possible stupid question on rust

[funkman]

Is rust a breakdown of a relic or a buildup on a relic? I have a buckle that I am soaking in oil that is heavily encrusted in rust. Someone mentioned to me that they do this with buckles and other relics, soak them for days and then lightly sand the rust off with fine sandpaper. This brought up the question in my head about rust. I was wondering if the rust is built on top of the relic and but removing the rust I will see the relic almost exactly when it was lost, or will the relic be missing sections or have the original metal missing due to the rust actually eating away the original metal?

Thanks for answering my stupid question

Funkman

 

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[Gypsy Heart]

First of all, lets just define rust. Rust occurs when iron combines with oxygen to form iron oxide. There are different types of iron oxide but rust forms only when there is plenty of oxygen available and is characterised by that red-brown colour.

Now iron will not react with the oxygen in the air. Do you remember when you were in kindergarten? Your teacher probably asked you to hold hands with another child when you went outside. Well in air an oxygen travels around in partnership with another oxygen. In this combined state the oxygen in the air does not react with iron.

When the oxygen in the air dissolves in water (this oxygen is what allows fish and other aquatic life to breathe), each oxygen separates from its partner and goes round on its own. Iron can combine with oxygen in this singular state and does so.

So iron does not react with water; it reacts with the oxygen contained in the water. You can prove this with a simple experiment:

1) Place an iron nail in a test tube with water

2) Place an iron nail in a test tube with recently boiled water (boiling removes the free oxygen in the water)and seal it with a rubber bung to prevent any oxygen getting in.

3)Place an iron in a test tube with oil (oxygen cannot dissolve in oil)

4)Place an iron nail in a test tube with a small amount of calcium chloride to keep the air dry and seal the test tube to prevent continued moisture entering.

Only no. 1 will show rusting.

and here is a more lengthy explanation
Rust is the common name for a very common compound, iron oxide. Iron oxide, the chemical Fe2O3, is common because iron combines very readily with oxygen -- so readily, in fact, that pure iron is only rarely found in nature. Iron (or steel) rusting is an example of corrosion -- an electrochemical process involving an anode (a piece of metal that readily gives up electrons), an electrolyte (a liquid that helps electrons move) and a cathode (a piece of metal that readily accepts electrons). When a piece of metal corrodes, the electrolyte helps provide oxygen to the anode. As oxygen combines with the metal, electrons are liberated. When they flow through the electrolyte to the cathode, the metal of the anode disappears, swept away by the electrical flow or converted into metal cations in a form such as rust.

For iron to become iron oxide, three things are required: iron, water and oxygen. Here's what happens when the three get together:

When a drop of water hits an iron object, two things begin to happen almost immediately. First, the water, a good electrolyte, combines with carbon dioxide in the air to form a weak carbonic acid, an even better electrolyte. As the acid is formed and the iron dissolved, some of the water will begin to break down into its component pieces -- hydrogen and oxygen. The free oxygen and dissolved iron bond into iron oxide, in the process freeing electrons. The electrons liberated from the anode portion of the iron flow to the cathode, which may be a piece of a metal less electrically reactive than iron, or another point on the piece of iron itself.

The chemical compounds found in liquids like acid rain, seawater and the salt-loaded spray from snow-belt roads make them better electrolytes than pure water, allowing their presence to speed the process of rusting on iron and other forms of corrosion on other metals.



Both these answers found on the net...because while I am extremely adept at finding rust...I am not good at explaining why....

 

[TreasureTales]

Uh, I think Gypsy has explained the process by which rust occurs. And a mighty fine job she did!!

But to answer your question , I think rust can only form when the iron is compromised. Therefore rust indicates a breakdown of the metal and therefore a pit will occur. Removing the rust in effect removes some of the metal as well. This is not necessarily a problem, though, because by removing the rust you can get down to the stable portion of the object/metal. Sometimes items will be "eaten up" by rust, but when they reach that stage things are usually unrecognizable anyway. Soaking or electrolysis or sanding or whatever precedure you use to clean up an item will most likely take some of the surface metal off with the rust, but you will probably have a better looking item in the long run. So although rust appears to add a layer onto the surface of an item, it is really breaking down the surface of the item and will result in a net loss of the metal itself. Don't know if this helps or adds any additional info for you, but I'm not a scientist and must explain things in the way only way I know...the basics.

 

[stefen]

A stupid (and dumb) questions are those that are not asked.

However, there is always the possibility to receive a stupid or dumb answer or response.

In this case, your question has received two (2) valid, explicit and concise answers.

I consider my day to be successful if I have learned at least one thing that is new.

 

[jeff from east pa]

Your question is a good one I dug alot of civil war relics made of iron. First once you dig the item out of the ground it well start to decay. because the air is now getting to it. if the item is not crusted to bad i well clean it with a wire brush then coat it with polyurethane. If its really incrusted you electrolysis my spelling is not that great. basic items needed for this is baking soda ,car battery charger, 5 gallon bucket, 2 brass rods. and some brass wire to wrap your item in this is the best way to clean your item and it only takes about 24 hours It well do a fantastic job .it eats away all the rust and lets the iron or steel intact. If there's anything good under that blob of rusty iron you well see it after your done. this is the same process the museums use. you can find out how to do this exactly by going on yahoo search and type in how to use electrolysis on relics. good luck jeff