Introduction: How to Tattoo a Knife Blade W/ (Proper) Metal Etching

Today I am showing you how to Tattoo a Chef Knife Blade, using a 9v battery and few tablespoons of salt.

The Tattoo process we are using, is called METAL ETCHING and it is extremely powerful. A chef knife blade is usually very very hard but, with just a 9v battery and some patience , we can tear it off.



First off, I am covering the blade with tape. Any tape works, as long as it is sturdy and waterproof.

If you still have the handle on your knife, which is probably the case, then leave a small part uncovered, as close as possible to the handle.

Then, with a utility knife, I am cutting out a test design,



Fill up a glass jar with water and add 2 tbsp of salt per liter.

Dip the blade in it. warning : only the design and the tape-covered-part must be submerged.

You also need a sacrificial piece of the same metal. In my case a stainless steel fork from which i scraped any varnish off.

Connect an alligator clip to a dry uncovered part of your blade, and another one to the sacrificial piece.

For the record, I bought a dozen of those clips online for just a few bucks.

Place this setup OUTSIDE, and then, using a fresh 9Volts battery, connect the BLADE to POSITIVE and the Piece to NEGATIVE.

The reason why we place it outside is SAFETY : There is a small gas emission which is not desired indoors.

You can tell it’s working when you got bubbles going on. 15 minutes are usually enough for a small design, with a brand new 9v battery.


Picture of CLEANING

Out of the bath, give it a quick rinse and remove all that tape. You can see, The design is now encrusted in the blade. I like how dark and rough it is.



Right, having my name on my blade is cool but... Let’s bring that to the next level. I say we tattoo the whole thing.

Again. Cover the blade with tape. Cut off your designs, and proceed with METAL ETCHING.

Quick notice : That 9v battery is not powerful enough to tattoo the whole blade in one GO. So I am doing it a small surface at a time, about 2 inches square.


Picture of FINISHING

I admit It took me some time, but at the end, this is what I got : A CUSTOM BLADE with my own PIRATE TATOOS on it.

So guys that’s it, I hope you enjoyed this DIY action. I would suggest for your first tattoo to do it on a test blade, that what I did, just to see how it works practically.


_-_I_-_ (author)2017-11-08

You can do a etching chemical with a industrial hydrochloric acid and industrial hydrogen peroxide in les than 30 seconds, without battery ;-)

pscrace (author)2017-05-07

An old mobile phone charger works well for electrolysis just take the phone plug end off and put on some crockadile clips on

Pauleee (author)2017-03-17

You actually do not need a piece of stainless Steel for the negative pole. It is possible with nearly every piece of metal, but using stainless Materials like Stainless steel, copper or silver will lead to a higher efficiency

Modern Rustic Workshop (author)2016-10-24

This is really cool! Does anyone know if you could also hook up like a battery charger or like a big car battery to etch this? That way you wouldn't have to wait very long and buy a bunch of 9v batteries.

Technically you ould use any DC Voltage Source. The Voltage Should not be too high for security reasons (my recommendation: max. 30 V), but also not too low. Good chargers usually check wether a battery is connected, and a car Battery dies when the voltage drops below ~10V. I recommend using a transformer from an old external Hard drive or something similar.

Try running multiple 9v batteries in series for better etching power.

Ahhh! That's smart!

I've done this with a car battery charger but you can get way too much current going through if the piece is large enough and it will etch way too fast and the current agitation can pull of your resist.

I now use a plug in 500w transformer that works really well.

Thank you!

wall wart from old answering machines etc.

Orange robot (author)2017-02-06

Nice... Can someone explain how this works?

Skorekaj made it! (author)2016-10-31

I had a go, and made a little triangle. worked a treat. Thanks for sharing. i iwll now try and do the reverse :)

Modern Rustic Workshop (author)2016-10-29

You should try this on the huge pizza cutter you made with Jimmy Diresta!

WolfgangS14 (author)2016-10-27

Saltwater forms chloride gas Cl2 (from NaCl), which is extremely poisonous.

Better use sodium carbonate, Na2CO3, which is available at a pharmacy

Shadenf made it! (author)2016-10-27

This is awesome! Thank you. This is the first Instructable I have seen and been able to do on the same day without having to go out to source materials.

RichardB320 (author)2016-10-27

Worked but didn't etch on the kitchen ax I wanted to tattoo as a present for a friend of my. (Did got some of the coating from the ax).

throbscottle (author)2016-10-25

Nice work. Always good to see someone achieve a good effect with (relatively) low tech :)

I was just wondering if the same technique could be used to sharpen files - usually done with an acid bath, so this would be way safer! Suppose there's only one way to find out...

Questor (author)throbscottle2016-10-26

use vinegar instead of salt water

markturik (author)2016-10-25

now that i have a nice etched surface how can i color it? like reversing the process with a metal that gives off a pretty color, of a dye, or gun blue, just as a thought. thanks

Questor (author)markturik2016-10-26

reverse the polarity and use a gold sulfate, copper sulfate solution . . . google

Willyd57 (author)2016-10-26

You can use a car battery charger to replace the 9 volt battery. that way you have plenty of power.

Willyd57 (author)Willyd572016-10-26

I should add that the car battery charger needs to be on trickle charge so you don't have too much power and melt the wires or worse start a fire!

rbeech1 (author)2016-10-26

Seems that your polarity is reversed when compared to the de-rusting process.

