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ISO 535 Water Absorptiveness Testing

ISO 535 package testing determines the water absorptiveness of paper and board. As an ISTA and ISO 17025 certified lab, we realize the importance of ISO 535 testing. Meeting the ISO 535 water absorptiveness testing requirements can be difficult. We understand the challenges and guide companies through the process.

Keystone Package Testing partners with customers to achieve package compliance. Our accurate test reports are delivered quickly. We create an accurate test plan to eliminate expensive over-testing. Keystone takes a consultative approach throughout the entire test program.

Request a quote to receive testing services customized to your specific needs. Contact us to receive more information on ISO 535 standard conditioning test.

Summary of Paper and Board Water Absorptiveness – Cobb Method

The purpose of the ISO 535 method is to determine the water absorptiveness of sized paper and board. This Cobb testing method also includes corrugated fibreboard under standard conditions. It may not be suitable for paper of grammage less than 50 g/㎡ or embossed paper.

Water Absorptiveness (Cobb Value): The calculated mass of water absorbed in a specified time by 1 m2 of paper or board under specified conditions.

A test piece is weighed immediately before and immediately after exposure for a specified time of one surface to the water, followed by blotting. The result shows an increased mass expressed in grams per square meter.

Note that the standard gives a general indication for use with aqueous solutions. However, this method is not intended to be used for precise evaluation of the writing properties of paper.

Scope of ISO 535 Water Absorptiveness Testing

Both surfaces that come into contact with the test piece are dried before commencing each test. The test pieces are weighed to the nearest milligram. Then, they are placed to be tested with the uppermost surface on the base plate. This procedure is according to the water absorbency of the paper and board under construction.

At least 10 test pieces of sufficient size are cut from the specimen. It must be ensured that the test area is avoided by contact with hands. Furthermore, the area must be free from visible folds, creases, cracks, or other defects. If watermarks are present, these areas are avoided as well.

Test plates will be rejected if they have been penetrated by the water. They will also be rejected if they show signs of leakage or show excess water after blotting. If no reduced time is fitting, this ISO 535 method is not suitable.

ISO 535 Package Testing Procedures

When mounting the test piece, the upper edge of the surface which will come into contact with the test piece is dried before the start of each test. The cylinder is placed with the machine edge in contact with the test piece and clamped firmly to prevent any leakage of water between it and the test piece.

The time of the test is defined as: The time between when the water first makes contact with the test piece until the start of the blotting. Furthermore, for the purpose of this international standard, the times of the test may be increased according to water absorptiveness and to the special nature of the specimen under consideration.

Significance of ISO 535 Integrity Testing

After the completion of the Cobb Method, a test report will consist of general and in-depth information. Information includes the date, time, location, and specific test engineer. Other information may include but is not limited to, reference to this international standard, the conditioning atmosphere used, and any circumstances or factors that may be affected or influenced by the results.

Expert ISO 535 Paper and Board Package Laboratory Testing

Keystone can accommodate flexible and rigid packages of all sizes, including large pallets. We have a full lab of test equipment which permits us to provide short lead times on scheduling. In addition to ISO 535 testing, Keystone also has a full scope of expertise including sterile barrier, cold chain, and inclined impact.

Are you ready to get started? We are. Contact us and learn first hand why so many companies partner with Keystone to achieve their paper, board, and related product certification needs.

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