The zero-span tensile test provides information on the fiber strength of paper and is performed according to TAPPI T 231. A tensile load is applied to a test strip with a grip-to-grip separation approaching zero. This causes most of the load to be applied to the cellulose fibers and less to the total fabric of the paper.
The zero-span tensile test is generally carried out using single-purpose instruments which are correspondingly complex and expensive.
For occasional tests it is worth making use of the modular building block system of specimen grips and supplementary devices.
The exact position of the two specimen grip units relative to each other must first be set (once only) with reference to angular position and horizontal position. A mechanical add-on kit is available for this.
The specimen grips must comply with minimum accuracy requirements, therefore pneumatic grips are needed.
The jaws required protrude upwards from the base of the grips, allowing a free length of around 0.1 mm.