Electro etching (or also referred to as saltwater etching) is a relatively simple process that can be done with components that are likely found around your house. This process can be performed on almost any conductive metal to include copper, steel, stainless steel or even brass.

Supplies

A Battery - This can be done with lower voltage batteries but I suggest using a 9v or above for expediency. 18v Rechargeable batteries work very well for this.
2 Wires
Alligator clips
Saltwater
Electrical tape or vinyl
Q-tips

Step 1: Pick Your Design

First you will want to determine what design you will be etching onto your blade. This can be simple as just letters or as complex as intricate knots just remember that if you don't have a machine to cut the design out you will be doing it by hand. A cricut makes this job a LOT more easy for intricate designs but it can be done by hand with a little more patience and time.

Step 2: Clean Your Steel

Once you've established what design you want on your steel then you will need to prep the steel for the transfer. The reason for doing this is that oils from your fingers or leftover materials from the making process may dilute or otherwise impair the effects of etching. This is also just a good habit to get into whenever you do any altering process to the steel.

I've found that alcohol wipes work very well for cleaning the blade but you can use break cleaner or paint thinner as well.

Step 3: Place the Design

If you have the design pre-cut via a cricut then you are ready to transfer it to the blade. If you do not have access to pre cut designs then you will have to cover the area of the steel that you wish to put the design on with electrical tape. It is recommended that you lightly sketch your design on top of the electrical tape to make sure it is what you want before you start cutting.

Step 4: Remove Extras

If you have your design placed where you want it on your project you will now need to carefully remove the spaces where you want the etching to occur. Only exposed steel will be etched so keep that in mind when you are removing pieces of your pattern. (I know I shouldn't have to say that but there are also some ridiculous warning signs out there for a reason.)

Step 5: Hook It Up

At this point you are almost ready to start your etching but you will need to do some prep work first to include:

Get your salt water ready. I have not found that the mixture of salt to water makes a huge difference in etch speed or otherwise but you will want enough salt in the mixture to be effective. I use a coffee cup and fill it with hot water and then put in around 2 tablespoons of salt and mix it well.
Connect your wires to the battery. You will want your positive line to go to the steel you are etching, and your negative line will be your contact point that you use to dab the salt water onto your pattern.

Step 6: Etching Time

Position your work piece in a manner that you can see it clearly but aren't leaning over it directly and also make sure that you are working in a ventilated area. The etching process creates hydrogen gas and chlorine gas which you don't want to be breathing.

Chlorine gas health related facts can be found here

Hydrogen gas health related facts can be found here.

Now attach a q-tip on the negative wire (with attached alligator clip).

Step 7: Dip Dab Repeat

Dip the end of the q-tip into your saltwater solution. You will want to position the alligator clip close to the base enough that it is on the fluffy end but not in your working area.

Gently dab and hold your q-tip onto the exposed steel for a couple of seconds. Don't rub the steel as this may inadvertently remove your template. Reposition and repeat until the whole of the pattern is covered equally. Change sides and or to a new q-tip when the ends of them start blackening up. This is the result of the metals being corroded. You may also notice a black sludge appear during the process and will likely noticed the afore mentioned gases. Just gently dab off the black sludge with a paper towel.

Step 8: Are You Done?

Make absolutely sure that you have etched your project to your hearts content before removing the pattern. Once the pattern is removed, you will not be able to get it lined back up. I recommend going over the pattern at a minimum of 2 times and 3 more if you aren't sure.

Step 9: Are You Done Now?

If you are done and have removed your pattern, you are definitely done. Clean your project with soapy water and dry. You may notice some darker spots within the etch and some lighter spots. The darker spots are the areas of the etch that still have pockets of corrosion in them. The lighter spots are cleaned out or were not etched deep enough.

I've read but cannot confirm that you can darken these spots by utilizing an alternating current (plug in) in the same manner.

You may be able to also darken the etch by using a bluing agent within the valleys of the etched area.

I know there is a lot of content on the interwebs about this particular subject but felt that it would benefit someone in the knifemaking space if I had it here as well. No matter what knife, axe or other project you are making remember to have fun, be safe, and always forge ahead. See content like this and more at The Bevel