What is Rust?

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  • Originally Written By: Michael Pollick
  • Revised By: A. Joseph
  • Edited By: L. S. Wynn
  • Last Modified Date: 05 February 2020
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Rust is another name for iron oxide, which occurs when iron or an alloy that contains iron, like steel, is exposed to oxygen and moisture for a long period of time. Over time, the oxygen combines with the metal at an atomic level, forming a new compound called an oxide and weakening the bonds of the metal itself. Although some people refer to rust generally as "oxidation," that term is much more general; although rust forms when iron undergoes oxidation, not all oxidation forms rust. Only iron or alloys that contain iron can rust, but other metals can corrode in similar ways.

The main catalyst for the rusting process is water. Iron or steel structures might appear to be solid, but water molecules can penetrate the microscopic pits and cracks in any exposed metal. The hydrogen atoms present in water molecules can combine with other elements to form acids, which will eventually cause more metal to be exposed.

If sodium is present, as is the case with saltwater, the corrosion is likely to occur more quickly. Meanwhile, the oxygen atoms combine with metallic atoms to form the destructive oxide compound. As the atoms combine, they weaken the metal, making the structure brittle and crumbly.


Some pieces of iron or steel are thick enough to maintain their integrity even if iron oxide forms on the surface. The thinner the metal, the better the chance that rusting will occur. Placing a steel wool pad in water and exposing it to air will cause rusting to begin almost immediately because the steel filaments are so thin. Eventually, the individual iron bonds will be destroyed, and the entire pad will disintegrate.

Rust formation cannot be stopped easily, but metals can be treated to resist the most damaging effects. Some are protected by water-resistant paints, preventative coatings or other chemical barriers, such as oil. It also is possible for one to reduce the chances of rust forming by using a dehumidifier or desiccant to help remove moisture from the air, but this usually is effective only in relatively small areas.

Steel is often galvanized to prevent iron oxide from forming; this process usually involves a very thin layer of zinc being applied to the surface. Another process, called plating, can be used to add a layer of zinc, tin or chrome to the metal. Cathodic protection involves using an electrical charge to suppress or prevent the chemical reaction that causes rust from occurring.


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Discuss this Article

Post 226

Does it affect water pipe lines?

Post 225

Rust occurs when iron water and oxygen mix together. It's normally called oxidation. Rust is a chemical reaction.

Post 221

I know what rust is but why does it form? Can metals that are not alloys of iron rust?

Post 217

I find it so interesting that people usually fight rust wherever it appears, but many others find the texture so appealing. I see rust textures in advertisements, games and movies regularly.

Post 216

What are human impacts on rust?

Post 212

How do you measure rust?

Post 204

What is the best way to measure rust?

Post 198

Do you have to have oxygen for something to rust?

Post 197

There seem to be a lot of questions on how to prevent rust, but how would you speed up rusting without salt water, and what's all this about vinegar?

Post 196

How is rust so damaging?

Post 191

Why does rust have that red color though?

Post 190

What happens when you take a mixture of bleach, salt and water, put aluminum in it and cover it with a thin layer of vegetable oil? Will it corrode, and if so, will it corrode faster in mild temperatures, cool or under a lamp that is 40 watts?

Post 188

I recently did a science fair project on rusting. I am in year 9. I used water spray, salt water, tap water and white vinegar (mixed with water). I used three iron strips in each. They were all submerged completely except for the spray of course. In the end vinegar rusted the most. It formed a lot of rust and it lost the most weight too. Tap water was next then salt water.

From the research I've done, vinegar removes rust, and salt water is supposed to rust a lot. I am supposed to explain why what happened happened. I can't find anything, though. Can anyone help me? It's urgent.

Post 187

I'm sorry, but I can't find the author of this page! I need it for my bibliography! please help!

Moderator's reply: Thank you for visiting wiseGEEK. You’ll find the author's name to the left of the article, under "article details."

Post 186

what will be the effect if a baby puts a rusty object on his mouth?

Post 184

How would I cite this?

Moderator's reply: Thank you for visiting wiseGEEK. We post all of the applicable information we can provide on each article page -- that doesn’t include the published date or sources. Generally, the accessed date works for bibliographies calling for a date. You’ll find the author's name to the left of the article, under "article details."

Check out the related question in our FAQ for more information about citing to wiseGEEK articles:

Post 181

Thank you guys so much! This helped so much with my science fair project! Thanks. This was very useful.

Post 180

Does the density of a liquid affect the speed of rusting a metal?

Post 179

I'm doing a project on the speed of rust in different liquids such as coke. Can anyone provide any help?

Post 178

Only iron oxide is rust. Other metals undergo oxidation to form oxides, but the resulting material is an iron oxide, not rust.

