't seemed to decrease in potency at all even over several months of storage.

If for some reason you HAVE to dump it, I'd just dilute it waaaaay down with water and then run water down the drain afterwards to make sure that you flush it out of any of the traps / elbows.
 
Is that a kagayaki? I achieved a VERY glittery result on that blade.
 
Is that a kagayaki? I achieved a VERY glittery result on that blade.

shi-shi-shi-shig!

Is the kagayaki also iron high carbon steel?

maybe it's something to do with the combination of the crude, impure ore with the refined, fine grain steel?
 
I have tomorrow off. I'm gonna try this. Have a few beaters that could use a bath.
 
I tried this last month on my Delbert. Came out awesome, the second time around that is...

20131113_145018-picsay_zps158477bf.jpg
20131113_144930_zpsed820f75.jpg
 
That looks really aweaone. Del's work is very distinctive; nice job bringing it out. Is that his 01 / L6 stuff?
 
Has anyone tried this on an HD2? i know its not Damascus but i'm just curious what would happen :p
 
Konosuke HD2? It should just turn dark grey/black.

On a different note, had some post-physiology exam fun and etched a tanaka ginsanko 190 mm

IMG_2264.JPG
 
I just did mt Tanaka 240 for the third time last night after my dishwasher decided to scrub it down with a brillo because he "thought it looked dirty".
 
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