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Author Topic: Tidying up salt water etching.  (Read 176 times)

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Offline SirRawThunderMan

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Tidying up salt water etching.
« on: September 11, 2019, 12:01:14 PM »
Hey folks.

So, I'm something like a week off finishing my current build. Chassis is complete, electronics done, metalwork 70%. This one will feature some fairly deep etching in a few places. I've been doing test etches for a few days now, I've refined my technique to the point where I can reliably get my etches to about 0.4mm deep with little to no under etching. I'm at the point where I'm ready to etch actual MHS pieces.

The only thing I'm not 100% happy with is the etched area itself, both from a visual and tactile point. Visually, that raw etched alum look is a little unappealing, which tactily, the etched aluminium feels somewhat... odd, to my fingers. Is there any way to clean it up? I know painting over the area is viable, but I was wondering if there was anything like an abrasive slurry or paste that could be scraped around the etched metal to smooth it over a bit.

Any thoughts?
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Offline Darth Chasm

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Re: Tidying up salt water etching.
« Reply #1 on: September 12, 2019, 05:15:40 AM »
I've used sand paper on areas it would fit. Some etching is pretty fine detail so that may not work in all cases. I think you can find aluminum polish in varying coarse. It may not be cheap though.

Offline Greenie

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Re: Tidying up salt water etching.
« Reply #2 on: September 12, 2019, 02:45:02 PM »
Ive found that wire wool works well to remove the black residue of the etching. You can take it back to a 'brushed' metal finish, should you wish to.

Offline SirRawThunderMan

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Re: Tidying up salt water etching.
« Reply #3 on: September 13, 2019, 08:40:13 AM »
I spent some time re-watching Clickspring's videos on YouTube, because I could have sworn he had something for polishing small nooks and crannies that I could use. from that, I got recommended oilstone powder paste as a coarse abrasive, followed by diamantine powder paste. Both of which are way too expensive for my needs.

So, I decided to re-work the etching to make the etched areas smaller and finer. I can just about get away with 0.5mm wide cuts on the vinyl cutter I'll be using to cut the etching resists from, so with any luck, that should work.
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Offline jbkuma

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Re: Tidying up salt water etching.
« Reply #4 on: September 13, 2019, 10:15:37 AM »
If the problem is that it looks rough, you might want to try using a weaker solution or lower power.  Ideally, it will come out pretty smooth.

Offline Onli-Won Kanomi

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Re: Tidying up salt water etching.
« Reply #5 on: September 13, 2019, 05:51:31 PM »
Maybe jewellers rouge might work?
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Offline SirRawThunderMan

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Re: Tidying up salt water etching.
« Reply #6 on: September 15, 2019, 03:08:45 AM »
For anyone who might be interested, I think I might have found something that works. I had to make a small lye solution to strip some average anodising off a not-saber project. On a whim, I decided to dunk one of my deep etching test pieces in it for about 30-45 seconds, and then scrub the etched area with an old toothbrush. And that worked surprisingly well. It smoothed over the rougher spots quite nicely, without damaging the non-etched areas. Here's a before and after:


Before had a rough feel to it, almost like 120 grit sandpaper. Not nice to touch, definitely on the ugly side. After is still a bit on the rough side, but the feel is closer to 800 grit sandpaper. Much smoother.

I used a mix of 250ml tap water, 50g sodium hydroxide (aka lye, caustic soda, drain unclogger pellets.) Test pieces dunked for 30-45 seconds, then rinsed under running water for 30 seconds, followed by scrubbing with an old toothbrush. Repeat three of four times.
I used to be a Jedi like you, then I took a lightsaber to the knee