Etching faceplates, was RE: [sdiy] Plexiglass panels

[Robert Kent]

On Tue, 12 Jul 2005, xamboldt wrote:
> Hey Robert,
> These look fantastic. I'm particularly interested in the galvanic etching.
> Would this would on anodized aluminum? If so, it might look quite nice if
> the process ate the anodization and a bit of the aluminum below and left the
> bare aluminum showing your markings...

Hello, Chris!

Thanks for the kind words. I'm afraid etching anodized aluminum is 
probably impossible, since the anodized finish is a non-conductive layer 
of aluminum oxide and the galvanic etching process requires conductivity 
to work. Of course any scratch or other break in the finish would allow 
the underlying metal to be etched with a much deeper relief image.

I haven't explored home anodization, but I wonder if the metal could be
masked from the process as with etch-resist.

--Robert


> On 7/8/05 3:38 PM, "Robert Kent" <hanuman at ccsi.com> wrote:
>> Galvanic etching is done by suspending the workpiece in an electrolyte,
>> along with a waste piece of the same material. A salt of the metal being
>> etched is supposed to be the most effective electrolyte, but I used
>> a few tablespoons of ordinary table salt dissolved in warm water. The
>> workpiece (anode) is connected to the positive side of a low-voltage,
>> high-current power supply (I used 13.8VDC at 5-10A, a car battery would
>> work as well). The waste sheet (cathode) is connected to the negative side
>> and current is applied. After 15 minutes or so the bare areas of the anode
>> are etched into sharp relief. I used toner-transfer etch resist which
>> didn't transfer to the aluminum very well, requiring some touch-up with a
>> paint pen, but held up pretty well in the bath.
>>
>> Below are the anode and cathode ready to etch:
>>
>> http://www.ccsi.com/~hanuman/bass-preetch.jpg
>>
>> And the results after cleaning, filling in the relief design with enamel,
>> brushing, and assembling the module:
>>
>> http://www.ccsi.com/~hanuman/bass.jpg
>>
>> Although moderately work-intensive, I am very happy with this process. The
>> resulting front panel markings will never fade or wear away in the normal
>> course of operation, and will probably outlast me.
>>
>> Here's a site I found very helpful in explaining the chemistry and
>> practice of galvanic etching:
>>
>> http://greenart.info/galvetch/
>>
>> --Robert