Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
-----
How to darken or rust aluminum
Quickstart:
The conventional way to color aluminum (omitting painting & powder coating) is to anodize it. That builds a layer of tiny honeycomb-like chambers from the base of the aluminum to the surface, which can be filled with dye and then sealed. We have an Intro to Anodizing where you can read more about that subject.
This thread is about ways to apply a rust finish or rust-like finish without anodizing.
Q. Hi Goran, thanks for the PDF! ⇨
This is all VERY interesting... Am I understanding the charts in the PDF correctly?
On the Aluminum #4., I would mix 20g of Potassium permanganate
⇦ this on
eBay or
Amazon [affil links] with 1 liter of water and heat it to 80-100 °C, then submerse the objects for (not sure how long) and it would give it a golden yellow color?
For Aluminum #3 there would be no heat involved, just mix 1 L water with 5 g of each chemical?
Thanks!
hobbyist - Austin
November 6, 2024
A. Al #4 - immerse objects until color is developed...
Al #3 - according to Handbuch der Galvanozechnik/Munich 1968 [occasionally avail. from
eBay,
AbeBooks, or
Amazon affil links] 70-80 °C. Solution is not stable, you must prepare it fresh every time...
Colors are not stable and attractive like colors on anodized items- you must protect them with wax or clearcoat.
Hope it helps and good luck!
- Cerovski vrh Croatia
November 12, 2024
Understood.
Thanks!
- Austin
November 16, 2024
⇩ Related postings, oldest first ⇩
Tip: Readers often just skip abstract questions;
they want to learn from your actual situation.
Q. What acid or other agent do I put on aluminum to give it a rust appearance?
Thank you,
Retired - Flatonia, Texas., USA
2002
A. Aluminum doesn't rust and can't be made to rust, Walter. I've seen in the home decorating magazines that paint manufacturers are offering rust colored paints, which is probably the simplest approach.
The more authentic approach is probably a rust patina. This is a process with at least two steps: first a metallic surfacer with real iron particles is applied, then the activator is applied which causes those metal particles to rust.
But there are 3-step kits because an acid blocking primer is recommended to precede the metallic surfacer, and there are 4-step kits because the rust finish isn't real wear resistant, so a clear coat is added if the rust finish is to be employed in a wear situation or outdoors.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I need an inexpensive rust look for aluminum sheet also. Preferably in a powder coat or urethane paint.
Roger Capehart
custom metal fabrication - Powder Springs, Georgia
2004
A. Hi Roger.
Rust colored paint and powder coatings are widely available. Some are designed to very closely resemble Cor-ten weathering steel. But spray cans of rust colored paint are available.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I am trying to age aluminum. Don't want the white powdery look. Just want to darken it. My husband is building a miniature toy race car and wants it to look older. I will appreciate any help.
Irene MartinNostalgic Americana - Hudson, Florida, USA
2005
|
A. A thin layer of colored resin will give it an antiqued look. I think. Marc Banks- Elizabeth City, North Carolina A. You can oil it very sparingly (olive or boiled linseed oil
⇦ this on
eBay
or
Amazon [affil links]
or any other edible oil or fat), then you must heat it to 200-400 °C. - Cerovski vrh Croatia |
? Goran,
I've used this process on bronze before to darken it to a moderate patina, but I've not heard of this being used on aluminum. What sort of colors/finish does this give?
- Elizabeth City, North Carolina
2005
A. Dear Marc!
This process can be used on any metal (if that metal can be heated to 400 °C). According to old books olive oil is best for aluminum. White of an egg is usable, too. With linseed oil I have coloured a piece of aluminum to bronze brown (bad smelling and tedious!). You can use 20% shellac solution instead of oil.
Good luck!
- Cerovski vrh Croatia
2005
Q. Sorry, I'm afraid I am a lowly consumer, but I thought I'd take a chance that you might help me out. I want to use corrugated sheets of metal (I guess it is aluminium) from "Home Depot" for a ceiling in part of my house. But, I want it to look "Old" or "Aged" not the shiny bright looking stuff they sell.
