How to Make Aluminum Corrode / Patina?
A discussion started in 2006 & continuing through 2017
Q. I have a client who wants a pitted finish on a sheet of 16 gauge aluminum. I know aluminum does not rust, but that doesn't mean it won't corrode, how it corrodes though is where I have no idea.
Is there anyway possible to get a finish like this? Is a week enough time for a pitted finish?
I looked over some articles on this site and have found that alkaline and aluminum are not friends. Would soaking the plate in a rich alkaline heated environment be the answer?
I think/believe he is going for a simulated rust, pitted feeling of steel, without all the iron dust, weight, and so on.
The piece is not going to be used for anything structurally speaking; he is a graphic designer so it is something along the lines of that use.
Fabricator - San Jose, California, USA
A. Hi John. Bare aluminum can corrode quite readily, but the problem is that the corrosion products will not look like what he is envisioning. Corroded aluminum is not brown with a fine grain, like rust on tool steel. Rather, the corrosion products are white, random pitted, crusty volcanos, and somewhat like salt stains. If you have a sliding shower door more than a couple of years old, look at the corner joints -- the extrusions are anodized, but cut to length after anodizing which exposes bare aluminum (at least if you have cheap ones like I do). I'd suggest a decorative rust-like paint or iron paint if you want rust color. Good luck.
Ted Mooney, P.E.
Pine Beach, New Jersey
Q. Ted, thanks for the reply.
"Rather, the corrosion products are white, random pitted, crusty volcanos, and somewhat like salt stains."
I told him that the corrosion produces a white salty-like finish. He loves the look. I had 15 year aluminum frame I showed him and he loved the look.
Is there any way to rapidly speed up the corrosion of aluminum to make the piece look like it has been sitting for 15 years like my frame?
Thanks in advance!
You guys have a great website here!
- San Jose, California, USA
A. Try glass bead blasting.Ken Vlach
- Goleta, California
amadeya42.com honored Ken for his countless carefully
researched responses. He passed away May 14, 2015.
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A. Any very alkaline solution (pH8,5 or more) must etch or corrode aluminum. Try sodium carbonate 10% (or even sodium hydroxide 2-5%) -- mix it with some sawdust or sand,c over your object with this mix, after a few days it must be ok. Good luck!Goran Budija
- Zagreb, Croatia
A. Try a mixture of 5% sodium hydroxide with about 5g/l sodium chloride in it (common salt). Mix this with some sawdust and leave it for a few days on the aluminium surface - it will give a corroded finish. If it is not corroded enough, put the sawdust back for a few more days or until it is the finish you need. Make sure you keep the mixture moist.
R&D practical scientist
Chesham, Bucks, UK
A. If you put bleach and salt onto the aluminum, especially a gel bleach so that it sticks (I used toilet bowl cleaner) then cover with plastic you will get a pretty good patina in an hour.Julie Anderson
- Boise, Idaho, USA
Hi Julie. Thanks for the posting and illustration. Only trouble is, your example isn't aluminum :-)
It looks like a tomato juice can or pineapple juice can made of steel with a tin coating. We can see the brown (iron) rust on the lid seam.
Ted Mooney, P.E.
Pine Beach, New Jersey
November 17, 2016
A. Ferric Chloride (etching fluid) and apply heat.Ben Brickwood
Sesame Design - Kingston England
November 5, 2017
Q. How could I make disposable aluminum pie plates look red/rusty? It seems like there's some discrepancy (above) about the color of corroded aluminum...so are you saying there is a spray or paint application that could achieve that look better than actual corrosion? Thank you!April Heimerle
- Nashville, Tennessee USA
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