Yes, you can polish a car without claying first, but it's generally not recommended for achieving a truly professional finish. The primary risk is that you'll be grinding bonded contaminants—microscopic particles of rail dust, brake dust, and industrial fallout stuck to the paint—into the clear coat with the polishing pad. This can create new, fine scratches (swirl marks) that undermine the goal of polishing, which is to remove existing defects.
Think of it like sanding a wooden floor without sweeping it first. You'd be rubbing dirt and grit across the surface, causing more damage. Claying is the essential step that safely lifts and removes these embedded particles, leaving a perfectly smooth surface. When you run your hand over a contaminated panel, it feels gritty; after claying, it should feel as smooth as glass. This smooth base allows the polish to work exclusively on leveling the clear coat to eliminate scratches and defects, not on pushing dirt around.
If you're in a pinch, a thorough wash with a strong stream of water and a high-quality car shampoo can remove some loose contaminants. However, the "bag test" (putting your hand in a plastic sandwich bag to feel the paint's texture) will quickly reveal if claying is necessary. For a quick enhancement or on a heavily contaminated car where you plan to compound and polish anyway, you might proceed, but understand the compromise. For a true, scratch-free correction and the deepest gloss, claying is a non-negotiable preparatory step.
