etching aluminium

Hi

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

Thanks

Dougie

Caustic soda ?

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

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

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.

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

Neil

.

Thanks for that, John

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

MichaelG.

Thanks for the replies

I will have a go with a few tests later

Dougie

If the results are worth reporting on, a short write up for MEW would be useful

Neil

'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

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.

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

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

In that case keep away from direct sunlight too..

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.