TAPPI T441 Cobb Test

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:

TAPPI T441 – Water Absorptiveness of Sized (Non-Bibulous) Paper, Paperboard, and Corrugated Fiberboard (Cobb Test). The amount of moisture in paper affects the overall physical strength, porosity, and printability. This method can be ideal when evaluating different surface coatings applied to the material for increased performance in addition to verification of resistance to water absorption requirements, which are common for some regulated packaging. Depending on the material, the test’s duration is between one and thirty minutes and measures the amount of water absorbed by weight.

Key Points:

Related Standards:

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