TAPPI T538

Introducing TAPPI T538 – Industrial Physics

TAPPI T538 is the industry‑standard method for measuring the roughness of paper and paperboard using the Sheffield airflow method. This test evaluates how air flows between the sample surface and a pressurised measuring head, providing a sensitive indication of surface smoothness. Because surface texture directly affects printability, coating behaviour, friction, and appearance, Sheffield roughness is a key quality metric for many paper grades.

What TAPPI T538 Covers

TAPPI T538 defines a controlled procedure for determining Sheffield roughness by measuring the rate of air leakage between the paper surface and two concentric annular lands. Key elements include:

• Backing the sample with flat glass
• Applying a pressurised measuring head with concentric annular lands
• Measuring airflow between the sample and the metal lands
• Reporting roughness in Sheffield units, where higher values indicate rougher surfaces

The method applies to:

• Printing and writing papers
• Packaging grades
• Coated and uncoated papers
• Paperboard requiring controlled surface texture

The airflow rate is directly related to surface undulations and imperfections.

Where TAPPI T538 Is Used

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

• Paper mills and coating operations
• Printing and converting facilities
• Quality‑control laboratories
• R&D and formulation teams
• Certification and compliance testing

It supports both routine production monitoring and comparative evaluation of surface quality.

Why Surface‑Roughness Testing Matters

Understanding Sheffield roughness is essential for:

• Ensuring printability and ink laydown
• Optimising coating absorption and uniformity
• Controlling friction and handling behaviour
• Maintaining consistent appearance and gloss
• Meeting industry and customer specifications

Surface roughness influences how paper performs in high‑speed printing, converting, and finishing operations.

Testing solutions for TAPPI T538

Three products from the Featured Products section align with TAPPI T538’s focus on surface‑texture and airflow‑based measurement:

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 T538.

Your Global Test and Measurement Partner for TAPPI T538

Industrial Physics supports paper manufacturers, converters, and laboratories with the tools and expertise needed to evaluate surface performance in line with TAPPI T538. From Sheffield roughness testing to full physical‑property analysis, we help ensure your materials meet demanding print and performance standards.