Paper water absorption tester
This article introduces Cobb sizing testers, critical devices for measuring paper and cardboard water absorption rates. By quantifying absorbency, these tools help optimize sizing processes, ensure printability, and evaluate material durability.
Applicable Standards
The tester aligns with key industry standards:
TAPPI: T 441 om-21 (Water Absorptiveness)
ISO: ISO 535 (Paper/board)
GB/T: GB/T 1540 (Paper/board)
Main Parameters
| Parameter | Specification |
|---|---|
| Test Area | 100 cm² (Standard), Adjustable |
| Contact Time | 60/120 seconds (Programmable) |
| Water Volume | 250mL (Standard Reservoir) |
| Measurement Range | 0-500 g/m² |
| Accuracy | ±1% (Full Scale) |
Working Principle
The tester uses a cylindrical head to apply water to a flat sample for a set time. Post-testing, the absorbed water mass is measured and divided by the area to compute the Cobb value (g/m²).
Test Principle
Sample Preparation: Cut a 125mm diameter sample.
Water Application: Place the head on the sample, delivering water for 60/120 seconds.
Result Calculation: Weigh the absorbed water and compute:
Cobb Value = Absorbed Water (g) / Test Area (m²)
Applications
Used in paper mills and QA labs, the tester ensures optimal sizing for printing, packaging, and coating. Compliance with TAPPI/ISO standards ensures reliable data for process control and material development.
This guide equips users with technical insights to select and utilize Cobb sizing testers, ensuring precise absorbency measurement and material quality control.