Why is rust photography so interesting to me? Well, I grew up with a mill and creek literally in my back yard and a father who was an engineer with an amazing workshop and garage. My dad could whip up just about anything and I was never the girl who played with dolls or dressed up. No, I was always dirty and you could either find me in the garage under the car handing my dad his tools, or on my bike in a neighborhood that was home to many mill workers. I would often see giant pieces of metal going in and out of the mill or sitting around in the lots nearby. As a kid who loved to explore, I found myself in places where kids probably shouldn’t be, back then rules weren’t what they are today. The mill is a leading producer of forged and cast rolls for the worldwide steel and metal industries, so you can see why I may have a bit of interest in rust photography Pittsburgh Art!
Yellow Rust
Iron oxide-hydroxide FeO(OH)H2O (high moisture)
Rust from Iron (III) oxides that is a very soluble iron oxide results in yellow rust.
- Yellow rust is distinguishable in recessed areas of the metal parts/equipment where the rust “runs and drips” (solvated rust).
- Yellow rust forms as a result of very high moisture content. It frequently found in settings where puddled/standing water has most likely been present.
Red Rust
Red Rust is actually a mixture of four things.
- Iron/Steel
- Water
- Oxygen
- Time
When Iron/Steel is exposed to water and oxygen for a long period of time the iron/steel actually combines with the oxygen on the atomic level. This creates rust or ferric oxide. Once this process has begun it begins to deteriorate the metal itself.
Brown Rust
Oxide Fe2O3 (high oxygen/low moisture)
Rust from Iron (III) oxides with high oxygen and low moisture results in brown rust.
- Brown rust is a drier rust than those mentioned above.
It is most likely atmospheric – having formed as a result of water and oxygen in the atmosphere and presenting as a reddish-brown crust on the metal’s surface. - Brown rust is sometimes localized rust which appears as non-uniform spots or only in certain areas rather than over the whole surface. It can be the result of a contaminate on the metal’s surface often originating from the manufacturing process.
Green Rust
Several chemical processes produce green rust:
- Electrochemically oxidizing iron plates can form a green carbonate rust.
- Green rust may be prepared by bubbling carbon dioxide through a suspension of iron(III) hydroxide Fe(OH)3 in iron(II) chloride FeCl2.
- Green sulfate rust may result from mixing FeCl2·4H2O and NaOH solution to precipitate Fe(OH)2. Sodium sulfate Na2SO4 is added and the mixture is oxidized in air.
White Rust
White rust occurs on the surface of Zinc plating. It appears as a coating of powdery white zinc oxide. This oxidization process will occur just from being exposed to the atmosphere but can be avoided by adding a chrome coating before it has been exposed for a long period of time.
Black Rust
Underneath this reaction hidden by the red is actually another layer of oxidization known as black rust or black oxide. This layer is harder and thicker than red rust and can also be called magnetite. This rust will stay tightly bound to the to the base material and act as a partial protection from a further oxidization process. Note: Not able to create this type of rust as an low oxygen environment is typically needed to induce black oxide.
Related Link for Red, Black and White rust – https://www.albanycountyfasteners.com/blog/2017/09/22/rust-three-types-rust-occur/
Related Link for Yellow and Brown rust – https://www.armorvci.com/corrosion/types-of-rust/
Related Lind for Green rust – https://www.thoughtco.com/green-rust-how-it-works-3976087