Instructables
Picture of Etching Knife Blades

This instructable covers how to etch a knife blade.
Modern knifes are often made from stainless steel and other corrosion resistant materials. To encourage etching electricity can be used. Don't worry, 9V is enough!

Etching is different from engraving. Engraving is usually scratching fine lines into the surface of the material, whereas etching chemically removes material, possibly until a hole is created! Etching can often go deeper than engraving.

I should mention that I got the information on how to do this from this site , it came up from a google result and gives you the basic info on how to do it. I've added pictures of my experience to help you along the way

 
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Step 1: Materials

You're going to need:
-nail varnish (paint may do instead),
-acetone (nail varnish removed or other cleaning solvent might do),
-cotton buds,
-water,
-salt,
-a 9V battery,
-croc clips,
-a scribe or pin,
-the object to be engraved,
-a dish to do it in.

Step 2: Coat the blade

I practiced on some cheap snap off blades and found that any uncoated material near the etching area became etched and pitted. So to be on the safe side I entirely painted the blade with nail varnish.

Step 3: While that's drying...

Get the dish you intend to do this in (not your mum's best cookware, so scrap would be better), add the water and add some salt. You want to make salty water. I'm assuming the saltier the quicker the reaction. This might be an interesting experiment to carry out with varying concentrations of salt and measuring etch depth over a set time.
I just added a bit of salt, don't think I got anywhere near saturating the water, just enough to make it salty - a good electrolyte.

On the knife that says "Velasquez" it looks like the etching is darker than the one that says "Alice". How did you achieve that?

I use the iron on toner technique.

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lasersage (author)  casey.mckelvey16 days ago

Nice one, that looks really smart

Lucky7x71 year ago
This is what i was able to do...
lucky.JPG
Excellent..!
Regulated 12v power supply 13.8V 2.5A, Salt and red wine vinegar solution, Qtip, Nail polish,Aluminum toothpick, to draw designin nail polish, 20 sec per area that head of qtip covered
awessome idea i'm gonna do it right now!!!
do you have to apply that voltage or you could do that with a car 12v battery? can u use more or less current? and what are the results os changing the voltage?
thx
rockettman3 years ago
How long did you rub the cotton bud over the etching area, 30 seconds, 1 minute, 10 minutes?
lasersage (author)  rockettman3 years ago
I did it for a minute or two maximum, as I said in the instructable, the best result were from less time. Less is more. Doing it for longer meant the nail varnish degraded round the edges a bit and the whole thing got tattier and ugly. Less time gave a sharper image, though not as deep.
I'm afraid you really need to experiment for your self as I haven't specified amount of water to amount of salt ratio, nor do I know which battery your using I can't be more specific. All this will affect how long you need to do it for.
It certainly shouldn't take as long as 10 mins.
So etching out say thin intricate designs completely from the metal is very unlikely?
lasersage (author)  Basement_Craftsman2 years ago
I take it your referring to eating right through the metal?
I guess you could but I think you'd have poor resolution. If you can imagine the nail varnish resist only work on the surface. Once you've eaten in to the metal a little, the side walls of the trench you're etching aren't protected by the resist. This would allow the edges to eat away, possibly even undercutting the initial design.
If you're trying to do it to something very thin it might not be a problem but I suspect anything over about 0.1mm is going to show noticeable pattern degradation. Experiment I guess.
Also don't forget the middle will drop out of characters like a, e, o, p, d, 0 etc.
You'd have to have supports like when you stencil
Tried this last night and I was very impressed. However I used a an old FRS radio wall wart (7.5v, don't remember the amps) instead of a battery.

Very cool. Thanks!
Let me clarify a few things here. I am very weary of the danger here and, as such, took a few precations. I never touched the water. Also, I insulated the metal being etched and the cotton swab with electrical tape where I was holding them. I have no desire to be shocked. :)

I'll check on the amps when I get home tonight and let you know.
worried about the "danger" from a 9V battery? really?!
I'm a little late to this discussion but just recently came across this thread and thought I would add my 2 cents.

Typically the ESD (electrostatic discharge aka ‘Static Electricity’) 'human body model' testing is 8,000V touch and 15,000V air gap. This is used to test electronics for susceptibility to ESD. You rub your feet on the rug and zap a sibling... that's a very respectable amount of voltage that you just generated.... but there is essentially no current and "Current Kills"... It only takes something like 6-20mA (don’t recall the actual amount) through the heart to kill. Wall warts typically supply 250mA to 2A. Batteries will source all the current that they can. As long as there is minimal resistance along the path of electricity and you send 20mA through the heart... DANGER is possible. Using an electrolyte rich fluid (like salt water) and placing your hands in a bad way, it could very well put you at risk. Granted your skin will act as impedance... but it all comes down to Ohm’s law.

What I think ‘_soapy_’ and ‘laserage’ are discussing further down is if a bad setup is there and the cheap little wall wart is past its nominal operation… it could have problems and source more power than a battery could. Given how cheap those things are, that is definitely a possibility.

Like I said, my 2 cents... ehh maybe my 1.5 cents. =)
I wondered if a wall wart would work. Could you let me know what amps yours has so I could try to match it with one from my collection?

