This Corrosion

[e_spy]

Spent yesterday over at Making Space in Havant messing with electrochemical etching. I've done a moderate amount of marking of steel, but somehow have never got around to doing any deeper etches (which is daft really, given the kit I've got

Comments

[jarkman]

Very interesting. How big is that piece ?

[e_spy]

That one's about 50x50mm. All the technical concerns about current density and similar went out the window with this approach. Etch time for that was 3 cycles of 4 min each. Booked on the setting course now too- starts 11 May.

[cursingchemist]

A very interesting test piece. I note that you simply used salt water as electrolyte. I found that this electrolyte became rapidly 'muddy' (ferric hydroxide, expected as the solution becomes progessively more alkaline in operation), and found that acidifying it (I first used white vinegar saturated with salt, and later salt water with a generous dash of hydrochloric acid) seemed better. I did not use mesh (or other 'bag') over the cathode, but I stuck it inside a piece of plastic pipe with a large number of small holes drilled in it, which kept the worst of the sludge and annoying bubbles confined, and avoided accidental shorts against the cathode when moving the work around

[e_spy]

Thanks for that - this was a fairly Heath-Robinson approach, which amused me given my inclination to over-think things

[cursingchemist]

>any likelihood of ferric chloride being formed

[e_spy]

I'm not sure I can believe NaOH being formed, that sounds like a lye to me