Post 177

Does the presence of rust on a surface make that surface more prone to oxidation? Let's say, if a metal box was left to the elements and produced some rust, if you took said box, cleaned it and kept it isolated from the elements (a.k.a. outside), would that box be more prone to oxidation in the future?

Post 176

So many questions on here with no or bad answers.

Will soda (coke) oxidize (rust) metal? Yes. All sodas contain phosphoric acid. This is where the bubbles come from, this also decreases the pH of the soda and speeds up the rusting process. P.S. To the doctor who said co2 does not cause oxidation you are wrong co2 is corrosive.

What gives rust its orange-red color? The element Fe (iron) is what turns rust red.

Does the presence of sodium speed up the rusting process? Yes. Sodium increases the conductivity of water, making it a better electron transfer medium and speeding up the oxidation process.

Any health effects upon exposure to deep well water containing rust due to corrosion in

the pipeline?

Depends on many factors, generally speaking, however, no. However, rust on piping makes an excellent site for harmful organisms to form colonies, and severely rusted pipes tend to have poor seals, allowing a whole host of things to seep into your water. If you have high iron in your water it is generally a good idea to find a way to reduce it either though treatment (which well water often needs anyway) or replacing damaged pipes.

How can rust be prevented with just a simple substance? There are whole fields of science dedicated to this question. Generally speaking, coating iron in any compound that seals off the iron surface from oxygen: e.g., paint, plastic, oil.

What are the positives and negatives of rusting? Well, the negatives part is easy. If the metal rusts away, it can fail, potentially causing great damage or bodily injury. The positive is a bit harder to answer. The short version is rusting is bad. However, not all rust is the same. For example, the Statue of Liberty was originally the color of a freshly minted penny. Over time as the surface copper oxidized, it formed a hard protective layer protecting the rest of the metal surface from exposure to oxygen, and greatly slowing down the "rusting" of one of the world most iconic national treasures.

How does the chemical change take place (from metal+water+oxygen = rust)? I couldn't think of a way to explain this easily but the information is available online.

Why does the metal rust more when the plating is scratched? Often metal is treated to resist rusting, but this treatment is only "skin deep." You create a galvanic cell, dramatically increasing the flow of electrons in a very small area.

Do you think iron would rust slowly, quickly, or at all in distilled water? Very slowly, or depending on what exactly your "iron" is made from, not at all.

“I am doing an experiment trying to find out in what type of water iron would rust the fastest...” The slowest will be distilled water by far. The tap water and salt water could be a toss up depending on where you get your tap water from, and how much salt you put in it. Also make sure you use the distilled water to make your salt water otherwise you will have salty tap water and it will spike your results.

As for removing them from the water, I would say no. However, drawing some of the water off, and pouring it back into your sample jar several times a couple times a day could increase the dissolved oxygen content of your water samples and will increase the rate of oxidation.

How long do you think an experiment like this would take? Depends how much rust are you looking for, the quality of your iron and the properties of your sample water types. Most often, nails are galvanized or treated in some way to resist rusting and may takes weeks or longer to show any real signs of rusting.

Why does water rust less than coca cola, or apple juice? And why does the iron in the apple juice turn black? Coca-Cola and apple juice have a lower pH than water. Low pH solutions will rust iron faster, and the reason it turns black in apple juice is much like a blue and yellow marker make green; the compounds in apple juice, when mixed with iron, form a material black in color.

I have an indoor water fountain with metal cups are now rusting...” To remove the rust, drain the fountain let it dry, Go buy CLR and a stiff brush rinse and scrub. As for preventing the rust from coming back, the short answer is there's nothing you can do.

Post 171

if i put an iron nail in hydrochloric acid and another in sea water (salty water) which would rust more?

Post 165

I am doing a science experiment. What will rust faster in just plain tap water - an iron nail or a small piece of steel wool? I am guessing steel wool because of the surface area. Can anyone verify this for me? Thanks so much!

Post 163

If a piece if rust is say, 1mm (0.039'') thick, what thickness of steel has been lost? I have heard a wide variance of answers, so is there a definitive one please?

Post 162

someone asked how does rust harm you. here's the answer: it doesn't. it harms metal.

Post 150

Thanks for the info!

Post 148

How does rust harm you?

Post 147

thanks this really helped because I am doing a science fair project on how to make a nail rustproof. all of this information was very helpful!

Post 146

This really helped me with my science project I'm working on. now we needed five references and I have picked up the most and interesting facts on this website. hopefully my teacher will think my project is decent.

Post 145

can liquids form rust?

Post 143

what chemical and physical changes happen to metal when it rusts?

Post 142

I have a indoor water fountain with metal cups which is where the water flows over. The metal cups are now rusting and I would like to know how to remove the rust and refinish the cups so they won't rust anymore.

Post 141

This really helped me! I am so thankful I've been looking for a long time for information about rust.

