Disclosed is a method to inhibit the formation of a paint-product skin on the interior surface of the lid of a closed upright vessel housing a paint composition wherein a portion of said composition is volatile. The method comprises delivering said paint composition to an upright, open vessel closeable at its top with a lid; delivering a sufficient quantity of a barrier material to the open vessel to provide a covering layer of the barrier material for the top of the paint composition; and closing the open vessel at its top with a lid. The barrier material is characterized as (1) less dense than the paint composition; (2) containing a volatile portion whose volatility is at least substantially equivalent to the volatility of the volatile portion of the paint composition; and (3) sufficiently compatible with the paint composition to become a mixed non-detrimental component thereof upon adequate mixing therewith.