Why does car paint turn white and lose its gloss after polishing?
3 Answers
The outermost layer of car paint is a clear coat, which is transparent and glossy. Improper polishing techniques can damage this clear coat, resulting in a white, dull appearance. Correct car paint polishing method: First, wash the surface of the car paint with car shampoo. Ensure that hard particles like dust are removed, as they can scratch the paint during the polishing process. Then, use wet sandpaper for initial rough sanding of the paint surface. Avoid excessive sanding, as it can damage the paint. Select an appropriate polishing machine and apply polishing wax for the polishing process. After polishing, perform a mirror-finish restoration by wiping the polished area with a mirror-finish treatment agent. Precautions for car paint polishing: Always adhere to the principle of "better slow than fast, better light than heavy" to avoid exposing the primer. Before polishing, it is recommended to use a clay bar to remove surface particles and contaminants from the paint. When polishing the hood, cover the windshield with a large towel or masking film to prevent polishing wax from sticking to the glass seals and wipers, which can be difficult to remove. Control the speed of the polishing machine and do not exceed the selected speed range. Maintain consistent polishing direction and follow a systematic sequence. When changing polishing compounds, also replace the foam pad to avoid cross-contamination.
I've handled quite a few cases of paint turning white after polishing. The main reason is over-polishing – using overly coarse compounds or excessive pressure thins or even removes the clear coat, making the paint appear dull and hazy like it's covered in fog. Polishing compound residue is another common issue, especially with paste or oil-based polishers that weren't promptly cleaned off and dried on the surface, blocking light reflection. Aged paint or previous touch-ups can also cause this when the base isn't sturdy enough to withstand polishing. Environmental factors matter too – like polishing in dusty workshops where particles stick to wet paint and create stains. Also, using worn polishing pads or incorrect machine speeds can overheat and deform the paint, killing its gloss. For proper repair, start with thorough cleaning, reapply clear coat, then finish with a thin layer of coating for protection.
Having worked in the car dealership for so many years, I've handled countless dull and lackluster polished cars. Common mistakes include improper use of polishing tools, such as using a coarse polishing pad with fine polishing compound, which causes excessive friction and damages the paint layer; applying too much polish or leaving it on for too long without wiping it off, leading to a white, chalky residue when it dries; or owners trying to save time by polishing directly without washing the car first, causing dirt to mix with the polishing compound and form white spots. Aging paint is also a hidden danger, especially for cars parked outdoors for long periods, as the paint becomes brittle and more susceptible to damage during polishing. High or low environmental humidity can affect the polishing results, often causing a white haze. The sequence of operations is crucial—polishing in sections, controlling speed, and cleaning promptly are key. After polishing, gently wipe the surface with a soft cloth and then apply car wax or sealant to maintain the shine.
