Smooth milled polymeric foam article

A process comprising:

• (a) preparing the extruded polystyrene foam by an extrusion foaming method that comprises extruding a foamable polymer mixture through a die and allowing the foamable polymer mixture to expand into a single polymer foam having a width of 750 millimeters or more, the foamable polymer mixture characterized by comprising a styrene polymer and a blowing agent package comprising carbon dioxide at a concentration of 2.0 weight percent or more and 3.0 weight percent or less of carbon dioxide based on styrene polymer weight and by being free of halogenated blowing agents;
• and
• (b) milling a primary surface of the extruded polystyrene foam;
• where the extruded polystyrene foam is further characterized by having a ρ(CST/CSP) value that is 50 kilograms per cubic meter or less where ρ corresponds to the extruded polystyrene foam density, CST corresponds to compressive strength of the foam in its thickness dimension and CSP corresponds to compressive strength of the foam in a dimension perpendicular to the thickness dimension of the foam.