The authoritative public forum
  for Metal Finishing since 1989
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WHY do nails rust?

Well you have so much information you decided to make a website about it (rusting), well, I've been looking all over, every search site I could find, and nothing told me why nails rust. I mean I know because air and water, but what exactly is the chemical stuff? If you could tell me, that would be great.

Thanks,

Donna T. [last name deleted for privacy by Editor]
Wendler Middle School - Anchorage, Alaska
2003

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Rust is iron oxide, a compound built iron from the nail and oxygen from the air. Things rust because rust is a more stable, lower energy, form for the materials than the separated state. When an iron atom encounters an oxygen atom they can release energy by combining with each other. For the iron oxide rust to re-separate into iron and oxygen would require the addition of energy. Think of a coin balanced on its edge as being the manufactured iron nail. If you tip it over it's going to just lie there, not get back up on its edge by itself, and rust will not separate back into iron and oxygen by itself.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

What colors on a nail identify the steps of rusting on a nail?

Cydney R [last name deleted for privacy by Editor]
student - Ft. Richardson, Alaska
2006

Well, the colors usually are orange, orange red, red then after awhile it turns almost black

Antonio J. [last name deleted for privacy by Editor]
- South Carolina
November 5, 2008

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November 9, 2008

It depends on what kind of nails your using. Copper would turn a very light green but other metals such as aluminum would just turn a reddish-brown right away in little spots on the metal.

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MaPlEsToRy

Maplestory Rox
- Atlanta, Georgia

Does rust differ the weight of the original object?

Pat Hiscock
- Palm Beach, Florida, USA
February 28, 2011

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Hi, Pat.

Yes. Iron from the object combines with oxygen from the air to make rust, and iron plus oxygen will weigh more than iron.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 28, 2011