Transmission Resistance
A measurable resistance prevents the passage of gases, water vapour, or grease through a packaging material. This property determines how effectively a selected coating or foil layer maintains the original environment of the packaged item. In paperboard packaging, barrier performance determines the shelf life of moisture-sensitive food products by preventing humidity from entering the dry product.
Protective Efficacy
Functional coatings on paperboard are applied to control the migration of external contaminants and internal components. These coatings can consist of synthetic polymers, biopolymers, or mineral layers applied to the paper surface during the converting process. Without such protection, the porous structure of paperboard allows volatile organic compounds from printing inks to migrate into the food.
Substrate Evaluation
Standard evaluation methods measure the volume of gas or liquid that passes through a unit area of paperboard in a specified timeframe under controlled temperature and humidity conditions. Water vapour transmission rate and oxygen transmission rate are the primary values recorded to define the functional limits of a package. These trials ensure that the package complies with food preservation requirements without over-specifying materials, which would increase both cost and weight.
Precise testing of these values allows packaging engineers to optimize coating thickness, ensuring that the physical substrate maintains its structural integrity even in high humidity environments where untreated fibres would quickly soften and fail under load.