Post 137

I'm doing a science fair project on "which liquid rusts nails the fastest, water, vinegar, coke, or orange juice. I don't know what to start researching. What do I do?

Post 136

Why do nails rust with exposure to salt water and not to vinegar?

Post 135

Rust is formed by oxidation and oxygen mixing together on the surface of metal or iron cause it to become bumpy and brown-red like.

Post 134

Is rust bad for your health?

Post 133

How can we make rust on metal without water?

Post 132

how do you remove rust?

Post 131

I have a problem concerning rust on aluminum?

Anybody know of a cause, please help me.

Post 128

can fizzy drinks make something rust and why?

Post 127

why does rust gives a reddish color?

Post 124

here we know about rust. it's very easy to learn.

Post 123

what procedure should I use to make iron rust with which liquids?

Post 122

Apparently coca cola can help remove rust. does anyone know if tap water causes rust more than coke?

Post 120

i don't understand. Can any substance make something rust?

Post 119

it rusts faster when the plating is scratched off

because it opens the pits and pockets and lets the water and air flow through it quicker.

Post 118

i highly disagree that rust grows faster in salt water. it grows quicker in regular water.

Post 117

rust grows quicker in salt water. a good experiment would be: air, water, salt water.

Post 116

rust is bad.

Post 115

OK I am doing a science experiment and does vinegar, tap water, or Sprite make a fishing hook rust the fastest?

Post 113

how can i separate the mixture of rust and magnetite layer?

Post 112

I just did an experiment and I found out that vinegar will rust things the most in four weeks.

Post 108

i need help badly. what helps rust grow the fastest? lemon juice, water or vinegar? please respond. Quickly!

Post 107

thanks heaps. that's really good.

Post 106

I am also doing a science experiment. Which metal )steel, aluminum, copper) will rust the fastest in water, lemon juice, and ammonia?

Post 105

Are there any environmental effects of rust?

Post 104

one way to get something to rust is to fill up a cup with water. Then put a nail in the cup filled with water. Once you do that put in salt. After that sit back and watch the nail rust away.

If it doesn't I recommend using a different kind of salt.

Post 103

How do different liquids affect the amount of rust on metal?

Post 102

I'm doing the following experiment: I put

in four cups different materials like: a penny, a bolt, a paper clip, an aluminum. Then I put a little bit of water in each cup. In each cup I put different drinks like: water, water with salt, coke, orange juice, vinegar. In those materials I put five pennies, a bolt, paper clip and aluminum. How can I do this project? What is the problem, hypothesis,procedure, data, what's happening and conclusion. If I have a question, can I write you again?

Post 101

I'm also doing a science fair project (which is a huge pain in the but by the way!), but this site has helped me a lot. You see, my project is on what dissolves the rust on a rusty nail the most: bleach, water, baking soda, salt or sea salt.

Post 100

I'm doing a science fair on which dark soda will remove rust from a rusted nail the fastest and i want to know how long it takes so i can see how long i can keep an eye on it.

thank you so much! this site helped me a whole bunch! -Kayla

Post 99

Why does water rust less than coca cola, or apple juice? And why does the iron in the apple juice turn black?

Post 98

Which liquid will rust a nail the fastest, tap water, lemon juice or coke?

Post 96

This has really helped me with my science fair project.

Post 95

I'm doing a science project on what makes a nail rust faster: tap water or salt water? could you tell me how long it usually takes a nail to rust so i can figure out when i need to get it done?

Post 94

i have six test tubes. One contains tap water, the other distilled water, the other distilled water with salt, the other distilled water with oil, the other dry sand and the final one wet sand and all off them had one nail inside. i would want to know the effects.

Post 93

I would like to know if you using a rusty hair clip in your hair would affect your scalp, and your hair growth.

Post 90

This website really helped me with my project.

Post 86

Some metals that can rust are steel, copper and bronze. But anything with iron in it will rust.

Post 85

i am doing a science fair project and i would like to know what metals can rust.

Post 84

can a nail rust in fresh water?

Post 82

I need to know what gets rid of rust faster?

vinegar or baking soda? please let me know. Thank you. (:

Post 81

i read this thing where you put 4 tsps. of bleach and 2 tsps. of vinegar into a jar with whatever you want to rust, fill it up with water just past the metal. it'll rust in about 5 minutes.

Post 79

can rust form on any steel?

Post 76

I can't find ten good facts about rust. can you help me? i am doing a science fair project. please help.

Post 75

Can rust be immediate or does it take a few days?

Post 74

How does rust get in iron or steel?

Post 72

why don't you give the author because people are using this as bibliogrophy and you have to have the author for that! Duh!

Moderator's reply: The author's name is at the bottom of the page. Please check below the boxes for posting replies. It will say, "written by" and will give the author's name.

