Does Car Painting Require Removing the Original Paint?

[MayaMarie]

Car painting requires removing the original paint for the following reasons: 1. Repainting increases the thickness of the paint film; 2. The painted area will be higher than the surface of the original paint; 3. The new and old paint may separate and peel after blending; 4. The new paint is prone to peeling during car washing; 5. Color differences may occur. Precautions after car painting include: 1. When washing at a car wash, ensure the attendant does not use wax-removing detergents to avoid damaging the paint; 2. Vehicles driven in coastal or heavily polluted areas should be rinsed daily; 3. Use clean, soft cloths or sponges for washing to prevent metal shavings and sand particles, and avoid using dry cloths, towels, or sponges to prevent scratches.

[DelLeila]

I have some experience with this, having seen quite a few cases while helping out at a friend's repair shop. Whether to sand the original car paint depends on the specific situation. For spot repairs, like a small scratch on a door, the technician usually only sands the damaged area, removing the old paint to expose the base layer. However, for a full respray or color change, the entire original paint must be sanded down a layer, or the new paint won't adhere properly. I remember one time a car owner skipped the sanding, and within six months, the paint started bubbling and peeling. The original paint surface is too smooth; without sanding, the new paint just sits on top, and issues become apparent after just a few washes. Color matching is also crucial—getting the shade right is essential.

[StWalter]

Last year, my car roof got scratched by tree branches, so I tried fixing it myself with a spray paint can. At first, I thought the original paint was fine, so I sprayed two coats, but it started peeling off soon after. Later, I learned from an experienced mechanic that before painting, you must sand the original paint—even if it looks fine—to roughen the surface so the new paint can adhere properly. The original car paint has a clear coat layer, and spraying new paint directly on it is like applying pigment on glass; it washes off easily. Professional repair shops always use sandpaper or specialized tools to sand off a layer. For small areas, they sand locally, while larger areas require full-vehicle treatment. Otherwise, bubbles and peeling may occur later, leading to rework and extra costs.

[MacAlan]

Sanding the original car paint before repainting is crucial. After prolonged exposure to wind and sun, the car body develops an oxidized layer or fine cracks on the surface. Applying new paint directly over this results in poor adhesion. Professional technicians always sand off the top layer of the original paint to roughen the surface, ensuring that the primer adheres firmly. Otherwise, even the highest-quality topcoat will peel, allowing rainwater to seep in and cause rust on the steel panels. I once saw a car that wasn't sanded properly, and its paint started cracking and peeling within three months. Whether you're fixing scratches or changing the car's color entirely, this step cannot be skipped.