Wet strength of paper and cardboard according to ISO 3781 | Tappi T456
ISO 3781 and TAPPI T456 (used primarily by the North American paper industry) define the tensile test used to determine the wet strength of paper or cardboard, after it has been water-soaked for a specified period of time.
The wet tensile strength is the maximum tensile force per unit of width that a water-soaked specimen can withstand before it breaks in the tensile test. If paper is used or processed in a wet state, wet strength is one of its most important material properties.
In principle, the method can be used for both paper and cardboard, but not for sanitary papers and tissues, which exhibit low strength when wet. The wet tensile strength of tissue is defined in ISO 12625-5.
Specimen preparation and test equipment Testing machines Downloads Request a consultation
Specimen preparation, test method and test equipment to determine the wet strength of paper
Specimen preparation:
- The prepared paper strips must be immersed in distilled water until saturated (approx. 1 hour).
- Cardboard and other heavily sized paper may require a longer immersion time to achieve a satisfactory degree of saturation.
- With highly absorbent paper it may be advantageous to, to soak only the middle section, so that the sections of the specimen that are gripped remain dry.
After immersion, the samples must be lightly blotted and then immediately tested as defined by ISO 1924-2/3.
Test equipment:
The strength of the paper material determines which materials testing machine to use. However, most paper tensile tests require much less than 5 kN, making a single-column zwickiLine universal testing machine a good choice.
As per the standard, pneumatic grips are the preferred clamping solution for paper testing. The pneumatic gripping pressure can be easily adjusted to prevent specimen damage and slippage. Alternatively, our screw grips, which can also be adjusted manually with precision, are suitable.
Our testXpert testing software is user-friendly and customizable. It provides all the necessary calculations and statistics for tests performed according these paper standards, including tensile energy absorption (TEA). In many cases the only result to be determined is the tear strength or tear length, superfluous results can be hidden by the software. The testXpert testing software accomplishes this by means of two functional levels.
- Standard test programs (to ISO 1924-2, ISO 1924-3, ASTM D828 or TAPPI T494) contain only test sequences and test results which are stipulated in test standards.
- Changing to Master functionality provides access to all the program's capabilities, ensuring the necessary functional scope for future tests.
If required, change in length and width can be measured directly with videoXtens.
