Does Replacing a Trunk Lid Require Painting?

[MacHarrison]

Replacing an original trunk lid requires painting because the original trunk lid does not come with a painted surface. Therefore, it needs to be painted at the 4S shop before installation. The automotive body paint is complex and consists of four layers. From the inside out, they are the electrophoretic layer, the primer layer, the base coat layer, and the clear coat layer. Each layer has its unique painting process and function. Electrophoretic Layer: After the entire car body is assembled, robots immerse the body in an electrophoretic tank to form an electrophoretic layer. The main function of this layer is rust prevention. Primer Layer: After the electrophoretic layer is formed on the body surface, robots spray the primer layer. This layer also serves to prevent rust and enhances adhesion to the next layer of body paint. Base Coat Layer: Above the primer layer is the base coat layer, which primarily serves an aesthetic purpose. The various car body colors we see daily are presented by this layer. Clear Coat Layer: The outermost layer is the clear coat, which protects the base coat and enhances its gloss. The clear coat is the most vulnerable layer, as most minor scratches typically remain on this layer.

[Roy]

I just watched the mechanic replace the rear tailgate at the repair shop. To be honest, the new part is just a bare metal panel, exactly like the unpainted car shell frame when newly purchased. If you don’t paint it after replacement, it’s like going out wearing ripped pants—not only ugly but also prone to rust. My neighbor didn’t paint it last time, and within six months, it rusted into a ‘map.’ The experienced mechanic specifically warned that the edges and seams must be properly treated during painting; otherwise, rainwater seeping into the gaps would cause even bigger trouble. Color matching is even more critical—with so many pearl and metallic paints nowadays, a significant color difference would make it look like a patch job. I suggest asking the shop for a color difference inspection report after replacement—it’s worth the money.

[SerenityAnn]

Last month, I backed into a tree and had to replace the entire rear hatch. The repair bill showed that the painting cost accounted for a third of the total. I was initially upset about the expense, but the technician showed me photos of the new replacement part—it was just plain silver aluminum alloy! There are inherent color variations between different batches of car paint, and if they had installed it as-is, it would have clashed with the decade-old paint on my car. The painter specially mixed three versions of the color for comparison under daylight, even adjusting the metallic flake ratio for the transition areas. Now, the texture feels uniform to the touch, but upon closer inspection, there’s still a slight shade difference at the seams—like the faint line after painting nails. I’d recommend keeping an eye on them during the blending process.

[Hazel]

Don't believe that nonsense about paint-free installation! I've been modifying cars for seven years, and every replacement hood, door, and bumper needed repainting. OEM new parts come with anti-rust wax - if installed directly, they'll bubble within six months. A buddy at a body shop taught me this trick: when installing a new tailgate, supervise the technician to ensure proper corner putty work - skipping this step causes future cracking. Paint job prices depend on materials: regular paint costs 400-500 RMB, metallic paint runs over 1,000 RMB. If you just want quick cover-up without caring about quality, you can buy spray paint from Taobao, but it definitely won't last.