A clay bar is a tool used in the detailing process of automotive care. It's a specially formulated resin compound that feels somewhat similar to plasticine. When glided across the surface of a vehicle with a lubricant, it picks up and removes contaminants from the paint that washing alone cannot remove. These contaminants can include things like industrial fallout, brake dust, and other airborne particles that can stick to your car's surface.

Using a clay bar can help to create a smoother and cleaner surface, making it easier for waxes and sealants to bond with the paint, thus enhancing the protection and shine of the vehicle. It's an important step in preparing a car's surface for polishing or waxing.