Significance & Process of Cob Testing

When it comes to determining if the paper or packaging material is strong enough to resist excess water, manufacturers prefer a cob test. Performed using a cob sizing tester, the cob test determines the quantity of water absorbed by the paper or board in a specific time and under given conditions. 

This test explains a lot about the paper, including of course its water-absorptive capacity, characteristics, durability, porosity, etc.

Significance of Cob Test

Paper is a hygroscopic material, which is why it can attract a lot of water or moisture from the surroundings. This is the reason to perform a cob test. This test helps manufacturers know the water resistance capacity of paper/board. In other words, it helps them know if the paper or board box will be able to maintain its integrity and strength if exposed to moisture or wet conditions.

If the paper absorbs too much water, it indicates that the box lacks strength and integrity and won’t be able to protect the products inside for long. This ability is defined by the cob value that is determined after performing the test on the cob sizing tester. 

A high cob value tells that the paperboard can absorb and retain moisture, while a low cob value indicates that it resists water absorption and retention. Manufacturers use this value to manufacture the right kind and quality of the paper. 

Process of Cob Test

During the cob test, the operator places the sample between the sliding pad and the pivotal cylinder and then tightens it using the screw. He then adds 100 ml of water into the cylinder and turns it down. The self-starting digital timer starts recording the absorption time automatically. Once the test completes, the operator empties the cylinder, takes out the specimen, and then removes excess water using a couch roller. He then weighs the sample on the digital weighing machine. 

He then calculates the cob value by subtracting the weight of the sample before the test from that after the test.

Conclusion

A cob test is as important as any other quality measurement test of paper. Manufacturers use many paper and package testing equipments to evaluate the properties of materials and provide customers with the best quality. If you’re looking for those reliable machines at the best prices, visit UEC.