Abstract: The present invention provides methods of making a chemical mechanical planarization (CMP) polishing layer or pad comprising providing an open mold having a surface with a female topography that generates a flat or shaped CMP polishing layer surface and having held in place thereon one or more endpoint detection window pieces; mixing a liquid isocyanate component with a liquid polyol component to form a solvent free reaction mixture; spraying the reaction mixture onto the open mold while the one or more window pieces is held in place, with each window piece at a predefined location, followed by curing the reaction mixture.