electro-etch black issue

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dmcmd

Joined
Jan 1, 2026
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Hi all. I built an electroetching machine the other day. It's 24V, both AC and DC, 2 amps. It works great in terms of removing metal, but I can't get that dark black finish that I see on so many youtube videos. I tried both DC polarities - only electrode negative actually etched. I tried electrode positive just to see what would happen, and the answer is pretty much nothing. I tried DC followed by AC. I tried AC only. Really nothing got me that dark etch that I'm looking for. Any hints?

BTW, this is on a piece of 304 stainless I had sitting in the shop.

left side: AC only
right side: DC followed by AC
ASF7oqH.jpeg


left side: DC only
right side: DC followed by AC
HwvSgmf.jpeg
 
I remebered reading some posts in the past. I posted a quote from Stacy and a link to a couple threads ... maybe they will help.
Stacy E. Apelt - Bladesmith said:
Here is how etching works:
1)The ETCH is caused when DC moves through the blade, taking electrons and metallic ions in one direction. The current for etching is called "Reverse Current", which means the current is flowing from the blade to the pad. This pulls out metal ions and slowly erodes away the metal where the stencil leaves it exposed. The surface exposed is grayish metal. Under a microscope it looks like a million little craters. The pad gets the ions which oxidize there and usually make the pad black. How fast, crisp, and deep the etch is a factor of having the right combination of parameters ( see my earlier post #4).

Once the desired amount of metal has been removed, the recess needs to be made darker.

2) The MARK is made by using AC current. This changes direction 60 times a second, repeatedly removing and then re-depositing the ions in the bottom of the etch. Because this causes the metal ions to oxidize, the bottom turns black. The voltage and amperage as well as te amount of time will determine the quality of the MARK. Too much can start to "lift" the black out.

So, ETCH first with DC to remove the metal, then MARK with AC to blacken the etch.

One technical reason to not switch back and forth is that the oxides are somewhat non-conductive and may actually make the etching slow down or stop.
Click to expand...


A

Thread 'Etching/marking problems - black just rubs off...why?'

I've built 2 different homemade etchers, following the "poor-man's etcher" plans on dcknives and then the more sophisticated Chris Crawford design. Both are 12v (I followed the advice in a thread here to do the logiudicecustomknives.com modification of the Crawford design to just 12v as 24 apparently fries stencils). Both have DC for etching and AC for marking.

Using both, I've used the standard SCE-1 electrolyte as well as a saltwater solution. Both give me great etching (DC). Both give me nice marking (AC) with a nice black mark. But as soon as I pull the stencil off, rinse, and wipe -...
C

Thread 'Chemical/ Eletro Etching problem!!'

Hey there fellow Bladesmithy's...I was just gifted an electro etcher for Xmas, and I was super excited to start adding my touch mark to knives buuuuuttttttttt..... I am not getting a deep etch. I have a "knife dog,' KD-30 machine with SC-44 solution and a stencil from IMG. I have tried to etch two different knives: 1 made from a rasp and another made from 1095. I get a dark mark but I can just about wipe it off, then you can see a faint etch in the steel. I have tried different intensities and it just gets darker and not deep etch, I would like. What am I doing wrong? Should I be...
 
JJ_Colt45 JJ_Colt45 Thank you for your reply. I read through the links you posted. There's good info in there.

It may be my technique. I was just dabbing fairly quickly rather than holding the electrode in position for a few seconds. I'll try some other techniques. Maybe the windex... I saw a video on youtube using that.

Darren
 
Get a bottle of commercial electro-etch solution.
Make sure you blot the pad to just barely damp. Too much electrolyte is not better than just right.
Set the control for ETCH (DC blade to positive clip) and etch for the desired time (start with 20 seconds total time). Press down firmly, but not hard for 5-10 seconds. Lift for 1 second ... repeat. Do this 3-5 times (experiment on scrap steel of the same type).
Place pad on stencil and DON'T move the pad. Switch to MARK - AC for 10 or 20 seconds. Do tests to see how long you need to MARK to get a good black mark.
If you have too much electrolyte on the pad the MARK will often have a "halo" around it. Use a very fine grit paper on a hard backer to gently rub away the halo and leave the mark crisp. I use the 3M 2000grit (pink) or 4000 sheet (mint) on a small piece of micarta for this.
Be sure to neutralize and clean the blade well after etching.

