TAPPI T536

Introducing TAPPI T536 – Industrial Physics

TAPPI T536 is the industry‑standard method for measuring the air resistance of paper using the high‑pressure Gurley method. This test evaluates how long it takes a fixed volume of air to pass through a 1 sq. in. circular area of paper under a pressure differential of approximately 3 kPa. It is widely used for papers where air permeability affects performance, such as packaging grades, filter papers, and specialty technical papers.

What TAPPI T536 Covers

TAPPI T536 defines a controlled procedure for determining air resistance using a high‑pressure Gurley densometer. Key elements include:

• Testing a 6.4 cm² (1 sq. in.) circular sample
• Applying a 3 kPa pressure differential
• Measuring the time required for 10 mL of air to pass through the sheet
• Using automatic or manual timing devices
• Reporting results in Gurley seconds

The method applies to:

• Papers requiring 10 seconds or more for 10 mL of air to pass through
• Packaging papers
• Specialty papers
• Papers where porosity, density, and fibre bonding influence performance

The method is not suitable for very permeable papers or papers with rough surfaces that cannot be clamped securely without leakage.

Where TAPPI T536 Is Used

This method is widely used across the paper and packaging supply chain, including:

• Paper mills and coating operations
• Packaging‑material manufacturers
• Filter‑paper producers
• Quality‑control laboratories
• R&D and formulation teams
• Certification and compliance testing

It supports both routine production monitoring and comparative evaluation of air‑permeability performance.

Why Air‑Resistance Testing Matters

Understanding air resistance is essential for:

• Ensuring barrier performance in packaging
• Evaluating fibre bonding, refining, and sheet density
• Predicting printability and coating holdout
• Assessing filter performance
• Meeting industry and customer specifications

Air resistance is a key physical property used alongside porosity, basis weight, thickness, and density to characterise paper structure.

Testing solutions for TAPPI T536

Three products from the Featured Products section align with TAPPI T536’s focus on paper‑structure and performance evaluation:

Profile Plus Bendtsen Roughness with Porosity A high‑precision module designed for Bendtsen roughness and porosity testing, offering controlled airflow measurement ideal for evaluating surface smoothness and structural uniformity in paper and board.

Profile Plus Porosity A dedicated porosity‑measurement system that provides accurate airflow‑based evaluation of paper structure, supporting roughness‑related analysis and complementing Sheffield‑method testing.

Sheffield Porosimeter A specialised instrument for Sheffield roughness testing, delivering precise airflow‑based surface‑smoothness measurements in full compliance with TAPPI T536.

Your Global Test and Measurement Partner for TAPPI T536

Industrial Physics supports paper manufacturers, converters, and laboratories with the tools and expertise needed to evaluate air‑resistance performance in line with TAPPI T536. From Gurley densometers to full physical‑property analysis, we help ensure your materials meet demanding performance and quality standards.