Let me start with a question.
1．A coastal area with salty sea air containing high levels of salt
2．A desert with intense ultraviolet rays from direct sunlight
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The correct answer is the coast — by far.
You might imagine that deserts are harsher environments and therefore more damaging.
And it’s true that paint, plastics, and rubber are vulnerable to ultraviolet rays and sand abrasion.
However, metal is a different story.
Moisture, which causes rust, and salt, which accelerates corrosion, are both scarce in deserts.
As a result, deserts are actually environments where rust is less likely to occur.
Rust is caused by moisture and oxygen.
Why does metal rust when water is present?
The answer lies in a mechanism called an electrochemical reaction.
When metal comes into contact with moisture and oxygen, microscopic electron exchanges begin on the surface.
The metal loses electrons and dissolves as ions — a process called oxidation.
Meanwhile, water and oxygen receive those electrons — a process called reduction.
This exchange of electrons creates an electric current that gradually dissolves the metal over time.
That is the true nature of rust (corrosion).
Normally, metal forms an oxide film on its surface to block this electrical activity.
However, once that protective barrier is damaged, the reaction accelerates rapidly.
Salt accelerates rust.
Recently, there have been news reports about aging streetlights collapsing in various places.
What’s interesting is that even though the streetlights were installed at the same time, the level of corrosion differed from one to another.
Believe it or not, dog urine was found to be accelerating the corrosion.
The reason is the salt contained in the urine.
Salt dramatically increases the electrical conductivity of water.
As a result, it greatly accelerates the electrochemical reactions mentioned earlier.
Should you wash your motorcycle, or not?
“If water causes rust, wouldn’t it be better not to wash your motorcycle?”
“Would dry wiping or wax alone be better?”
Some people may think that way.
The answer is no.
In fact, washing your motorcycle actually helps prevent rust.
What accelerates corrosion the most is allowing moisture and salt (chlorides) to remain on the bike.
Washing removes the substances that cause rust — it resets the conditions for corrosion.
Of course, water itself can contribute to rust.
That’s why drying the bike afterward is important.
However, completely removing water trapped in small gaps is difficult.
Unless you have a compressor and air gun, getting rid of every last bit of moisture is nearly impossible.
Still, clean residual water left after washing is far better than leaving salt and grime on the bike.