99% of etching problems can be solved with the below info:
There are several common issues with etching:
1) Wrong polarity - Make sure the pad is attached to the negative terminal and the blade has the positive clip.
2) Wrong current - ETCH on DC, MARK on AC. Etch in pulses of 5-10 seconds. After three or four of those, switch to AC for 10-20 seconds ( test on scarp to determine exact times)
3) Wrong voltage/current - You need a unit capable of delivering 1 amp continuous at 12V. 12V/24V and 2 or 3 amps is even better.
4) Too much electrolyte - The pad should be just barely damp with the solution. It should be blotted on a folded paper towel just before applying over the stencil.
5) Too much voltage - If your unit has variable voltage start around 12 volts and do some tests. Too high voltage can "burn" the mark.
6) Wrong Electrolyte Solution - If the above parameters are right almost any electrolyte will work. The commercial ones do seem better, though.
 
You need to hold down and press slightly like Stacy said. I use the SC-1 electrolyte on everything from stainless, tool and carbon steels and it worked great.

My homemade etcher would also let me etch jimping in the spine, too! I would print out a cricut stencil of capital "I"'s and use the DC to etch. Took several minutes, cycling on and off every 30 seconds or so, but it worked!

If the felt pad gets gunked up, it may prevent a good etch or blackening, too.
 
Go to USA knifemakers and do a search on "Electrolyte SC-44" and you'll see what you need. Either the SC-44 or SC-35 should work. OR, do the same search on Amazon and they'll pop up. Going direct to knifemaker's is a tad cheaper.
 
I got a new bottle from Pops of their SC-E1 and got my lasers going like a month after...lol. Never fails! Quickest way to find something in the shop is to buy a replacement! LOL.
 
304 isn’t easy stuff to etch, much less get a black mark. I have a commercial etching machine, and new commercial electrolyte for etching stainless, and some older stuff for black marks in stainless. I can get either mark pretty well on AEBL, 12C27, and RWL34, but getting an etch on some 304 (around some 1.25 diameter bar) and trying to then blacken the bottom was a real PITA. Took longer and more power than any blade steel I have used so far just to get the etch, and the mark was neither particularly black, nor permanent.
 
Thank you guys for all the responses. You are a wealth of information.

Looks like I'll have to get some real electrolyte solution. I was kind of hoping to avoid that since I'm cheap. I feel like this stuff could be made at home...

I'll also try some AEB-L I have after I cut my first knife out of it here pretty soon...

Darren
 
I’ve seen videos of notable makers using Birchwood Casey Brass Black in their logo after etching. Jax Black Darkener is another one that might work. I haven’t tried either personally but intend to.

Black paint works but comes out if you clean the blade with acetone and other cleaners.
 
ScarFoot said:
I’ve seen videos of notable makers using Birchwood Casey Brass Black in their logo after etching. Jax Black Darkener is another one that might work. I haven’t tried either personally but intend to.

Black paint works but comes out if you clean the blade with acetone and other cleaners.
Click to expand...

I've wanted to try it also, but haven't yet...
 
Here's an update for you guys:

You were all correct. The electrolyte solution was the issue. As I said above, I wanted to make my own solution. I didn't want to have to rely on buying it somewhere. So I got on ChatGPT and researched what electrolyte solution would be best for what I'm doing. We decided to make two solutions: one for etching (ammonium chloride, glycerin, and water), and one for marking (potassium nitrate, glycerin, and water). The issue with marking is that you need to make oxides on the steel, and nitrates will do that.

Here is the result:
ya2BYOk.jpeg


It could probably be better, but I'm happy with the progress I'm making.
As an aside, when I hit this with a surfacing belt on my grinder, all the black gets worn away. That's what happened to my initials on the right side of the photo. On the left etching, I just sanded with 1000 grit after the etching and didn't use a surfacing belt.

So there you go. You guys hit the nail on the head. But I wanted to show you that you can make this stuff at home...

Lastly, here's a teaser of what's going on in my shop right now...
That's 12awg Kanthal A1.
il5TP5e.jpeg
 
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