How to Perform Cobb Sizing Test Using Varied Liquids

A paper has to go through multiple environments and conditions in its life. During this span, while it comes across solids, it also accidentally gets in contact with liquids. These liquids can be water, chemicals, oil, and like that. The water absorptiveness of the paper determines the ability of the paper to absorb such liquids. And the Cobb size test is performed to determine the paper’s ability to absorb and resist the absorption of these liquids.

Conducted using the Cobb sizing tester, in the Cobb test, the user measures the quantity of water absorbed by the paper in a specific time and under standardized conditions. Other liquids like ink, oil, beverages, etc. can also be used in the test. Papers like newsprint, writing paper, art paper, Kraft liner, corrugated fiberboard, and tissue paper are tested using this tester.  

How is the Cobb Sizing Test performed? 

The Cobb sizing tester is a tilting model which has a clamped lid on its structure. It also comes with a default couch roller and a sliding pad. To perform the test, the specimen is placed along with blotting papers using the roller and pad under the pivoting cylinder. With the unit, is attached a digital timer that automatically starts recording the absorption time as soon as the test begins, and the cylinder is turned down for it.  

The test hardly takes a few seconds to give results, as the test cycle is speedy and accurate in determining the paper’s water absorbency. When the first sheet is tested, the user must place the second sheet of blotting paper on the top of the sample at exactly the completion of the first test period. At this point, he must remove the excess water, ink, oil, etc., using the roller. The roller is first moved forward and then back over the sliding pad to remove the liquid. 

Subtract the weight of the paper specimen (taken before the test) from the one taken after the test. Multiply the rise in weight by 100. It will give the weight of liquid absorbed in grams per square meter. This resultant value is called the Cobb value.

End Note

So, this is how the Cobb sizing test is performed using the Cobb tester. UEC is a house of a wide range of paper testing instruments designed to test varied crucial parameters. Visit the website to know about all of them and share inquiries.