Recommendation? Etching stainless damascus

NickHFSS

NickHFSS

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Jun 26, 2020
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I have a knife with sandwich of elmax and stainless damascus , I was advised to etch with citric acid , what is the best mix of citric acid and what time should I put it in , basically this is an I want to skip the experimenting and do the workpiece straight up kind of question
 
On most stainless damascus, I use regular FC.
On damasteel, sometimes I have to use dilute muriatic acid (HCl).
Not to say it won't work, but I have never heard of etching stainless with citric acid.
 
+1 for 50/50 FC...I only use a couple different stainless damascus steels though, and that's what the maker's directions say use.
 
From a chemist's standpoint, HCl is an active/strong acid and has 100% ion availability. Citric acid is a weak acid and isn't nearly as active. It would be good for working on a hamon, but I just don't see it for etching stainless damascus.
 
NickHFSS said:
I have a knife with sandwich of elmax and stainless damascus , I was advised to etch with citric acid , what is the best mix of citric acid and what time should I put it in , basically this is an I want to skip the experimenting and do the workpiece straight up kind of question
Click to expand...
Where did you get this from?
 
20% Citric Acid (lab grade) w/v in H2O, old Damasteel:

Can see pattern in ten minutes. Can see color as dark as "for sale etch" on the bar after 3 hours. After 24 hours you can feel the pattern with a fingernail. After 48 hours you can feel the pattern with your fingertip.
I'll see where it goes.
 
I did some research and am surprised by what I found. I guess even an old chemist can learn a few tricks.

Turns out iron is very soluble in citric acid (ferric citrate) Supposedly, a nail will dissolve in citric acid in an hour. It does not oxidize the iron into rust, but actually dissolves it. I have a bunch of Damasteel and damasteel blades I made a while back the=at are ready for sanding that I will have to experiment with. Fitzo's results look promising.

Turns out that is why lemon juice is popular in some places for etching steel and working a hamon.

Even more interesting is that citric acid is used to leech the iron out of gold tailings and ore. In places like Australia gold is usually found in iron rich soil and minerals. Citric acid is also used in water softeners to remove iron from the water.

Final thing I found was that citric acid is very good at cleaning and passivation of stainless steel. It makes it very corrosion resistant. Along with tat it increases the chromium concentration on the surface.
 
Those three carboxylic acid groups in close proximity make it a special molecule. It makes etching accessible in places where things like HCl and FeCl aren't available or the hazards unacceptable. I would think the food-grade material, while not as pure, will work well, too, and will be available wherever people do canning.
 
I regularly use heated HCl to 70C to have a deep etch so light can play with the blade. But I would like to know your results with citric acid. Thanks!

Pablo

Rtp4YhQ.jpg
 
3 days 20% citric acid (aq). Left is as received, brown line was liquid depth. About 3/4 inch right of the line is factory etch and citric acid. The far right inch and a half or so is etch from sanded bright. The depth of the etch is about where I'd have stopped if I wanted to feel every little ridge. Remaining solution is dark brown at this point. Etching continues...
IMG_0332.jpeg
 
Hmmm. This may sound weird ... but what about etching with coca cola? It has a pretty low ph ... i believe from phosphoric acid. Also, phosphoric acid can be bought, i believe, from homebrew supply stores.
 
shqxk said:
I have tried etching with ferric, etching with muriatic first then ferric(Begg recipe). Now I prefer only muriatic acid since its give the cleanest looks.
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I agree, although I want to try finishing with a coffee etch after the muriatic next time. I had really good luck further darkening the dark spots on some 410ss/52100 san mai and I want to see how it works on Damasteel.

Here's my last with just a muriatic acid (diluted 50:50 with water if I recall correctly) etch.
cBvIjXK.jpg
 
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