Why Road Salt Causes Corrosion and How You Can Stop It from Rusting Your Vehicles?

It doesn’t take a lot to cause rust. A lot of environmental elements like salt and corrosion will lead to this one way or another. As a car owner, you should probably know that responsible and proper car maintenance shouldn’t end with just detailing.

Auto rustproofing is another car service that is equally as important. Let’s face it. A beautiful shiny car is useless if it’s falling apart because of decay on the inside. Road debris, salt, corrosion, and other environmental pollutants can cause this.

Annual rust checks are vital if you want to provide your car with a durable protective layer against any rusting process.

You have to make sure that your ride is always well-protected. Researching new rustproofing products and services is a good start in understanding better rust prevention. You can also start at the root, what causes rusting in the first place?


Salt, water, and corrosion chemistry = rust!

Before going through dozens of different rustproofing services and buying all the rustproofing products you see, it’s best to know what causes rust in the first place. The answer is, not much.

All you need is water, oxygen, and iron. Rust forms as a result of the oxidation of iron. That’s why its chemical composition (or chemical name) is iron oxide. The environment of your car is a big factor in how fast rust formation accelerates.

If you live somewhere that snows in the winter, rustproofing your car is a little bit more challenging. That’s because the government uses calcium chloride (a form of salt) to deice the roads. Do salts corrode metal, true or false? Unfortunately, true!

Good thing like rust converters and rust inhibitors now exist. With the right products, you can keep your vehicle well-protected from the unwanted effects of rust.

So, in this article, we’ll explore:


What is Corrosion?

salt fog

Corrosion is the deterioration of a metal because it chemically reacts with the environment it’s exposed in. How accelerated corrosion occurs depends highly on what type of gases it comes in contact with.

There are many types of corrosion, and they happen for various reasons. Some of these types are:

  • Uniform Attack Corrosion
  • Galvanic Corrosion.
  • Crevice Corrosion.

No matter the type of corrosion that happens, one thing is for sure. All metals corrode. Therefore, your car is highly susceptible to it. Pure iron corrodes fast. However, stainless steel corrodes as well; albeit, a little slower.


Why Does Saltwater Corrode Metal?

The chemical composition of salt is NaCl, or sodium chloride. It is made up of a sodium ion (which has a positive charge) and a chloride ion (which has a negative charge). Together, they create a neutrally safe compound.

The attraction between the sodium and chlorine ions causes them to come together in such a manner as to produce an ionic bond. Large numbers of these ions come together to form a giant ionic lattice, for which the symbol is NaCl. Alone, both sodium and chlorine are poisonous and highly reactive with oxygen, but the combination of the two forms a neutral, safe compound. – The Hitchhiker’s Guide to the Galaxy: Earth Edition

Saltwater is made up of many salt compositions like sodium chloride. It also contains magnesium chloride and sodium sulfate among many others. But how do these affect salt water corrosion of metals?

When saltwater and metal react, a process called electrochemical corrosion occurs. The ions found in metal dissolve in water. Saltwater also contains ions and is an excellent conductor of electricity. When this happens, the ions in saltwater attract the ions from other compounds which in turn are attracted to the metal’s ions. That is when corrosion occurs.

You can even witness this by conducting a salt water rust experiment. There are many rust experiment videos on Youtube that you can get inspiration from. Here is a rusting of iron nails experiment you can watch just to see how corrosion works.



How Does Salt Speed Up Corrosion?

While the water, oxygen, and iron combination basically make rust, mixing moisture, oxygen, and salt damages metals much worse. Saltwater can eat away and weaken metals five times faster than fresh water.

…the salty, humid ocean air causes the metal to corrode 10 times faster than air with normal humidity. Bacteria in ocean water also consumes iron and their excretions turn to rust. – Sciencing

During rust formation, electrons move. Saltwater has more dissolved ions in its composition which allows these electrons to move more freely. Because of this, rust forms faster.


Why Does Salt Increase Conductivity of Water?

salt spray


When a metal conducts electricity, the electric current is carried by negatively-charged subatomic particles. When a solution is the one doing the conducting, the current is carried by ions. Ions are tiny groups of atoms with an electrical charge.

Water doesn’t have many ions and that’s why it only conducts electricity poorly. Table salt contains ions and when it’s dissolved in water, the saltwater becomes a better conductor. Salt is made up of sodium ions (who are positively charged) and chloride ions (who are negatively charged). That is why the flow of the electrical charge is carried by ions, and not just electrons moving.


How Long Does It Take for Iron to Rust in Water?

