COBB 30-60 Water Absorption Test of Cardboard or Corrugated Board

The COBB value defines the water absorption capacity of the cardboard or corrugated board. This value provides information about the water absorption capacity of these materials. The COBB test is performed to determine the amount of water taken up by a given sample area through unilateral contact with water over a given period of time. In general, contact times of 30, 60, 180 and 1800 seconds are applied, depending on the material. To achieve certain COBB values, the carton must be sized. During testing, additives called sizing agents are added through mass sizing or surface sizing, which causes partial water escape (hydrophobization).

Water absorbency (COBB value) refers to the mass of water absorbed by 1 square meter of paper, cardboard or corrugated cardboard under 1 cm of water in a certain period of time.

These tests are mainly carried out in accordance with the following standard: EN ISO 535 Paper and cardboard - Determination of water absorbency - COBB method. This standard describes a test method for determining the water absorbency of sized paper and board, including corrugated board, under standard conditions. This method is not suitable for paper weighing less than 50 g/m2 or embossed paper. It is also not suitable for porous papers such as newsprint or unsized papers such as blotter paper and other papers with relatively high water absorbency.

COBB tests are performed because materials such as paper, cardboard and corrugated board tend to attract and retain water molecules from the surrounding environment. These tests are important as they determine the ability of these materials to resist water penetration and the amount of water absorbed. If too much water is absorbed, products made with these materials have difficulty maintaining strength and integrity. This creates a problem for packages containing dangerous or valuable goods.

For packaging exposed to high humidity levels, it is better to use cardboard or corrugated cardboard with a low COBB value. The lower the COBB value (lower water absorption capacity), the more stable the package will be even at high humidity.

Our organization also provides testing services to determine the water absorbency of COBB 30/60 cardboard or corrugated cardboard, with its trained and expert staff and advanced technological equipment, among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors.