Barrier Performance
Quantifiable resistance metrics for grease penetration determine the suitability of paper and board for packaging oily or fatty food products. The kit test tappi t 559 measures the ability of a surface to resist the penetration of a series of reagents with decreasing surface tension. It is commonly used to evaluate the effectiveness of greaseproof coatings or fluorochemical treatments.
Fluid Penetration
The procedure involves applying a drop of a specific oil and solvent mixture to the surface of the substrate for fifteen seconds. Each mixture in the series is assigned a number from one to twelve where higher numbers represent more aggressive fluids. A failure is recorded if the liquid darkens the paper or leaves a visible mark after the drop is wiped away.
The highest number that does not penetrate the surface becomes the kit rating for that material. Smoothness and porosity of the paper can influence the rate at which the fluid interacts with the fibers. Modern water based barriers are often tested this way to ensure they provide a sufficient shield against grease migration.
Grade Assessment
Testing multiple areas of the sheet provides a representative average of the barrier performance. Different food applications require different kit levels to prevent the staining of the outer package. The standard establishes a numerical scale for the comparison of different board grades.
It provides a quick and cost effective method for quality control during the manufacturing process.
