Smoothness
Also: PPS smoothness, Bendtsen smoothness, Parker Print Surf
The surface regularity of a paper, measured by air leak under a pressurized head (Parker Print Surf, Bendtsen).
Smoothness tests press a metal head against the paper and measure the air that leaks between head and paper at fixed pressure. Rougher papers leak more air. The Parker Print Surf method (ISO 8791-4) is the standard for coated and calendered grades. Bendtsen is a similar test, more common in Europe for uncoated papers.
Smoothness determines printability on offset and gravure presses. A coated woodfree typically targets PPS roughness of 0.8 to 1.2 microns. SC paper runs 1.5 to 2.0 microns. Kraftliner is usually 5.0 microns or higher.
Related
- Calendering. A finishing step where the sheet passes through pressurized roll nips to smooth the surface and control caliper.