Etching Aluminium

Has anyone tried doing this?

Lots of varying comment about etching aluminium out there.

The obvious choice of caustic soda is no good as it will destroy the etch resist.

Some sources say use ferric, others say its useless.

One source suggests using ferric exhausted by use on copper - seems a bit dubious?

Neil

Haven't tried it myself but these guys seem to have the know-how: **LINK**

https://www.precisionmicro.com/the-photo-etching-process/?gclid=EAIaIQobChMIzMyfnuyP2QIVirDtCh0nLglyEAAYASABEgKIWfD_BwE

MichaelG.

Chloride ions do quite a good job on aluminium oxide and aluminium is amphoteric. So, both ferric chloride and hydrochloric acid will work if the resist is stable in acid conditions. Don't bother with nitric or sulfuric acid. they'll tend to reinforce the oxide film.

Edited By Mark Rand on 05/02/2018 23:04:33

I suppose it depends on the reason you want to etch it. I assumed it was to create a keyed surface for accepting paint but as you mention resist it doesn't compute.

Ian P

Etching is a process by which you apply an acid to metal, causing uncovered parts to be "eaten away" by the acid to etch a specific design in your metal. You apply that design using a "resist," a substance that covers the areas on metal that you do not want to be etched. The uncovered areas of the metal will etch, leaving behind a raised impression of your design.

Paul

I havent tried any process personally except for basic circuit boards with ferric but you may be able to use electrolytic etching to do what you want , there is a basic explanation on the instructabled website . They use a vinyl mask but it has me thinking something similar could be 3D printed and glued on to the face to be etched to make a mask .

Ian

Wikipedia gives;

For aluminium

• sodium hydroxide
• Keller's reagent

Brian

Hi Brian,
Sodium hydroxide is just the chemical name for caustic soda.

Les..

I want to use photo-resist, which is developed using NaOH and exposing it to the solution for too long destroys it.

Kellers reagent has nitric, hydrochloric and hydrofluoric acids in it - no thanks! It's used for revealing grain structure anyway.

I'll do a trial with ferric as I have plenty in stock.

Washing Soda, or even baking soda would be a good place to start.

Ian S C

Washing soda or baking will attack the resist too - they are weakly alkaline.

Neil

One of my text books suggests Cupric Chloride as a metallurgical etch for ally. A quick Google suggests that people do use it for larger scale etching on ally so this might be a useful lead.

HTH,

Rod

This might be a bit of an aside but an old way of cleaning silver is to put a bit of aluminium foil in a brine (common salt) solution and then put a tarnished bit of silver in. It works, you can smell the hydrogen sulphide from the tarnish being removed. Afterwards the aluminium foil is pin holed, possibly selectively etched by the process. Perhaps an electrolytic process might be worth trying though the pH might change during the etch.

Dick.

It seems the problem is not what will etch aluminium but what the resist will resist. I found to my cost that brick cleaner eats aluminium which I did know but forgot to remove an aluminium nameplate when derusting.

Mike

That fits in with using ferric that's been exhausted etching circuit boards.

Look here Folks:

http://www.instructables.com/id/Create-custom-etched-aluminium-aluminum-art/

He says Lemon juice might work as well.

Regards

Johannes

I was once asked to write on aluminium light bulb caps using chromic acid and a stick. At the time I thought that was etching, but it seems it produces a 'corrosion resistant' oxide layer. It might work as a resist.

Alan, you are right about the chromic acid, that's what we used in the aircraft industry to neutralize corrosion on aircraft skins{Alclad), then they got a coat of zinc chromate primer

Ian S C

Hi Neil What are you trying to etch into the aluminium? the last time I had something done I had it laser etched and it didn't cost a fortune.

David