YS Creations (author)2016-10-26

That's awesomely cool. Going to have to give this a go sometime.

FlavioM2 (author)2016-10-25

Only a warning, i read somewhere else that when you use a stainless steel as electrode you may end with hexavalent chromium on water, wich is extremely poisonous... I'm not an expert, so if someone with chemical knowledge could confirm that, it will be cool (and safer).

cavalier19 (author)2016-10-25

Neat idea. Will try soon.

solis93 (author)2016-10-25

Excellent! Well done.

LarryC57 (author)2016-10-25

Very cool! I've used a similar process (but not quite the same) for taking rust off old tools. That also works amazingly well!

bornready66 (author)LarryC572016-10-25

I have a bunch of rusty tools that I found and would like to know how to clean them up.

Donkey_99 (author)bornready662016-10-25

Hey there, there is a process called chealating where you leave the tools in a bath/plastic bucket etc of molasses and water (5-10% molasses) leave it for a week and Hey Presto! no more rust. It is alot gentler than salt baths on older tools which are a high carbon steel. Does leave them a little black but can be cleaned then painted. May also blacken the wooden handles so take off if you can (planes etc). It was covered in an issue of Australian Woodsmith about a year ago. A quick web search will yield results A mate used a water tank and did car panels too.. Just a case of more molasses (he had some hungry horses!)

HarapW (author)bornready662016-10-25

Taz-Hood (author)2016-10-25

Thank you, Alex, for a very cool experiment and Instructable. Would one of you smart people be kind enough to explain why this works (especially with something as hard as stainless steel)? Is it like reverse electro-plating, with the knife's molecules being transferred to the sacrificial fork? Would this ruin the temper of the blade? (That last question is pretty stupid, I realize, but I just don't understand the chemistry or physics of this, and I would not want to ruin a $300+ Busse knife.) It is amazing that you are getting such a deep etch with just table salt for an electrolyte (?) and a "transistor radio" battery for a power source. (You have to be pretty old to remember that 9V batteries were developed to power small, plastic, pocketable transistor radios, which were all the thing in the '50s and '60s. LOL) Also, would this work on any metal, and why does the negative (fork) have to be the same type of metal? My favorite element is tungsten, and it would be fun to etch some of my less-than-show-quality pieces with the word "Tungsten" and/or "Wolfram" and its symbol in the Periodic Table, "W." I've got some pure tungsten anodes from movie theater projection bulbs (thank you, eBay) that I could use for the sacrificial side of the process. Thank you in advance for any help you can offer in better understanding the process and whether this would work on a big ol' chunk of tungsten! I truly appreciate it.

AndyW63 (author)Taz-Hood2016-10-25

You are correct that this is basically reverse electroplating, as the current moves from one side to the other the ions break down the bonds in the metal and pull it into the water. The metal on the other side doesn't matter, I use a plate of steel and it works with every metal I've tried.

I have done this with steel, brass, bronze, and aluminum so far.

It shouldn't mess with the temper because it doesn't raise the temperature of the steel to any of the critical temperatures.

ChrisM367 made it! (author)2016-10-25

Je l'ai fait sur mon opinel et j'avais protégé la lame avec du vernis à ongle plutôt que du ruban adhésif

manofsteelinstructable (author)2016-10-25

How do I ensure the tape is waterproof?

MatH2 (author)2016-10-25

Rust? Bacteria?...

SporkyRat (author)MatH22016-10-25

I would definitely rub it down with some food-safe oil every time you use it for something wet, and clean it well each time (but that's a food safety thing anyway).

Eddiecar2 (author)2016-10-25

a car battery trickle charger does the trick

davidhalfpenny (author)2016-10-25

I picked up a tip from a guy who teaches etching for printmakers. For very fine details, the bubbles can become a problem. No Bubbles = Better Detail. So if you keep the current down to the point where the gasses can dissolve as fast as they are formed, the bubbles stop but the etching carries on (slowly). OK it takes longer, but that doesn't matter as much as it seems because you no longer have to stand over, it brushing bubbles away with a feather. The simple way to keep bubbles down is to dilute the salt and/or move further the electrode from the knife. For something large or tricky, you'd need electric control gear - but nobody promised us Free Lunch every day :-)

davidhalfpenny (author)2016-10-25

To people who wonder about bigger power supplies - Take Care! A car battery can melt your knife (but would probably melt your wire long before). I use a "Bench Supply" which has a knob that controls the Current, and therefore automatically adjusts the Voltage as the conditions in the bath change.

FARooLAND (author)2016-10-25

La vidéo est bien cool et l'idée aussi. En plus, tu m'as décomplexé vis à vis de mon accent en anglais. Bref Merci.

Fuzzy Monkey (author)2016-10-24

I HAVE to try this! SO cool!:)

Learnjewels (author)2016-10-24

I to would like to know if anyone has tried a car battery.

gizu_one (author)2016-10-24

Wow, interesting instructables and sympathetic presented. I will definitely try it. I have a knife of three layers steel. "It consists of a hard core layer of rust-resistant steel with about 0.75% carbon content and two lateral layers made of tough 18/8 stainless steel." So I think it should work too. :D

offseid (author)2016-10-23

That is super cool. Favorited this one to try it later!

sammykim (author)2016-10-23

so lovely information ^^ thanks mate!

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