Water Absorptiveness Tester (Cobb Tester) – Essential for Paper & Packaging Quality Control

A Water Absorptiveness Tester, also known as a Cobb Tester, is a precision instrument used to evaluate the moisture absorbency of paper, cardboard, and other fibrous materials. Since water absorption affects the durability and performance of paper-based products, Cobb testing plays a vital role in quality control and product development across various industries.

How the Cobb Test Works

The Cobb test measures the amount of liquid absorbed by a material over a specified period. A 100 cm² specimen is securely placed in the testing device, and a controlled volume of water (or other liquid, such as oil) is poured onto the surface. After a set time, the excess liquid is drained, and the sample is weighed before and after the test. The difference in weight is used to calculate the water absorption rate of the material.

Industry Standards for Water Absorptiveness Testing

To ensure accuracy and consistency, the Cobb Test adheres to internationally recognized standards:

• ISO 535 – Water absorptiveness of paper and board.
• ASTM D3285 – Water absorptiveness of corrugated and solid fiberboard.
• TAPPI T441 – Cobb test for paper and paperboard.
• GB/T 1540 – Standard test for water absorption of paper and board in China.
• JIS P8140 – Japanese Industrial Standard for measuring water absorption in paper and board.

Applications of the Cobb Tester

The Cobb test is essential in industries where water resistance and liquid absorption are critical, including:

• Packaging Industry – Ensures that cartons, boxes, and corrugated materials maintain their strength when exposed to moisture.
• Printing & Publishing – Evaluates the water absorbency of paper to ensure optimal ink adhesion and print quality.
• Tissue & Specialty Paper Manufacturing – Determines the moisture retention of products like filter paper, tissue paper, and coated boards.
• Food & Beverage Packaging – Ensures that paper-based food packaging materials provide adequate protection against moisture and grease.

Qualitest’s Cobb Tester – Reliable & Accurate Results

Qualitest offers advanced Water Absorptiveness Testers designed for precise and repeatable measurements of water, oil, and liquid absorption in paper and board materials. Our Cobb Testers ensure full compliance with ISO, ASTM, TAPPI, GB/T, and JIS standards, making them an ideal choice for quality control, research, and manufacturing applications.