Product Introduction 
The Cobb absorption tester operates on the Cobb method principle. Under specified pressure and temperature conditions, one side of the specimen is brought into contact with water for a defined period. The amount of water absorbed per unit area of the paper or paperboard surface (Cobb value) is determined by measuring the mass change of the specimen before and after water contact, expressed in g/m². Before testing, the specimen is weighed (G1). After the water absorption test under standard conditions, excess surface water is removed with blotting paper, and the specimen is weighed again (G2). The Cobb value is calculated using the formula C = (G2 - G1) × 100. The instrument consists of a 304 stainless steel metal cylinder, a smooth metal roller, and a water reservoir, offering simple operation and reliable data.

Key Features 
All 304 Stainless Steel Construction The entire instrument is manufactured from 304 stainless steel, offering corrosion resistance and rust-free performance, ensuring hygiene and durability over long-term use.
Standard Cobb Method Compliance Designed in full accordance with GB/T 1540-2002 (Paper and board — Determination of water absorption — Cobb method), delivering standardized and comparable test data.
Precision Standard Metal Cylinder Metal cylinder with an internal cross-sectional area of 100±0.2 cm² (inner diameter 112.8±0.2 mm) and height of 50 mm; contact surface is smooth with excellent sealing to ensure accurate test area.
Built-in Water Level Line for Convenient Observation Water level line set inside the reservoir facilitates quick observation and control of water volume, improving operational efficiency and accuracy.
Standard Roller and Blotting Paper Includes a smooth metal roller (width 200±0.5 mm, mass 10±0.5 kg) and blotting paper with a grammage of 200-250 g/m² and absorption rate of 75 mm/10min, meeting standard test requirements.
Compact Structure, Easy Operation Overall dimensions of 390×280×410 mm and weight of 20 kg; benchtop design with a compact structure, intuitive operation, and simple maintenance.
Broad Application Range Suitable for determining the surface water absorbency of various types of paper and paperboard, though not suitable for accurately evaluating the writing performance of paper.
Simple Calculation Formula Cobb value is calculated using the formula C = (G2 - G1) × 100, with clear operation procedures and straightforward result calculation.

Main Technical Specifications 

FAQ 
1. What materials are suitable for the Cobb Absorption Tester?
It is suitable for determining the surface water absorbency of various types of paper and paperboard, including cultural papers, packaging papers, and corrugated boards. However, it is not suitable for accurately evaluating the writing performance of paper.

2. What is the Cobb value calculation formula and its meaning?
The formula is C = (G2 - G1) × 100, where C is the Cobb water absorption value (g/m²), G2 is the specimen mass after water absorption (g), and G1 is the specimen mass before water absorption (g). A lower C value indicates lower surface absorbency and better water resistance.

3. What is the role and specification requirement of blotting paper?
Blotting paper is used to remove excess surface water from the specimen after the water absorption test. The standard requires blotting paper with a grammage of 200-250 g/m² and an absorption rate of 75 mm/10min. When a single layer does not meet the grammage requirement, multiple layers can be stacked.

4. What is the function of the smooth metal roller?
The smooth metal roller, weighing 10±0.5 kg, is used to apply standardized pressure treatment to the specimen before and after the water absorption test. This ensures consistent conditions for surface water removal and guarantees repeatability and comparability of test results.

5. How does the metal cylinder ensure a watertight seal?
The contact surface between the cylinder ring and the specimen is smoothly finished. During testing, the cylinder is firmly pressed against the specimen surface by a clamping device, forming a sealed chamber. This ensures that water contacts only one side of the specimen for the specified duration.

6. Does the instrument require regular maintenance?
The 304 stainless steel construction is corrosion-resistant and rust-free, requiring simple daily maintenance. After use, rinse the metal cylinder and water reservoir with clean water and wipe dry with a soft cloth. Periodically check the sealing surface of the metal cylinder and the surface of the metal roller for scratches or damage.

After-Sales Service 
Established in 2007 and with nearly two decades of experience, Shandong Annimet Instrument Co., Ltd. is a professional manufacturer integrating R&D, production, and sales of laboratory testing and sample preparation equipment. Quality is our foundation. We are your bridge from concept to reality. We deliver more than just instruments — we deliver confidence. This Cobb Absorption Tester comes with a 12-month warranty and lifetime technical support. Our professional team offers 24/7 service response, free installation guidance, operation training, and water absorption testing method consultation. For any inquiries, please contact our customer service team; we are dedicated to providing comprehensive pre-sales, in-sales, and after-sales support. Hotline: 400-9933-057, Email: anmt_test@126.com.