In February of last year Eric_R over on reddit was featured for solving the problem of How do you etch something you can't move?
I thought his design inspired and his results are excellent. I told myself if I got a stencil cutter this could be a great way to make masks for chemical etching, electro-etching, maybe even bead blasting. Well, I got a Cameo 3 vinyl cutter recently so it looks like I get to try that out now. Here's a short writeup on how it went.
So to start we need a stencil design, a DC power supply, some clamps, some cotton balls and the advanced chemical formula: vinegar with a big pinch of salt. That's it. Oh, no we also need a stove with poor quality markings that have flaked off. Here's one now:
This is my mothers nice Wolf propane oven. She got it used, it's commercial build quality, yet the same cheap awful front printing as every other cheap stainless stove top. What is that black stuff anyway, laser printer toner? Anyway, it took naught but light brushing with a scotch bright pad to clean the remains off and end up with the stove here. I cleaned everything up with acetone so the vinyl would stick well and nothing would impede the etching.
So next I whipped up some stencil designs in Inkscape, then printed that out on regular paper just to test fit and make sure everything was visible with the knobs on. Those files are linked at the bottom. Then it gets cut out on the Cameo vinyl cutter. I made the stencils extend far enough down that I could use the control knob holes to line everything up. Some electrical tape works as extra masking to make sure nothing gets etched outside the stencils by accident.
Check your polarity!
When hooking up the 12v power supply, the object being etched is positive and the cotton-ball-in-alligator-clip is negative. Don't do what I did on the test piece, which is get them backwards and sit there for nearly 10 minutes wondering why nothing worked. Well something did work, the cotton ball soaked with salty vinegar just etched some tin off the alligator clip. The stainless piece was unaffected.
Now we etch
So with a cotton ball in the alligator clip it gets dipped in the vinegar, power supply set at 12 volts, the etching can begin. I kept paper towel handy to soak up any drips that run down the front: with the electric current present it's possible some errant streams of liquid could lightly etch in even without being directly under the cotton ball. Enough to look like a permanent hard water stain anyway.
I wondered if I'd need some sort of current limiting power supply to keep things going smoothly. I also wondered if a bigger power supply would help this go faster. Turns out things are still high enough resistance that the current was very low, hardly over a 1/2 amp. As I slid the cotton ball up and down over the curved, tapered sections I could actually watch the current swing up and down as the surface area under the cotton ball changed. Like a terrible, terrible rheostat.
One key I discovered while testing on scraps was that you should always keep the cotton ball moving, even over tiny features. Holding it in one place sometimes resulted in bubbles and the area got blotchy. Keep it moving and re-wet the cotton frequently. From this point it was just loosely keeping track of how long I etched over an area so it would turn out somewhat even.
A couple shots of the final result. The glare in the room made it hard to get a good picture of the whole thing. Some more time might have made them stand out a little better, but the markings do stand out well in person. Hardly any material is removed in this process; you can barely even feel the etched areas with your hand.
Just in case anyone wants to try this themselves, here's the vector graphics(.svg) file I used to make my stencils. Stove_etch_template