Electro Etching

Some people have asked about the process I use to etch the Square K logo onto the knives. So here it is. I did a lot of research and looked into a lot of different commercial etchers, which run hundreds of dollars. But the concept is pretty simple and I found some schematics and parts lists on line and was able to make my own etching machine for around $60.

It starts with a knife with a polished, finished surface. This is the batch of K2s I’m currently working on. The handle will be worked on later, but the blades themselves are done.

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I bought a Silhouette Portrait vinyl cutter for around $100. With this, I designed and cut out the logo on an adhesive vinyl sheet. I can pop out the four shapes, leaving holes that will be etched into the metal. These stickers are one-time use but I can print up a batch of 20 in about three minutes, so no big deal.

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The other method of creating stencils is a photographic method. You print out your design on a clear sheet and this is put on top of a photosensitive material which is then exposed to light, creating a stencil. Using the photographic method, you can get much more detailed designs than you can with the cut vinyl, but with my logo being so simple, the vinyl works fine.

The stickers are then placed on the knife and pressed firmly in place. The surrounding area is also masked off to prevent any stray etching.

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This is the etcher I made. All parts from Radio Shack. It’s basically a 120 volt transformer that steps down to 24 volts. But it has a center tap so you can get either 12 or 24. I originally had it at 12 volts, then tried 24 and found that this tended to burn up the stickers a bit, so I put it back to 12 volts. There’s also a switchable bridge rectifier circuit to turn the AC into DC. That’s what that switch on the right is for – to choose AC or DC. DC etches, AC blackens the metal.

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The knife is hooked directly to the positive terminal. The etcher to the negative. The etcher is simply a small piece of brass hot glued to a wooden handle. A piece of cloth is wrapped over it and soaked with electrolyte specifically formulated for etching high carbon steel. There are various formulas you can use, as simple as salt water. I can’t say 100% that I’m getting better results with this electrolyte than I was with the salt water, but it works fine and I have it, so I use it.

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When all is set, you power it up, set the switch to etch, which gives you DC voltage, and press the etcher onto the sticker. The electricity sucks the metal right off the blade and deposits it into the cloth and onto the brass plate.

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I hold it on there for about 10 seconds, then release and repeat about 15 times. Here’s what it looks like after that.

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Then I switch it to “black”. This applies AC current, which results in carbon being deposited on the metal. I do about four 10-second shots of this.

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Take the sticker off and clean it up a bit, and there you go.

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Whole batch done in about fifteen minutes.

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The process actually etches into the surface of the metal. Not deep, but enough so you’d have a hard time sanding it out. The blackening process, however, is just carbon on the surface of the blade. It looks beautifully black at first, but will rub off pretty easily. Still, a good amount of carbon will lodge in the corners of the etch, giving it a nice distressed look. And I’m sure with time, a nice patina will form in the etched area, more than on the polished blade, giving good contrast.

Anyway, that’s the process.

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