Testing Standard:
TAPPI T441 Water Absorptiveness of Sized (Non-Bibulous) Paper, Paperboard, and Corrugated Fiberboard (Cobb Test) ie. TAPPI T441 Cobb Test
Standard Number
TAPPI T441
Standard Title
Water Absorptiveness of Sized (Non-Bibulous) Paper, Paperboard, and Corrugated Fiberboard (Cobb Test), Test Method
Overview for TAPPI T441 Cobb Test:
TAPPI T441 Test Method is used to evaluate the materials rate of water absorption and to verify the performance of any coatings and the sizing applied to the paper. It measures the amount of water that can be absorbed by a given area of the sample after a specified time.
The test involves cutting a circular piece of the sample and placing it on top of an absorbent blotting paper. A specified amount of water is then poured onto the sample and left for a specified amount of time (usually 1 minute). After the time has elapsed, any excess water is removed using a standard roller and the sample is weighed.
The Cobb value is calculated by subtracting the dry weight of the sample from the weight of the wet sample, then dividing by the area of the circular sample. The result is reported in units of grams per square meter (g/m²) and is a measure of the water absorption rate of the sample.
The TAPPI T441 Cobb test is widely used in the paper and packaging industries to determine the suitability of paper and paperboard for various applications, such as food packaging, labeling and printing.
Purple Diamond Testing offers TAPPI T441 Water Absorptiveness of Sized (Non-Bibulous) Paper, Paperboard, and Corrugated Fiberboard (Cobb Test) as part of our packaging compliance and validation services.
Rationale for TAPPI T441 Cobb Test:
Key Points:
- Determines the need for moisture barrier coatings and the sizing of paper
- Using this test method verifies compliance with UN DOT regulations
- Utilize this test method to ensure quality control
- Verifies the amount of surface coating used is sufficient
Related Standards:
- ASTM D3285 – Test Method for Water Absorptiveness of Non-Bibulous Paper and Paperboard (Cobb Test)
- ISO 535 – Paper and Board – Determination of Water Absorptiveness – Cobb Method
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