Foam wash is a variation of car shampoo formulated specifically to generate a massive amount of thick, stable suds. While it can be used in a bucket, it is optimized for creating a slick barrier between the wash media and the paint. The dense bubbles help lift dirt particles away from the surface, suspending them in the lather so they can be rinsed off safely. It provides a visual guide to ensure you haven’t missed any spots during the washing process.