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

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

Wikipedia gives;

For aluminium

• sodium hydroxide
• Keller's reagent

Brian

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

Ian S C

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

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

Look here Folks:

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

He says Lemon juice might work as well.

Regards

Johannes

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

Neil

As Rod says Cupric Chloride might be worth a try. I switched to using it for etching circuit boards many years ago as it has many advantages over Ferric Chloride (lasts forever as it is easily regenerated after use,amongst others) , and I can testify that it does etch aluminum as I have a heater mounted on an old ali electronic chassis that I use to heat the etchant and it has numerous well etched spots on it from spills.

It can be easily made by dissolving 200gms CuCl2 in100gms conc. HCl (37.5 %) and diluting to 1 litre. The Cupric Chloride is readily available from pottery suppliers as a glaze material, and I use Muriatic acid (readily available at a builders supply) adjusting the quantity as it is normally only supplied as 20 baume which has a density of 1.16 as apposed to the conc. which is 1.18. If maintained at a density of 1.17 g/mL and a acid concentration of 3.5 to 4.0 % or 1.1 to 1.3 Molar it lasts for ever and just keeps increasing in volume.

John

I’ve had stuff Anodised professionally on a few occasions and as I didn’t want a shiny finish they said they’d etch it with Sodium Hydroxide. I’ve always thought sand blasting was a good start for painting aluminium and this was confirmed in a YouTube video I watched some time ago.