COBB Tester Video Guide by PackTest.com (Confirms to : TAPPI T441 / ASTM D 3285 / ISO 535)

Summary

This video guides viewers through the process of conducting a Cobb test for measuring water absorption in materials. The procedure includes preparing the sample by cutting a disc shape, weighing it, and submerging it in demineralized water. After waiting for the designated time, the sample is removed, blotted, and weighed again. The test's outcome is calculated by determining the weight difference and using a formula. The video emphasizes the importance of using fresh water for each test and cleaning the testing equipment after every use.

Takeaways

• 😀 Measure the initial weight of the sample with 0.01 grams accuracy before beginning the test.
• 😀 Cut a disc shape from the paper sample, using scissors. Precision is not critical for this step.
• 😀 Use 100 ml of demineralized water in the well or bowl of the cob tester for the test.
• 😀 Ensure the sample is placed with the test side down (usually the glossy or printed side).
• 😀 Secure the sample by placing the lid on top and tightening the screw knob.
• 😀 Turn the testing station upside down using the handle and wait for 50 to 110 seconds.
• 😀 Rotate the handle back to the original position after waiting for the specified time.
• 😀 Carefully remove the sample from the machine after loosening the screw.
• 😀 Place the wet side of the sample between two sheets of blotting paper and roll a 10 kg roller over it twice.
• 😀 Reweigh the sample after blotting, and record the final weight.
• 😀 Calculate the cob value using the formula: Cup = (final weight - initial weight) * 100.
• 😀 After each test, discard the used water and clean the bowl with tissue paper. Always use fresh water for subsequent tests.

Q & A

What is the first step in the process described in the script?

The first step is to take a sheet of paper and unscrew the lid, then remove it from the machine.

How is the sample prepared for testing?

The sample is placed on the machine, and a circle is marked on it with a pen. A scissor is then used to cut the disc shape, though accuracy is not essential.

What is the importance of measuring the sample's initial weight?

Measuring the initial weight is crucial as it serves as a reference for calculating the water absorption rate after the test.

What is the role of the demineralized water in the process?

The demineralized water is poured into the well or bowl of the cob tester to ensure a consistent test environment for measuring water absorption.

How is the sample positioned for testing?

The sample is placed with the test side down on top of the well or bowl, with the test side typically being the glossy or printed side.

What happens after the sample is placed in the tester?

The lid is placed on top of the sample, and the screw knob is tightened to hold the sample firmly in place before turning the testing station upside down.

What is the duration of the waiting period during the test?

The sample must be left in the upside-down position for 50 to 110 seconds before rotating the handle to return the testing station to its original position.

What should be done with the sample after removing it from the tester?

After the sample is removed, it is placed wet side down between two sheets of blotting paper, and a 10-kilogram roller is rolled twice over the paper.

How is the final weight of the sample determined?

The final weight is determined by reweighing the sample on a digital balance, and this is recorded as the final weight.

How is the water absorption (Cup) calculated?

The water absorption is calculated using the formula: Cup = (Final weight - Initial weight) * 100.

Why is it important to clean the bowl after each test?

The bowl should be cleaned with tissue paper after every test to prevent contamination. Fresh water should be used for every subsequent test to ensure accuracy.

Can this test be applied to other materials besides the sample described?

Yes, the test can also be performed on corrugated board, following the same steps and procedures as for the sample.