ASTM D3285 Cobb Test

ASTM D3285 is used to evaluate the materials rate of water absorption. This test method applies to most non-bibulous materials, such as paper or paperboard. Purple Diamond Testing offers ASTM D3265 Testing as part of our packaging compliance and validation services. 

The test involves placing a specimen of the paperboard into a shallow tray and adding water to the tray until the water level is above the specimen. The specimen is left in the water for a set period of time, typically 1 minute, and then removed from the tray.

The amount of water absorbed by the paperboard is then measured by weighing the specimen, subtracting the dry weight of the specimen, and reporting the result in grams per square meter (g/m2).

The Cobb test is an important measure of the paperboard’s ability to withstand exposure to water and moisture, which can affect the integrity and strength of the packaging material. It is used to ensure that paperboard meets the requirements of industry standards and regulations, as well as customer specifications for packaging performance.

According to https://www.document-center.com/standards/show/ASTM-D3265, “1.1 This test method covers the determination of the quantity of water absorbed in a specified time by non-bibulous paper and paperboard with a minimum thickness of 0.1 mm. This test method is generally applicable to sized paper and paperboard but is not recommend as a sizing test for writing papers. The test method is based upon studies by Cobb and Loew, Cobb, and other investigators (1,2,3,4).”

The ability to resist the penetration of water in packaging is important, especially if the packaged goods are moving internationally in distribution. If this is the case, there is more time and space for the packaged product to get wet. Thus, the Cobb Test. In particular, the Cobb Test figures out the quantity of water that will be absorbed by the surface of the paper or board each time. Due to various paper and board characteristics, the test of water absorption is a function compared to the sizing and porosity of the paper and board being evaluated. This test is often involved in obtaining certain certifications such as those that involve hazardous materials packaging. The standard method is useful when evaluating a different variety of hygroscopic surfaces that are originally designed to resist water absorption.

Manufacturers, suppliers, and consumers of paper and paperboard products benefit from this test as it provides valuable information about the quality, consistency, and suitability of these products for various applications. The test helps ensure that the paper and paperboard products meet the required standards for their intended use, such as printing, packaging, and labeling. Additionally, the ASTM D3285 Cobb test can be used by researchers and academics to further their understanding of paper and paperboard product development and manufacturing processes.