In your experiences, is this more of a slow swipe over the blade or a several minute operation to get the etching deep enough?
As ever, plugging conductive things into water and putting your hands on it is a bad idea when it is connected to anything at mains voltage, even through a $2 Chinese made wall wart.

Just use a battery or two, it is far safer. Also, you might kill the wall wart if it can't put out enough current.
lasersage (author)  _soapy_3 years ago
I've got to agree with soapy here. In no way do I condone putting your hands in water with a piece of equipment plugged into the mains. Personally I'd go buy some batteries rather than risk it. I know it "should" be safe but the consequences of things going wrong are just to serious.
Good advice. But I don't have a spare battery. And even I did, I would insulate myself from the water anyway (http://www.youtube.com/watch?v=P11WbduMKhY).

And I've got such a pile of wall warts left from old cellphones and CD players, I'd be okay roasting one or two to make a cool blade like these.
heathbar643 years ago
this is great! I've been interested in etching tools etc, but I'm no chemist. Salt water I can handle.
I had to try this out as soon as I saw it!  Very cool.  Instead of scratching out the design I printed out the design on sticker paper and cut it out with an exacto knife.  The results were impressive but I feel the need to clean the metal prior to etching it can't be stressed enough.  I can see all the flaws where I didn't clean it well enough.  This idea rocks! thanks for the instructable.
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What did you use for the orange just paint or lots of nail varnish?
just nail polish
lasersage (author)  dave spencer3 years ago
wow nice one, I think your results are better than mine!
killbox3 years ago
Washing Soda (sodium carbonate) might work better than salt, Ive used it as an electrolyte with electricity to remove rust from something. (by reversing the + - you can get the thing on the - terminal to gain ions and free up rust, and if you put a chunk of junk rebar on the + it can supply the free ions)
jeff-o3 years ago
Nice and simple!

If you want to move up to etching simple graphics, you can use the toner transfer method (the same as PCBs) to transfer toner to the blade for use as a resist.
lasersage (author)  jeff-o3 years ago
I like the sound of that. Must give it a try.
EmcySquare3 years ago
Good Job !!!

When I do the etching to my knifes I use a professional stencil that is cheap if you plan to do the same logo on all of them.
Instead of the varnish you could also dipthe blade in liquid candle wax.
Another way is to iron a reverse printed image on it, but I have no experience in this.

As for the polarity:
- Positive to the blade: removesa bit of steel so the image is engraved
- Negative to the blade: electrons flow the other way round so they oxidate the pattern magint it black.

So you can use them both in this order if you whant to have a deep (microns) engraving with black content.
lasersage (author)  EmcySquare3 years ago
I like the candle wax idea. It would certainly be easy to work with.

I didn't have much luck reversing the polarity, it just seemed to lift all the nail varnish off. Further investigation needed on my part :)

I guess you can make the resist/nail varnish out of any half decent insulator that is easy to apply, pattern, and then remove. Candle wax would do away with the need for acetone as well!
Reversing the polarity will "clean" the blade quite effectively. This is why the nail polish gets sloughed off.

I'm going to try this using vinyl transfers rather than nail polish as I can CNC that far more easily than I can CNC engrave a curved steel blade.
lasersage (author)  _soapy_3 years ago
wish I could CNC anything. Got a bunch of steppers out some old printers. Its my project for next year :)
This is quite common on knife making forums, good to see it here. Many home builders of firearms also use this method to add etching to various firearms. On the AK Forum there are members that make custom stencils for selector markings for various countries Kalashnikov rifles that people rebuild for their collections.
FOXfire09253 years ago
simply amazing, i never thought of it this way! if i remember it right...

NaCl = Table salt


Electrolysis of Aq. NaCl

+end = Cl
- end= Na

the chlorine gas is bubbled through the cotton swab with the water which would equal Hydrochloric acid (HCl) because so little voltage is applied it is a weak dilute acid, but still strong enough to eat the steel a little to make etching in the steel. which would come out to equal ferric chloride.

there is no solution at the negative end. so there is no hydrogen production... (sodium reacts with the water to form hydrogen)

I cant believe i never thought of this! good find!
lasersage (author)  FOXfire09253 years ago
Physics I can do, chemistry I'm not so hot at. But you gave me the words "electrolysis of aqueous sodium chloride" and google turned up this which totally confirms your post (I think). Makes for some very interesting reading. Thanks for the info
yah that link did, but very little because it showed the reaction inside a tank, which would produce NaOH (sodium hydroxide) and HCl (hydrochloric acid) but the reaction here doesnt have any sloution at the negative end, so only HCl is produced...
but anyway youre welcome for the info :D
Err, both are made, and in equal amounts. That's how the transfer of electrons works! However, the amounts are tiny and they react together once you cut the power, of not before.

Sodium reacts with water to produce Hydrogen and NaOH.
Chlorine reacts with (and is also very soluble in) water to produce oxygen, chloride ions and weak solutions of HCl.

NaOH and HCl react to form... NaCl and H2O, so completing this particular circle of life.

The 'lectricity is all that parts the NaCl into Na and Cl in the first place, and once spent, it quickly regains electronic equilibrium by reacting again.