I've been going nuts with electroetching lately, it's super fun and pretty simple to do. Best of all, it doesn't require expensive or hard-to-find materials. You probably have most of what you need in your house already. The only things I had to go out and buy were fingernail polish and nail polish remover (a buck each at the dollar store) and a pair of test leads (less than four dollars at Auto Zone).
Before you start etching everything you can lay your hands on, I should warn you that this process produces a gas that is probably hazardous to your health. Make sure you do it in a well-ventilated area!
Got your window open? Great, let's get started.
You will need:
plain white vinegar
regular table salt
fingernail polish (use the cheap kind, you'll need a good bit of it)
fingernail polish remover
test leads (explained below)
small bowl for mixing the solution (I used a bottle cap)
whatever you want to etch (must be a conductive metal that's not painted or anything - I'm using a stainless steel butter knife from the thrift store)
Test leads are a pair of wires (usually one red and one black) with a metal alligator clip on each end. They're used to test simple electrical systems and they look like this:
You'll also need paper towels, and you may want to wear rubber gloves. I don't, but then I don't care if I get nail polish all over my hands. Your call.
The first thing you do is paint your knife blade (or whatever you're etching) with nail polish. You want a nice even coat that's not too thick, I guess like you would put on your nails? I don't wear nail polish, but I imagine that's how it works...
Just paint the surface you want etched. You won't be immersing your piece in an acid bath, so don't worry about covering up the back.
While the nail polish is still wet, use your toothpicks to carve out the design you want to etch. You have to work fast, especially if your etching surface is large, since nail polish is designed to dry quickly. Keep in mind that whatever isn't covered with nail polish will be what gets etched. I've found that designs with thin lines tend to work best, since it can be hard to get an even etch over a large open area.
Let your piece sit until the nail polish is completely dry. Don't worry, it won't take long. Once it's dry, mix up a solution of salt and vinegar in your little dish. I don't measure this part, but a tablespoon of vinegar to a quarter teaspoon of salt seems like a reasonable ratio.
Using one of your test lead wires, connect the positive terminal of the battery to some bit of exposed metal on whatever you're etching. (Traditionally, the red wire is the positive wire, but if you want to be a rebel and use the black wire I promise I won't tell anyone.)
Clip one end of the other wire to the negative battery terminal. Clip the other end to the end of a cotton swab dipped in your salt-and-vinegar solution.
The cotton swab doesn't have to be super drippy, but there should be enough solution on there to make a good electrical connection with the alligator clip. Make sure the clip is attached to the actual cotton bit, not the paper stick farther up.
Touch the wet end of the swab to the lines of your design. It should start to bubble and hiss pretty quickly, and you may see wisps of smoke coming up. Drag the cotton swab slowly along your design. Try not to hold it in one place for too long - you want to keep moving so all your lines are etched evenly.
The cotton swab will start to get pretty grody. That's good, it means it's working. Just dip the clean end in your solution, re-clip the black wire, and keep etching.
I think I went through both ends of two cotton swabs on my knife. I should have timed how long I spent on the etching process, but I didn't think of it until right now. Oh well. Just be aware that the longer you spend etching, the deeper your design will be.
It was hard to get a photo to show it, but you should be able to tell the difference between etched lines and not-etched lines in your design - anything that hasn't been etched yet will still have the shiny surface of the original piece, while lines that have been etched will have a more matte surface.
When everything has been etched to your satisfaction, take some nail polish remover to your piece...
...and go "YAY!"
A few notes:
You may notice the alligator clip that's attached to the cotton swab bubbling and hissing during the etching process. This is normal. It's made of metal, too, and it's being etched just like your piece is.
I've tried using contact paper as a resist instead of nail polish, and I didn't like the results as well. The salt-and-vinegar solution seeped under the contact paper in a few places, so the edges of the design weren't as crisp as the ones I did with nail polish. If you want to experiment with different tapes and things, though, go for it! Leave a comment saying how it went.
If you let your solution sit in your little dish so long that it evaporates, it leaves behind funky square salt crystals.
So that's it! Have fun! Please let me know if any part of this tutorial is unclear, or if you have any questions. Also, if you make something, I want to see!