A. Polyurethane laminated (PUL) fabric is a rather technical term for the thin, shiny, waterproof cloth that makes up the outer layer of many washable diapers. It was originally created for use in hospitals and other medical settings, but it's perfect for cloth diapers, especially since it continues to prevent leaks over the course of many wash-and-dry cycles (even at high heat). This is why many cloth diapering moms recommend it (they also say it works great for bibs). If you buy premade cloth diapers, keep an eye out for an outer layer made of PUL fabric. If you sew your own, there are a number of reliable online sources for purchasing PUL fabric (try sewzannesfabric.com or celticclothswholesale.com). It costs around $9 a yard, and it comes in a multitude of colors and prints.