Why Do Bubbles Appear on Car Paint When It Rains and Disappear When It's Sunny?
2 Answers
Bubbles appearing on car paint during rain and disappearing when sunny may occur after repainting. During prolonged rain, the putty absorbs moisture and forms bubbles, which then subside when the weather clears. This typically does not happen with the original factory paint. Here are some related explanations: Causes of bubbles on car paint: The main reason for small bubbles on car paint is the entrapment of solvent air within the paint film during the repainting process, which later escapes, leaving bubble marks. This could be due to applying the paint too thickly, using inappropriate hardeners or thinners, insufficient drying time for the putty during heating, or uneven baking of the paint. Precautions: Use the correct spraying viscosity, spraying pressure, nozzle size, appropriate hardeners, and thinners. Ensure the putty has sufficient drying time and regularly check the air pressure and humidity in the baking room. Therefore, repainting should be done at professional auto body shops or 4S stores. If small bubbles appear on the paint, it should also be addressed at a professional facility.
Having worked in the auto repair industry for over a decade, I've seen many cases where car paint bubbles up on rainy days and flattens out when sunny. This usually happens due to aging or damaged paint layers, allowing rainwater to seep beneath the base coat and form bubbles. When the sun comes out and temperatures rise, the moisture evaporates, causing the bubbles to shrink back. The root cause is often poor base layer application—like uneven rustproof coating or gaps that let moisture in. If left untreated, rust can deepen, potentially turning bubbles into permanent pits. My advice: don't delay upon noticing this issue. Take it to a professional shop for inspection. Sanding off rust spots and repainting typically solves it. For prevention, park in dry areas, and after rainy-season car washes, ensure thorough drying to avoid this minor hassle.
