Abstract: A method and apparatus for making a chemical mechanical polishing (CMP) article dissolves gas into solidifiable material, and reduces pressure on the solidifiable material to form gas bubbles therein while solidifying the solidifiable material to make a matrix with voids therein. The gas bubbles are preferably formed to define voids interconnected with adjacent voids to thereby define a porous matrix. The porous matrix ensures uniform distribution of the CMP slurry for greater polishing uniformity. The method produces a CMP pad, for example, with very uniform porosity throughout its thickness so that polishing remains uniform as the pad is consumed in use. The gas and the solidifiable material may preferably be non-reactive with one another. The gas may comprise at least one inert gas, such as nitrogen or argon, for example. The solidifiable material may be a polymer-forming liquid and at least one of a curing and cross-linking agent mixed therein.