What is the method to determine if the primer is exposed?
3 Answers
Determining if the primer is exposed involves: gently touching the scratch with your finger; if you can feel a noticeable unevenness, it indicates that the primer is exposed. The automotive primer is the first layer of paint applied directly to the surface-treated base component. It serves as the foundation of the entire coating system. The primer is designed to have excellent adhesion to the substrate and good compatibility with the intermediate or topcoat layers above. Additionally, it must possess strong anti-corrosion, anti-rust, oil resistance, chemical resistance, and water resistance properties. Solvent-based automotive primers primarily use nitrocellulose resin, epoxy resin, alkyd resin, amino resin, or phenolic resin as the base material. Pigments such as iron oxide red, titanium white, carbon black, and other fillers are used. The application methods include spraying and dipping.
I used to frequently inspect the car body myself, and judging whether the primer is exposed is quite simple—mainly by looking and touching. First, observe any color changes on the car's paint surface. If small grayish or whitish spots appear in areas that were originally dark or bright-colored, especially deep within scratches, it's highly likely that the primer is exposed. This is because primer is usually much lighter than the topcoat, with gray or white being the most common colors. Next, gently run your fingers over the surface. If it feels rough instead of smooth, or even slightly powdery or prickly—whereas the original paint is smooth—it indicates exposed primer. Shine a flashlight at an angle to check the reflection; uneven or dull spots can also reveal exposed primer. Early detection is crucial because prolonged exposure of the primer to wind and rain can lead to rust, which then becomes a serious issue for the car body. I recommend taking an extra couple of minutes during car washes or maintenance to carefully inspect scratched areas, paying special attention to edges and corners.
Hey, I'm a car enthusiast who often chats about vehicles. The key to determining whether the primer is exposed lies in visual identification and a few small tricks. Observe the car body from multiple angles, such as tilting your body under sunlight. The paint surface usually reflects light brightly. If an area appears matte or the color turns lighter and grayer, there's an 80% chance the primer is exposed. Comparing it with the original paint color can reveal obvious differences. Gently touch the damaged area; if it feels rough instead of smooth and comfortable like other parts, that's a signal. Rust forms quickly once the primer is exposed, so if you spot small red spots or rust emerging, it's even more certain. No tools are needed for inspection, but details are clearer under strong light. Make it a habit to regularly check areas prone to scratches, and don't wait until the damage worsens to take action. Simple maintenance can save you from big troubles.
