It is an instrument used to determine the amount of liquid a material absorbs. Materials should be paper, cardboard, corrugated fibreboard or paperboard. If the paper has a high Cobb value then it indicates the ability of the material to retain moisture. Hence, to prevent moisture, the Cobb value of the materials should be maintained. So for this purpose, users use a Cobb tester. A Cobb test measures the amount of water absorbed by the paper at a specific time.
In a Cobb tester, a metal ring is placed which holds the sample and after it, the ring is placed in water for a specific period.
After the completion of the process, the quality of materials and moisture is evaluated by a Cobb tester.
What is the purpose of Cobb?
There is a main role of the Cobb sizing tester in determining moisture. It determines the amount of liquid absorbed by the paper, paperboard or corrugated fireboard. It determines the Cobb value in a given period under some conditions.
How do you test Cobb’s value?
For testing the Cobb value, follow these steps.
Cut the sample in a circular shape.
Weight the sample.
Place the sample in a test area and fill the area with water as a test requirement.
Wait for some time and then rinse with extra water.
After that, take the sample out from the area and extract the water with the help of a roller.
Now, subtract the wet weight from the dry weight.
The remaining value is the Cobb value of a paper.
This value is the amount of water absorbed by the paper in the meantime.
What is the Cobb value of packaging materials?
The Cobb value of packaging material measures the absorbance of liquids. This value tells the amount of liquid absorbed by the packaged material in the meantime. However, the unit for Cobb value is usually expressed in grams per square meter.
Moreover, this Cobb value needs to be maintained to keep up the quality of packaging materials. Hence, the materials go through a Cobb tester to determine the Cobb value of a material.
What is the formula for Cobb testing?
In a Cobb test, the sample is weighed and placed in the area and after that some amount of water is poured on the sample and the sample absorbs the water. After that the excess water is removed and the weight of the wet sample is calculated. After that, the weight of the dry sample is abstracted from the wet sample.
The formula used in Cobb testing is:
Cobb Value= Weight of the sample absorbed/ area of the sample.
What is Cobb’s value unit?
The unit of Cobb value is grams per square meter (g/m²).
This unit tells the amount of water absorbed by the packaging.