Will exposed primer rust?
2 Answers
Exposed car primer will rust over time. 1. Exposed primer: If after a "collision", the primer or paint that is significantly different from the exterior paint (sometimes the metal part can be seen) is clearly visible, then touch-up painting is necessary. If left untreated for too long, it may cause internal "rusting" and expand the "repair area". 2. Plastic parts: If the collision or scratch occurs on plastic parts such as the front and rear bumpers of certain models, touch-up painting can be done if personal aesthetics are a concern. However, for small areas (not affecting overall appearance) or situations that can be handled by polishing, touch-up painting is unnecessary, and there is no risk of rust (plastic parts).
I found that exposing the primer doesn't necessarily lead to immediate rusting, but the risk is high. The primer itself contains anti-rust components that can temporarily isolate air and moisture, so scratches revealing the primer might not cause issues initially. However, if the primer wears thin or peels off, exposing the underlying metal body, rust becomes likely—metal oxidizes in humid environments, such as when car wash water seeps in or during rain, and rust spots can appear within days. When helping friends deal with similar issues, I always remind them to check the depth of the damage: shallow scratches may only affect the surface paint, leaving the primer intact and rust-free; deeper damage exposing the steel plate requires caution. The preventive method is to spray a layer of rust inhibitor immediately—don't delay, as rust can spread and affect the frame's lifespan, eventually requiring a visit to the paint shop for repairs.
