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  for Metal Finishing since 1989
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Corrosion of aluminium

2007

Hi I am a student studying jewellery and object design in Australia. I am trying to get an effect similar to a highly corroded aluminium in a marine environment, so lots of soft powdery white corrosion on the surface of the aluminium. I want to do it quite quickly though ˜ over several hours or at most days rather than months or years. It is for a sculpture so it won't be handled or worn, so it doesn't have to be too tough or hard wearing.
All the sites I have been able to find talk about preventing corrosion, not encouraging it - as you would expect I guess.
I have access to fume cupboards and a variety of chemicals etc at college so I can work quite safely - although I do have to provide MSDSs for all chemicals and procedures I use.

Richard May
Jewellery student - Sydney, NSW, Australia

You can mix some sand ( or earth or sawdust)with strong sodium carbonate ⇦this on eBay or Amazon] solution-you must cover your object with this mixture-after some time (10 days or more?)take it out -I think that must work(sand must be wet all time!).Hope it helps and good luck!

Goran Budija
- Zagreb,Croatia
2007

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Interesting question,

You shouldn't need to bother with any nasty chemicals, you can get a very fast reaction with simple saltwater and a galvanic couple.

First...make sure the aluminum surface you're oxidizing is very clean...you may have to use a strong alkaline cleaner to get any passivate coatings off.

It will be easier to rust a small piece of aluminum. Submerge the piece in salt water (use the ocean or make your own) and bring the aluminum into contact with a larger piece of cathodic metal. If you can find it, platinum would work best...but copper, silver, or 300 series stainless would likely make the rusting go fast. The aluminum would act as a anode and would rust very fast.

If you can't find any of the materials above...you can use a regular piece of steel but it might not rust fast enough for your purposes.

Jeff Holbrook
- Louisville, KY
2007

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2007

Thank you for both of those responses, I shall try both tomorrow and see how they go.

I don't have access to platinum, but I can do silver (925), copper or stainless.
Regards,

Richard May
- Sydney, NSW, Australia

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2007

Thanks Jeff, your system worked extremely well and very quickly.
I had a saturated saline solution in a flat tray with my alumuinium bound with copper wire to a copper plate.
Both had been dipped in the saline solution so both were wet, but the copper plate remained in the solution while the aluminium was just out of the solution. I had a good crusting of salty corrosion within about 3 hours, that was well bonded to the aluminium.
I'm sure that it will get better and thicker over several days.

I hadn't had much reaction to the soda ash (sodium carbonate?) solution on Friday, it has been sitting over the weekend, so I will report back on Tuesday evening if any action has taken place
Regards
Richard May

Richard May
- Sydney, NSW, Australia