Any thoughts as to what I can do to change the look, short of leaving it outside for a year or so?
Thank you for your consideration.
- New York City
2005
A. Hi Dan. When we don't know what kind of metal we have, we can't know what chemical/acid/alkali will react it with to get a particular look -- it's a bit like finding a bag of white powder in the basement and trying to figure out what to add to it to make a cake). Instead, I'd suggest priming it with a primer made for aluminum and galvanized metal ⇨
then using a kit (like described above) with a metallic surfacer and patina solution designed to rust the metal contained in that metallic surfacer.
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Is there a risk of warping thin aluminum material during the heating process? Specifically, I have an antique rifle that was modified with a thin aluminum cap on the nose of the forearm. The fit is nice but the polished look does not conform to the period, would like to darken it. Thanks for the info.
Ken
- Bemidji, Minnesota, USA
September 28, 2009
A. Hi Kenneth. It's hard to fully understand this component from the description, but if that cap is now a permanent part of the rifle, I certainly wouldn't heat a whole antique rifle. Pick a brush-on patina of some sort; if adhesion seems problematical, prime it with a primer for aluminum and galvanized metal first ⇦ this on eBay or Amazon [affil links] .
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Creating 'antique zinc' patina on raw aluminum
Q. Hi. I hope everyone is staying safe and healthy. This is my first post so thanks in advance for any guidance.
I have a custom metal planter and furniture design and fabrication business. I work mostly with cor-ten / weathering steel and 5052 aluminum sheet.
I'm working on developing an 'antique zinc' look for my aluminum planters but don't have a good solution yet. I know I can get the aluminum a dark gray / black and that is cool but I'd also like to find a way to get a lighter grey finish.
- Ocean Ridge Florida
October 24, 2020
Ed. note: So how do you "get the aluminum a dark gray / black"?
No quiero nada por nada, No te lo quiero tomar, Qué por entendido tengo, Qué él que toma-tiene que dar.
Q. Hi all,
I'm trying to form a dark patina on my Wilton Armetale dinnerware pieces but would like something more predicable than running them through the dishwasher over and over again. Their website says they're made of an 'aluminum alloy' and they can withstand extreme oven temperatures. Any suggestions are appreciated.
Thanks!
- Grand Junction [Colorado?]
September 10, 2021
Wilton Armetale dinnerware on eBay (affil link)
A. Hi M.
Goran offered a solution that sounded like a bullseye to me. Please try it and let us know how it works.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Sure thing, Ted! I wasn't sure if that method would work on an alloy like that of Wilton. I'll try olive oil and get back to this thread.
- Grand Junction, Colorado
Hi Ted,
So I tried Goran's recipe of olive oil on the aluminum and it certainly worked to change the patina -- but it turned it from gray to a shiny brass; not exactly what I was looking for. Reading Goran's thread more carefully, this makes total sense in the context of creating a brass/bronze patina. The question of how to only darken the aluminum patina however still stands. Also do so, if possible, without the use potentially harmful chemical agents, as the Wilton pieces are meant for food.
I recently started collecting vintage Wilton Armetale dinnerware. Their website says the metal they use in their products is an 'aluminum-based alloy' and to never put it in the dishwasher as that will darken the patina significantly. I however want this darker, more pewter-like patina on my pieces. So far, I've run them on the pots/pans cycle of my washer, using cascade liquid dishwashing soap, but the patina isn't as consistently dark as I've seen elsewhere. Since the pieces aren't exactly aluminum, but some unknown (trade-secret) alloy, what would work best for this; keeping in mind that they still need to be food safe when I'm done?
Thanks!
- Grand Junction, Colorado
September 12, 2021
A. There is chapter on chemical coloring of aluminum (no need for anodizing) in my small download free booklet on metals coloring and plating ⇨
Hope it helps and good luck!
- Cerovski vrh 157 Croatia
September 14, 2021
Wow! Thank you so much for this, Goran. This is the most promising lead so far for me; I’ll be sure to take a look.
- Grand Junction, Colorado
September 15, 2021
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