etching aluminium

This topic has 14 replies, 8 voices, and was last updated 22 January 2017 at 17:27 by duncan webster 1.

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20 January 2017 at 06:42 #278975
Dougie Swan
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@dougieswan43463
Hi

Can anyone tell me if there is a chemical that will etch aluminium like ferric chloride works for brass?

Thanks

Dougie
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20 January 2017 at 06:42 #25023
Dougie Swan
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@dougieswan43463
20 January 2017 at 07:08 #278978
Speedy Builder5
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@speedybuilder5
Caustic soda ?
20 January 2017 at 07:13 #278979
John Haine
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@johnhaine32865
Caustic soda certainly but very aggressive! I believe that sodium carbonate, a/k/a washing soda, works well and will be safer. Milk bottle tops in washing soda was a way to make hydrogen gas at home if you didn't want to use zinc and hydrochloric acid. Note, etching Ali with an alkali gives off inflammable hydrogen so good ventilation and no naked flames indicated.

A bit of searching throws up this link that confirms a pretty vigorous reaction between hot NaCO3 solution and aluminium foil evolving bubbles of hydrogen gas.

https://m.youtube.com/watch?v=ggPWdwcsyqM

Edited By John Haine on 20/01/2017 07:24:43
22 January 2017 at 07:36 #279435
David Cambridge
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@davidcambridge45658
Have you considered electrolysis ? I’ve been meaning to try it with salt and electricity, but I still need to do a bit of research before I try it (just in case it yields anything nasty!)

David
22 January 2017 at 09:43 #279452
John Haine
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@johnhaine32865
No need for electrolysis!

Actually printmakers use aluminium for etching plates as an alternative to zinc, using a mixture of copper sulphate and common salt, which has the advantage that it also etches zinc so you only need one solution. I suspect that it is also much more controllable than sodium carbonate (judging by that video I linked to), which is important when making an etching plate.
22 January 2017 at 09:44 #279454
Neil Wyatt
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@neilwyatt
Posted by David Cambridge on 22/01/2017 07:36:16:

(just in case it yields anything nasty!)

Hydrogen and Oxygen in an exact 2:1 ratio … 'keep away from naked flame'…

Neil
22 January 2017 at 09:53 #279459
Michael Gilligan
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@michaelgilligan61133
Posted by John Haine on 22/01/2017 09:43:00:

No need for electrolysis!

Actually printmakers use aluminium for etching plates as an alternative to zinc, using a mixture of copper sulphate and common salt, which has the advantage that it also etches zinc so you only need one solution. .

.

Thanks for that, John

My day isn't wasted … I've learned something already.

MichaelG.
22 January 2017 at 10:02 #279465
Dougie Swan
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@dougieswan43463
Thanks for the replies

I will have a go with a few tests later

Dougie
22 January 2017 at 10:18 #279469
Neil Wyatt
Moderator
@neilwyatt
If the results are worth reporting on, a short write up for MEW would be useful

Neil
22 January 2017 at 12:01 #279480
David Cambridge
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@davidcambridge45658
'Hydrogen and Oxygen in an exact 2:1 ratio … 'keep away from naked flame'…'

At the risk of being a pedant, it’s hydrogen and chlorine – so keep away from naked flames and naked lungs (if you want to use them afterwards ).

David
22 January 2017 at 12:25 #279484
John Haine
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@johnhaine32865
Using sodium carbonate it just liberates hydrogen, certainly not chlorine. The link I posted earlier was rather general, the one I should have posted is here.

He doesn't mention chlorine as a hazard.
22 January 2017 at 13:09 #279488
vintagengineer
Participant
@vintagengineer
Ferric Chloride will etch aluminium quite nicely. We used to use it for making aluminium flexible pcbs. It will need agitating as the spent etch will sit on the surface and slow down the process.

A warning, keep low grade gold jewellery away from the solution. It used to be quite embarrassing when we had to explain to young ladies that their engagement rings had fallen apart due to very little little gold and lots of copper in the rings!

Edited By vintagengineer on 22/01/2017 13:16:45
22 January 2017 at 14:20 #279497
Neil Wyatt
Moderator
@neilwyatt
Posted by David Cambridge on 22/01/2017 12:01:29:

'Hydrogen and Oxygen in an exact 2:1 ratio … 'keep away from naked flame'…'

At the risk of being a pedant, it’s hydrogen and chlorine – so keep away from naked flames and naked lungs (if you want to use them afterwards ).

David

Ah I hadn't noticed the electrolyte had changed from sodium carbonate to salt!

In that case keep away from direct sunlight too..
22 January 2017 at 17:27 #279530
duncan webster 1
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@duncanwebster1
Won't the chlorine dissolve in the water? If so you'll get hypochlorous and hydrochloric acid rather than gaseous chlorine. Still better to stick to carbonate.
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