Greaseproof and Barrier Stocks for Fills That Defeat Plain Kraft
High-density refining and fluorine-free dispersion coatings block lipid migration and moisture breakdown where unrefined kraft papers fail under aggressive fills.
Grease Resistance ISO 16532-1
Penetration Testing
Standardized laboratory testing determines the time required for a liquid fatty acid mixture to penetrate through a paper or board substrate. Quality control laboratories execute grease resistance ISO 16532-1 to evaluate oil holdout properties of barrier-treated packaging materials. Test specimens sit under specified weights on stained grid paper while standard palm kernel oil reagents contact the top surface.
Visual inspection records the time elapsed before oil stains appear on the underlying grid paper.
Permeation Rate
Surface sizing chemistry and fiber refining intensity dictate the resistance of cellulose networks to fat absorption. Mechanical refining reduces interstitial void spaces between fibers, while surface sizing with starch or synthetic polymers creates a continuous barrier film. Testing under ISO protocols evaluates pinhole defects and surface micro-voids that allow grease transport through the sheet.
Higher resistance times demonstrate superior barrier continuity, essential for fatty food packaging.
Barrier Qualification
Packaging applications for butter, bakery products, pet food, and fast food demand predictable grease resistance performance. Food packaging converters specify minimum holdout duration classes ranging from short term contact to extended storage conditions under elevated temperatures. Testing facilities maintain strict control over temperature and relative humidity during evaluation to obtain reliable, reproducible holdout times.
Substrates failing holdout thresholds permit fatty acid migration through carton walls, resulting in visual staining, structural softening, and premature product degradation. Grease resistance ISO 16532-1 defines the standard testing protocol used across global packaging supply chains to qualify oil-resistant paperboard.