ISO 5636-5 permeability test Paper and board — Determination of air permeance (medium range) Part 5: Gurley method

ISO 5636-5:2013 specifies the Gurley method for determining the air permeance of paper and board using an air resistance tester, the Gurley apparatus.

It is applicable to papers and boards which have air permeances between 0,1 µm/(Pa⋅s) and 100 µm/(Pa⋅s) when tested with the Gurley apparatus.

It is unsuitable for rough-surfaced materials, which cannot be securely clamped to avoid leakage.

ISO 5636-5:2013 may also be used to determine the air resistance of paper and board.

Principles of operation of the Gurley Densitometer

The Gurley densitometer is a precision instrument designed to measure the time it takes for a specific volume of air (100 cm³) to pass through a defined surface (1.0 in²) of a paper sample under a certain pressure (1.2 kPa). This measurement is essential for determining the resistance and quality of paper in various packaging applications.

Standardized test protocol for paper air permeability

For reliable results, it is imperative to follow a standardized test protocol. Test samples must be conditioned at a temperature of 23±1°C and a relative humidity of 50±2%, in accordance with ISO 187 standards. The sample preparation directly influences result accuracy.

Calculation and interpretation of results

The air resistance of the sample is calculated by dividing the recorded time by the sample's surface area. This result, expressed in seconds per 100 milliliters [s/(100 ml)], indicates the paper's air permeability. Air permeance is then calculated by dividing the unit pressure by the product of air resistance and air density, expressed in micrometers per second pascal [μm/(Pa⋅s)]. These measurements provide valuable insights into paper quality and durability.