Post 70

Thank you for the information. This is just what i needed. Thank you.

Post 69

rust is browny orange.

Post 66

Oh gee, thank you so incredibly much. I am doing a science project, and this information will definitely help me ace it! Go science!

Post 64

hey thanks so much. doing a science project and this will totally get me to the county fair. Thanks so much!

Post 62

The term "rust" refers only to oxides of iron - therefore it is not correct to refer to oxides of other metals (such as aluminum and copper) as rust.

In addition oxidation is the processes by which rust, and other oxides, are formed - therefore the first sentence is also incorrect. It would be more accurate to equate "rusting" and "oxidation", however only when referring to iron.

Post 61

Please can you tell me the outcome of the following reactions with their equations:

1) Iron left to rust for a few days in Aqueous HCl.

2) Iron left to rust for a few days in Aqueous NaCl.

3)Iron left to rust for a few days in Aqueous

HNO3(Nitric Acid).

4) Iron left to rust for a few days in Aqueous

NaNO3(Sodium Nitrate).

Post 60

How long it would it take enough rust to build up inside a 100 lb. oxygen tank to cause it erupt when full?

Post 58

i'm going to do a project called 'which metals will be effected by salty water?' can you tell me what grade project this is, because i want to do like a 6th or 7th grade project although i'm in 5th grade? can you please explain this to me in some easier words?

Post 57

I am about to do an experiment involving the rusting of nails.

Can you tell me of an unusual way to rust nails?

I will be using 4 test tubes.

One will have a galvanized nail and the rest will be regular iron nails.

Thanking you,


Post 56

i'm doing a project about oxidation of *rocks* and i have no idea what it is! please help. it would be really nice 'cause I found oxidation pictures but no info... thanks!

Post 55

I am doing a project on what how does coating an iron nail with nail polish affect the rate that it will rust in vinegar? - Briana 4th grade

Post 52

i'm doing a science project. so how could you prevent metal from rusting without paying the price?

Post 50

Is rust another metal on top of the metal when the water hits it?

Post 49

is rust harmful to the skin?

Post 47

does salt water rust metal?

Post 44

which kind of liquid rusts iron the fastest? -Michael, 7th grade

Post 43

why do we get tetanus? is there anyway to prevent from this disease?

Post 41

1 Do you think iron would rust slowly, quickly, or at all in distilled water?

2 I am doing an experiment trying to find out in what type of water iron would rust the fastest; we are doing so with iron nails and salt water, tap water, and distilled water... should I leave the iron nails in the water the whole time, or occasionally remove them from the water?

3 How long do you think an experiment like this would take?

Post 39

Wait, so are there any other substances (other than steel or iron) that can have rust grow on it?

And does the original way of using baking soda and vinegar actually take off 100% of the rust on any substance?

Post 35

wait so the scientific name is oxidation?

Post 34

I am doing a report and this will definitely help me get a good grade!!!

Post 33

what are the 2 types of rust?

Post 28

What is the most efficient way to treat rust. Please reply. I have an assignment on this.

Post 27

why is it that only metals experience corrosion? what is it about their structure that makes them experience corrosion?

Post 24

Well robbi i think it is because there is more area for the water and oxygen to get to create more rust. Nick Rodriguez 8th grade

Post 23

1. How does chemical change take place(from metal+water+oxygen = rust)?

2. Why does the metal rust more when the plating is scratched?

Post 22

i heard that heat and sand get rid of rust or just keep scrub it the rust with warm water and then i think that should do it.

Post 21

What gets rid of the rust?

Post 18

what are the positives & negatives of rusting ?

Post 17

I know the answer to some of these Q's:

1. No, It's not bad for you.

2. I don't think so, but I'm not sure.

3. No, the gas in it is CO2, (Carbon Dioxide) the fizziness does nothing unless the Coke is mixed with O2. (Oxygen)

4. Copper, iron and steel rust orange/red because that is how the oxygen mixes with the metal.

5. Paint and oil are great substances for prevention of rust.

6. It depends how much O2 is in the air that you put the rusting metal in.

Yours Faithfully,

Dr Ryuta Kawashima

P.S. Is Mascara good for the bugs on your eyelashes?

Moderator's reply: thanks for all those answers to your fellow readers' questions! i have heard about Demodicids, mites that live in hair follicles, particularly, eyelash roots. they prefer people who use a lot of makeup and don't wash it off regularly! but that's a whole other article!

Post 13

how long does the rusting process take?

Post 12

how can rust be prevented w/ just a simple substance?

Post 11

What gives rust its orange-red color?

Post 10

can coke make something rust?

Post 9

Does the presence of sodium speed up the rusting process?

Post 1

Any health effects upon exposure to deep well water containing rust due to corrosion in the pipeline?

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