How to Determine If the Primer is Damaged?
3 Answers
It can be observed with the naked eye. Methods to determine if the primer is damaged are as follows: 1. Primers are usually black, gray, or white, and these colors are generally opposite to the car paint color. If the car paint is scratched, there will be a noticeable color difference. If the scratch penetrates to the primer, it can be clearly seen. 2. You can run your fingernail over the scratch to feel the depth. If it feels slightly rough with a shallow indentation, it usually means only the surface paint is scratched, and the primer is intact—polishing and waxing will suffice. If the scratch can catch your nail as it slides, it indicates a deeper scratch, and there's a higher likelihood the primer is damaged.
I often wash and wax my car myself, so I have some experience in this area. The key to determining whether the primer has been damaged is to look for color differences. You can stand in a well-lit area and shine a flashlight sideways at the scratch. If the scratch reveals a completely different grayish-white or dark gray color underneath compared to the car's body color, it's likely that the primer is exposed. Another method is to gently run your finger over the scratch. If you feel a noticeable step-like depression at the edges or if it feels rough like sandpaper, it's highly probable that the primer has been damaged. Additionally, observing signs of rust is very straightforward—if you see red iron rust, there's no doubt that the primer has been completely compromised. When parking, it's best to avoid areas with many tree branches, as tree sap can also accelerate paint aging.
As a veteran driver with ten years of experience, I believe judging primer damage requires a combination of methods. The most intuitive way is to compare colors. For example, when my black car's primer is damaged, it reveals a grayish-white metal layer. You can also use your fingernail to scrape the edge of the scratch—if your nail gets caught, it means the depth exceeds the paint thickness. When drying the car with a towel after washing, pay attention to areas where water droplets get trapped in grooves and don't flow away, as these are likely deep damages. If you notice bubbles forming at the edges of the scratch or yellow rust spots appearing, it's even more urgent to address it. Actually, avoid using hard-bristle brushes when washing the car, as many scratches are caused by washing.
