Arpita's family repaints their iron gate every two years
Arpita's family repaints their iron gate every two years. Arpita says the paint is only for looks — the gate stays strong because the iron is thick. Her neighbour Baldev points to a spot where the paint got scratched last year: the iron there has turned brown and is flaking, while the painted parts are fine. He says the paint is what protects the gate. Who is right?
Who do you think is right? Pick one.
The answer: Baldev is right, paint stops rust by keeping air and moisture off the iron
Why
Arpita is correct that a thick gate takes longer to rust all the way through, and paint does make it look nice. But thickness only delays the damage; it doesn't stop it. Rust forms when iron is in contact with both air (oxygen) and moisture, and it eats into the iron layer by layer, flaking off and exposing fresh iron underneath. Paint works by covering the iron so that air and moisture can't reach it. Baldev's scratched spot is the evidence: same gate, same thickness of iron, same weather — the only difference is the missing paint, and that is exactly where the rust is. Test: this is why iron railway bridges, electric poles and window grills are repainted regularly, and why iron buckets and pipes are often galvanised, that is, coated with zinc. Baldev is right: the paint protects the gate by keeping air and moisture away from the iron, which stops rust.
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