Electro etching enclosures

[marcelomd]

Hi,

TL;DR: Does anybody has experience with electroetching enclosures? I'm thinking about giving a shot and would like to hear the good, the bad and the ugly before investing in the expensive stencils.

Ok. I was thinking about finishing my enclosures and not having to deal with paints, acids, or anything that needed safety equipment. Something I could do on my kitchen. So, one of these days I was hanging out with my father. He has a cutlery business and sometimes he marks the blades for his customers. Logos, names, initials, etc.

His setup is similar to this:

It works very well on stainless steel, so we tried it on aluminum. The result was crisp, but the mark was white and hard to see. Looks like different metals have different electrolyte and current requirements. We were using some proprietary secret formula with an AC only power supply (12VAC).

The next day I made a highly sophisticated etcher, using a 9VDC pedal power supply, with two copper wires and a piece of cotton. The electolyte was vinegar and salt, in precisely unknown proportions. The result was so good, crisp and dark, that I forgot to take pictures.

The next step is a proper power supply, with DC and AC options. This I can do in one weekend. I also need the stencils, which are more or less expensive (about the price of a Boss pedal for an A4).

Thanks!

[Marcos - Munky]

I didn't gave this method a try yet. I'm curious to see your results.

The good is, as you said, you don't have to deal with acids (I wouldn't say ferric need safety equipment, I never used any equipment. but it surely needs to be careful because it stains everything). The bad is you have lower detail level than other finishings. Can't think of any ugly, probably the stencil price.

[duck_arse]

if you use AC, one half-cycle will take metal away, and the next half-cycle will put it back. this might be why you get white with the AC, it's putting back bad stuff. the DC will take it away and keep it gone.

[EBK]

My first etch was the accidental result of an electroplating attempt.  Does that count? 
(Answer: no. My solution was just too corrosive for the zinc enclosure I was trying to plate.)

[marcelomd]

Hi,

So I finally got to run some experiments with etching. The results were mixed as you can see in the photos below.

This is the setup. The box is from a local manufacturer. It outputs 12VAC, so just a transformer. On top of it is a 9VDC power supply with some wires. I don't really know how close the stencil for marking/etching is to the ones used with paint.


Yes. My father's clients ask for comic sans a lot.

This is the blue mystery liquid supplied with the marker machine. There is no info on the composition, but I guess it is copper sulfate + water.


I ran the experiment on the back cover of a chinese hammond knock off and on a stainles steel spatula. I forgot to take pictures before starting. Both materials had similar results. Every etch was performed by sweeping the marker head for =-20 seconds over the stencil.

A - 12VAC + Copper sulfate
B - 9VDC + Copper sulfate
D - 12VAC + vinegar + salt
E - 9VDC + vinegar + salt
F - 9VDC followed by 12VAC +  copper sulfate. I messed the alignment while changing power supplies.

Results:
Aluminum (the blue/green tint is from my wall):




Stainless:


Both materials:


Some thoughts:
I expected Aluminum and stainless steel to react a bit different. The results were almost the same.

AC vs DC: As Duck said, DC takes metal away, while AC makes it change colors. I am more interested in labeling, so I did not try to see how deep it could go, etching for only 20 seconds. You could clearly feel the etch with your fingers.

Copper sulfate vs vinergar+salt: Copper sulfate gave a crisper mark, with a slight brown tint. Vinegar had a blurry aspect to it, as if etching under the stencil. My guess is that this solution was more conductive, so it "pulled" metal from a larger area.
I did not take pictures, but I tried with a brown liquid (I guess iron chloride + water). It did almost nothing to aluminum but yielded such a crisp, black, mark with the stainless steel. Almost like printing.

The AC only marks are very superficial and can be scrubbed away with the coarse side of a sponge. I guess that is why knife makers do a deep etch with DC and then highlight it with AC.

Last time I tried it, I got very white marks with AC+copper in aluminum. This time, it was the best result for me (letter A), so I'm gonna stick to it for labeling. All letters, except A had this effect that they changed from black to white depending on light and orientation. If I were going for a deep etch + painting and sanding, I would use vinegar, to get that cool pitted effect.