IGT Pick & Blister (Westvaco Rod Applicator)

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This test measures the ability of coated or uncoated paper or paperboard to resist picking or blistering during offset printing. The test device operates by metering a 15μm film thickness of polybutyne oil of a given viscosity onto the surface of a steel roll with a Westvaco Rod Applicator. The oil is transferred to the surface of the substrate while under acceleration (i.e., the speed increases from 0 m/s to 4 m/s during application). The oil creates a pulling action on the paper surface, like offset ink, resulting in picking, blistering, or both. The point at which the picking and blistering starts is the end point of the test. The reported units for both pick and blister are viscosity-velocity product (vvp). At a known oil viscosity, this indicates the velocity or press speed that can be achieved before the sheet is damaged.