Why does a small scratch on the car door require painting the entire door?

[SpencerFitz]

The reason why a small scratch on the car door requires painting the entire door is due to color matching issues. Except for the front and rear bumpers, which can be partially painted, the rest of the car's surfaces must be painted entirely. Below are the relevant details: Precautions after painting: After painting, be cautious about insufficient drying time. Do not wash the car before the paint is fully dry. Avoid contact with chemicals and oil stains, as they can easily damage the paint. Try not to cover the newly painted area with a car cover, as it may cause fine scratches. Park the car in sunlight as much as possible, as it helps the paint dry thoroughly. Functions of painting: Protects the car from erosion by various atmospheric corrosive agents, enhances the car's appearance, identifies the car's type, improves comfort and sealing, and prevents noise caused by vibrations.