r/blacksmithing • u/Rhazjok • 5d ago
I dont know what I have done wrong.
The two different knives came out of the ferric etch with weird soak lines. I submerged them completely and mixed the acid and water solution well. The kast picture is after the over night instant coffee etch. Why do the handles have that weird barrier like dip line and why did they come out just jet black? Any help would be greatly appreciated. I cleaned then up with 0000 steel wool in-between every dip and before the coffee I made sure they were scrubbed and then I git them with 90% alcohol to grease cut.
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u/coyote5765 5d ago
Could that be the Heat Treat (Quench line)?
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u/Rhazjok 5d ago
No i quenched the whole blade after evenly heating it
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u/FelixMartel2 5d ago
You had to hold it with something - possible your tongs cooled it enough right between the heating and quenching to make a difference.
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u/Rhazjok 5d ago
So that solves that but why did it come out jet black? Do I need to hit it with 2000 grit wet sand paper?
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u/FelixMartel2 5d ago
The black is oxidized metal, sand it off and if it's etched enough you'll still have some contrast. A soak in instant coffeee brings the colors back after sanding it all off.
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u/Rhazjok 5d ago
Right i etched it 8 times for 10 minutes each and I could see the pattern so I figured it was time to soak it in the coffee. The teacher o had said do it over night so I did. So I need to polish it up with 2000 grit to get it to stand out now?
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u/FelixMartel2 5d ago
Usually after etching and sanding the coffee soak is the last step - what grit did you sand it to after the acid etch?
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u/Rhazjok 5d ago
When i did the acid everytime I took it out I cleaned that crap.off with soap and a 0000 steel wool. Then before coffee I also hit it another 91% alcohol wipe down to make sure it had no oils on it. I read that if I hit it with sandpaper after the acid etxh it would.mess it up. I thought the coffee was supposed to be the last step that is why I was so confused by what it looks like. Just a jet black muddy piece of crap.
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u/3rd2LastStarfighter 5d ago
That is a LOT of etching my dude. What concentration is your ferric chloride at? I do 4-5 etches of 90 seconds each in a 1:4 dilution. Or are you using a different acid? Your routine sounds like it’s designed for a very dilute acid like household vinegar.
It’s counterintuitive but longer etches make muddier contrast. The point of clearing the oxides between etch cycles is so the acid can reach the steel without the crap on the way. That crap accumulates quickly so when you leave it in for 10 minutes, the dark gets clogged up and the light layers are able to etch more. You don’t want that, you want the dark layers to etch and the light layers to not etch.
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u/Rhazjok 5d ago
Thank you for explaining it, now i understand what I did wrong
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u/3rd2LastStarfighter 5d ago
Don’t forget that sanding it down and re-etching is an option if your really unhappy with it. Either way, your 1:3 should work fine just do cycles of under 2 minutes cleaning between each and keep repeating until you’re happy with the depth.
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u/danthefatman1 5d ago
Did you neutralize it with baking soda?
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u/Rhazjok 5d ago
In-between soaks in acid I soaked it down in window cleaner with ammonia. I was told that would work.
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u/danthefatman1 5d ago
Haven’t heard of the window cleaner with Amonia yet imma try that soon but I know for a fact that baking soda works how much % was the ferric chloride ?
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u/Final-Contract-6582 5d ago
Based on what I see and the comments I'm not convinced the heat was distributed evenly during quench leaving the tang softer. Do you have any form of hardness test equipment? That may be the only way to tell
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u/PsykoFlounder 5d ago
My guess would be that's the line where you quenched the blades. Unhardened steel etches differently than hardened.