My friends and I recently purchased personal "choice beverage" containers, made of stainless steel. They have a nice texture to them, but there is a little square in the front that is mirror smooth. It was just begging me to have something engraved on it, so after much thought and Internet research, I settled on giving electrolytic etching a try. I was inspired by Steampunk, an Instructables.com tutorial, and this guy's Galv-etch tutorials.
The main idea is to cover up all the surfaces that you don't want etched, put the metal in very strong salt-water, and run DC current from another piece of metal, through the water, over to the metal that you're etching (which will also be in the water). The current causes a chemical reaction to happen on any of the exposed surfaces, which eats away at the metal, leaving you with an etched design.
I decided to etch the three letters "XYX" into the container. It's an inside joke. So I proceeded to make a black square in Photoshop, and then put the white letters inside of it. I made a couple of different sizes on the image so I could see which one fit best. Then I printed the image on the glossy front cover of Forbes magazine with a laser printer (HP Laserjet 1012, but I think any one will work). The idea here is to transfer the toner off of the magazine paper on to the steel, where it will serve as your mask.
My first attempt I just used an iron to melt the toner to the steel, but I got poor results when I removed the paper. Maybe I soaked it in water for too long and it actually softened the toner and the paper (I only wanted the paper softened), maybe the toner hadn't been completely melted down, or maybe I just wasn't careful enough. Either way, the lines were quite worn and not straight at all.
I tried again, this time ironing it on and then putting it in the oven at 375F for 10 minutes. I left the door open a bit and put the top of the container near the crack because it has a plastic piece attaching the lid and I wanted to keep the temperature of it as low as possible to avoid melting.
After baking, I soaked it water for 20 minutes, and then peeled of the first layer. You could definitely make out the outline of the letters, like this:
For reference, the whole mask is slightly less than 1 inch wide. Another few soak and peel cycles and I had this:
You can see that I may not have been careful enough, as a large portion of metal is bare instead of black. I also left some of the extra paper fibers on, as I figured they wouldn't hurt anything. So here it is dry:
Now, how to touch it up? I remember reading that it is possible to simply make the mask using a permanent marker, but that did not seem highly reliable to me, so I grabbed a bottle of clear fingernail polish and went to work. This was very tedious (20 minutes?), but I think this layer helped a lot. I ended up covering all of the toner with it, although it probably doesn't look much different in this picture:
Then I covered the rest of the container in wax to complete the mask. I used paraffin wax from Wal-Mart; it's right next to the Jell-O. Make sure you boil a pot of water and then melt the wax in a container floating in that water, because if you heat the wax directly it could burn just like a candle--a big candle. I dipped some of the container directly in the wax, but did most of it by pouring on spoonfuls of melted wax. Again, be careful, because it looks just like water but is quite hot. Remarkably, I didn't burn myself.
After I covered everything but the small area with toner and nail polish, I decided I might as well cover that in wax too, and then cut out the letters. In this way I would have three layers insuring me against erroneous etching. Cutting the letters out of the wax was also very tedious, taking probably a good 30-45 minutes, but I think worth it. (Even though it doesn't look that sharp in some of these pictures it turned out fine.)
So I then assembled the electrical portions. I used a power cube, affectionately known as a wall-wart, to power the operation. It is rated for 12V at 800mA. You can see below that I used a piece of angle steel which I hammered flat for one electrode and the container for the other. They are about 3/4" apart.
Of course this is the sloppiest part of my project. The only wire I could quickly find was some coaxial cable. It has a very stiff core which snaps when bent too much and is probably the worst possible choice. I then soldered this wire onto a flat steel plate with a small soldering iron which had a loose tip, meaning it didn't put out that much heat for the first half of its use, until I figured things out and tightened it. Regardless of that, soldering a stiff wire onto a relatively smooth flat plate is not for the faint of heart with any soldering iron, and certainly not recommended for anything requiring durability. But it held well enough for my uses.
On the other end of the plate is a paperclip which I bent around the plate and the edge of the bowl.
I connected one end of the wall-wart to the coax cable and the other to one lead of a 12V fan (this one from a Pentium II heatsink assembly). The second lead of the fan went to an alligator clip, the other end of which I clamped on the top of the container. The idea, according to those other sites, is to limit the current that can run through the circuit so that the power supply doesn't burn out. Here is what I saw after about a minute of running things:
Nothing much exciting is really happening, except the letters instantly changed color and that same color started slowly running down the side of the container into the bottom of the bowl. However, at this point I did realize that I was on the right track and would likely get some results (my biggest fear had been of no reaction at all because I would need fancier chemicals or something).
The water is just salt water. I actually used salt that is meant for tanning hides, but it only has 0.5% of two other chemicals in it, so it is nearly pure salt. I mixed in about 1/2 cup, which seemed to be about the point it started dissolving slowly.
After 8 minutes, it did not look like much etching had been going on, although it may have been enough to stop there. I'll never know, because I wondered what would happen if I removed the fan. I knew the power supply would not burn out, because I have shorted the wires of it on many occasions and it's still ticking along. So I shorted the fan's wires, effectively removing it from the circuit, and immediately bubbles started flying out of the letters and I could tell something was really going on. I pulled it out after a few seconds and saw that it had bubbled the wax quite a bit, but it seemed my fingernail polish layer was holding, so I put it back in for about 30 seconds total. You can see the damage it did to the wax:
Then I excitedly scraped off the wax around the area, and I knew it had worked:
Taking off all the layers required the use of fingernail polish remover. Since this was the hardest layer to get off, I'm guessing it's the one that preserved things during the final stage when the wax was being abused. If I did it again, I probably wouldn't bother adding the wax as a third layer on top of the other layers. (But I would still use it for the rest of the container, as it worked fine there). Here is the result, cleaned up a bit more:
I found the best way to remove the rest of the wax was to scrape it clean with the plastic spoon. Then to get the small bits that were left I ran it under very hot water from the faucet and used a scrub brush. The water wasn't hot enough to outright melt the remnants off, but it made them loose enough to brush off.
I think I could use some sort of coloring compound, maybe shoe polish, to make the letters all one color. However, they look fine to me, and I'm guessing that over time they will get dirty and become one color anyway. If you didn't want that to happen (or wanted to preserve any color you rubbed in there) you could put some sort of clear coat over the top; maybe the same clear fingernail polish.
End result: I'm glad it turned out as well as it did. The edges could be a little sharper, but I'd rather not have any obvious leaks in the mask, and I really didn't. It did take about 5 hours total, so it's not anything quick, but it is a really cool result that I'm happy with.
Notes:
- It might have been easier to remove the paper layer if I had just used a magazine page rather than the cover. This might also have let me heat the toner better.
- I'm no chemist so I can't predict what materials it would work on, but the other sites I mentioned at the top have done something similar to copper plates and also to Altoid tins, whatever kind of metal that is.
- One interesting thing happened while it was in the stove. I was carefully watching it, half expecting the plastic piece to droop and fall off from the heat, when all of a sudden there was a loud bang and the container jumped about 3 inches off of the oven rack. Apparently the air inside expanded enough to pop out the curved back side. This could have been prevented by being smart and loosening the cap a bit. Oops.
- Mistakes in doing the fingernail polish layer are very hard to fix. In fact, nearly impossible. Be ready with something to quickly dab any errors off--I used a toothpick and a napkin.
- I did have a small hole in my wax, on one of the bottom corners. So that spot got etched a tiny bit too.
- I might work to only use wax and carve your design in it, provided you leave the fan in the circuit. The higher current otherwise might damage the was as I observed.
