Why does replacing the hood at a 4S shop require painting?
3 Answers
Hoods, doors, bumpers, etc., all need to be painted at the 4S shop because they are not painted during transportation. Automotive paint can be classified into the following three types: 1. Standard Paint: Standard paint is the most common type of automotive paint and has been around the longest. Its characteristics include low cost and simple application, but it lacks high gloss and surface hardness, making it particularly prone to scratches. 2. Metallic Paint: Also known as metallic flake paint, it contains fine aluminum particles in its base. When light hits these particles, it reflects off them, creating a sparkling metallic appearance. This type of paint gives a pleasant, light, and modern feel. 3. Pearl Paint: Also called mica paint, it operates on a similar principle to metallic paint but uses mica particles coated with titanium dioxide and iron oxide instead of aluminum. When light strikes the mica particles, it first takes on the color of titanium dioxide and iron oxide, then undergoes complex refraction and interference within the mica particles.
Last time I went to the 4S shop to replace the hood, the staff told me the new cover is actually like a blank sheet of paper and needs to be repainted. The hoods that come from the factory are bare metal sheets with only a layer of anti-rust primer on the surface, which doesn't match the color of our car body at all. They first need to mix the exact same paint color as the doors and fenders, then use professional equipment to spray layer by layer. The most crucial part is the anti-rust treatment—the 4S shop applies coatings both inside and outside, especially in the drainage channels and seams, to prevent rainwater from seeping in and causing rust. If this step is skipped, you'll likely see yellowing and bubbling at the edges within six months, and then you'll have to redo the work, which is even more troublesome. After painting, the hood is placed in a baking room for high-temperature curing to make the paint hardness close to the factory standard.
Buddy, last time my car got front-end damage, the 4S shop insisted on repainting when replacing the hood. New hoods come from the factory as dull metal panels, looking completely different from our car's color. They have to use a spectrophotometer in the paint mixing room to match the old paint, even getting the metallic flakes in pearl paints to align perfectly. And that's not all - after painting, they need to polish it to eliminate orange peel texture until it looks factory-fresh. The most crucial part is metal protection. During transportation, new hoods inevitably get minor scratches, and painting seals these wounds. If installed directly, rainwater would seep into the metal layer and cause rust-through within six months.