Chemical reactions occur immediately once the metal is exposed to the environment and it’s a continuing process as long as it remains exposed. However, the rate of rust formation on your is highly dependent on the type of environment it encounters regularly and the preventive measures you put into place.

For example, how long does it take for iron to rust in saltwater? Again, it depends on the minerals present in the salt water. The more concentrated of sodium chloride or other mineral salts, the faster corrosion progress. So, let say you submerge a metal into the Dead Sea, you will guarantee to have the metal corrode a few times faster than regular sea water.


Why Does Saltwater Rust Iron Faster than Tap Water?

The flow of an electrical charge flows more easily in salt water because it has more dissolved ions in its solution. Electrons moving in saltwater are freer so the metal can rust quicker. That’s why most metals that are submerged in salt water will definitely oxidize more quickly than others.

However, you don’t need to submerge something to increase the rate of rust formation. Increased moisture in the air plus salt can also accelerate corrosion.


Is Table Salt Corrosive?

salt on concrete

Yes, it is.

Sea salt and Table salt are two kinds of salt but they have the same main chemical composition. Sea salt just has a little more variety. Their main difference is that they were mined in different areas.

But that doesn’t change the fact that both table salt and sea salt have positively-charged and negatively-charged particles that form an ionic bond. This ionic bond creates an electrochemical current that makes them corrosive.


Calcium Chloride: Corrosion Effects

Not only is this topic scientifically interesting, it also affects your car and the whole world. The calcium chloride effects on metal can be severe for the transportation industry. In fact, a recent study has estimated that about $6.45 billion is spent on vehicle repairs and maintenance related to corrosion, in the US alone.

But you can’t really blame the government for using calcium chloride. In order to keep you and everyone safe during the winter season, salt is used to fight off the ice, snow, and sleet on the road.

However, it has been discovered that other salt compositions such as calcium chloride and magnesium chloride have lower freeze points. They also cost less and are better for the environment. The only downside is that they cause faster vehicle corrosion, especially on the undercarriage.

A typical vehicle can last you for up to 12 or 15 years but corrosion can considerably shorten its lifespan. Deterioration can be seen quite visibly in the exterior of your car. In fact, driving through deiced roads will instantly change your vehicle’s appearance until you clean them. If not removed entirely, road salt can contribute to exterior rusting.

But that’s not all you need to worry about! Your shoes can also bring calcium chloride and the other types of salt inside your cars via your footwear. Not only can corrosion occur on your paint and undercarriage, it can also inconspicuously occur on your interior as well.


Factors That Affect the Rate of Rusting

corrosion test

Like stated before, there are many factors that affect the rate of the rust and it’s highly dependent on the surroundings, the model of your car, and many more. How accelerated or decelerated corrosion is will really rely on your specific circumstances.

But here are some of the general factors that affect how fast rust formation occurs:

  • Type of Metal. Metals that have higher electrode potentials like gold and platinum rarely corrode. However, metals that have lower electrode potentials like zinc and aluminum corrode easily.
  • Type of Corrosive Result. Sometimes the type of product that results from corrosion is stable and non-porous like metal oxide. These types of products can act as a protective layer from further corrosion. However, unstable and porous products increase the corrosion rate.
  • Temperature. Corrosion increases as temperature increases because conductivity is also increased.


How Can Rusting Be Prevented?

If one of your small metal accessories fall into the water, a simple solution can help you prevent corrosion from happening. Rinse it completely in fresh water and let it dry thoroughly. Give particular attention to the crevices to ensure that no saltwater lingers.

If you’re dealing with metals that are completely submerged in water, make sure that it’s always well coated in oil, kerosene, or anti-freeze to keep them from corroding.

Preventing corrosion from happening can be challenging because it’s such an easy phenomenon to make happen but there are many solutions you can do to stop it. In fact, corrosion prevention will not only help keep your car running for longer, it can also help solve some of the global issues of today.

Economic Lost

Did you know that the world spends about $2.2 trillion every year on corrosion-related problems? You can easily lower that by at least 25% by applying very simple prevention techniques. One way to help salt corrosion removal is to use rustproofing services and products.

Corrosion can also weaken many structures like bridges and buildings. Without the proper maintenance, it can lead to sickness, injuries, and even death. Not only can you help lower the costs in the world and solve a few environmental problems as well, but you’ll also be ensuring that the world becomes a safer and healthier place.

  • Updated October 11, 2018
James Evans

As a passionate outdoorsman and an automobile enthusiast, James spent most of his time in his garage tinkering with cars and bikes. During his free time, he loves to hike and blog about the things that he has done to keep his ride in tip-top condition.

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