Synthetic Leather Tear Strength Testing: Methods, Standards, and Applications

Tear strength determination is one of the most important mechanical evaluations for synthetic leather, quantifying how well polyurethane (PU) or polyvinyl chloride (PVC) coated materials resist tear initiation and propagation during cutting, stitching, and long-term service. This article explains the testing principle, specimen preparation, instrument requirements, calculation methods, and reporting rules for synthetic leather tear strength tests conducted in accordance with recognized GB/T, ISO, and ASTM standards. The results are widely used for quality control, product qualification, and material selection in footwear, upholstery, automotive interiors, luggage, and garment applications.

Technical Overview

Synthetic leather is a composite material consisting of a polymer coating, typically polyurethane or plasticized PVC, bonded to a textile substrate such as woven fabric, knitted fabric, or nonwoven felt. Because finished products are punched with needle holes during stitching, cut into panels, and subjected to repeated flexing and abrasion in service, the material must resist the growth of small cuts and perforations. Tear strength is the property that describes this resistance, and it is expressed either as a tear force in newtons (N) or, in some specifications, as a tear strength per unit thickness in N/mm.

Unlike tensile strength, which measures the force needed to break a uniformly stressed strip, tear testing measures the force required to propagate a deliberately initiated tear through the material. The measured force is governed by the coating elongation, coating adhesion, yarn structure of the substrate, and coating thickness. Since synthetic leather is anisotropic, specimens are normally tested in both the longitudinal (machine) direction and the transverse direction, and the results are reported separately.

Tear testing of synthetic leather is generally performed using one of the following families of methods, depending on the product standard and the end-use specification:

• Trouser tear propagation methods based on GB/T 3917.2 and ISO 13937-2
• Single-edge and double-edge tear methods based on QB/T 2711, ISO 3377-1, and ISO 3377-2, which are also applied to leather-type materials
• Tongue tear methods based on ASTM D751 and ASTM D2261, common for coated fabrics
• Falling-pendulum (Elmendorf) impact tear methods based on GB/T 3917.1, ISO 13937-1, and ASTM D1424
• Product standards such as GB/T 8949 for polyurethane synthetic leather, which specify the applicable tear method and the minimum acceptance values

Testing Samples

Specimen Geometry

For the trouser tear method, a rectangular specimen of 200 mm length and 50 mm width is cut, and a central slit of 100 mm length is introduced from one end along the lengthwise center line, producing two legs of 25 mm width each. For single-edge and double-edge tear methods, rectangular specimens with a predefined cut or central slot are prepared using a sharp cutting die to ensure smooth, parallel edges and a repeatable tear path. For tongue tear methods, the specimen is cut to the dimensions defined by the applicable ASTM method, with two parallel longitudinal cuts forming the tongue wings that are gripped by the jaws.

Sampling and Conditioning

• Specimens are taken at least 50 mm away from the material edges and away from visible defects, seams, or coating irregularities.
• A minimum of three, and preferably five, specimens is tested for each direction (longitudinal and transverse) to ensure statistical validity.
• The direction of each specimen relative to the machine direction of the material is clearly marked before cutting.
• Specimens are conditioned before testing, commonly at 20 °C and 65% relative humidity for textile-based procedures (ISO 139) or 23 °C and 50% relative humidity for leather-type procedures (ISO 2419), for at least 24 hours.
• Thickness is measured at representative points when results are to be normalized to N/mm, using the method referenced by the product standard.

Testing Items

Typical tear-related test items reported for synthetic leather include:

• Trouser tear force (N) in the longitudinal and transverse directions
• Single-edge tear force (N) for slit specimens where one tear front propagates
• Double-edge tear force (N) for slotted specimens where two tear fronts propagate simultaneously
• Tongue tear strength (N), frequently reported as the mean of the highest peak forces recorded during propagation
• Falling-pendulum (Elmendorf) impact tear force, reported in N or mN
• Tear strength normalized by thickness (N/mm) where required by the specification
• Statistical parameters such as the mean, median, standard deviation, and coefficient of variation of all valid specimens

Testing Methods

Trouser Tear Method (GB/T 3917.2 / ISO 13937-2)

The two legs of the slit specimen are clamped in the upper and lower grips of a constant-rate-of-extension (CRE) universal testing machine with an initial grip separation of 100 mm. The jaws separate at a constant rate of 100 mm/min, pulling the legs apart so that the tear propagates along the slit line. The force-extension curve is recorded continuously, producing a typically multi-peak trace as the tear advances through the coating and substrate. The representative tear force is derived from the peak forces within the valid tearing region, using the median or arithmetic mean as prescribed by the standard.

Single-Edge and Double-Edge Tear Methods (QB/T 2711 / ISO 3377 Series)

These methods are widely applied to synthetic leather products specified under leather-oriented standards. The specimen with a predefined cut or slot is mounted in the CRE machine, and the crosshead moves at the constant speed defined by the method until the tear has propagated through the required tear path. The maximum tear force is recorded. In the double-edge configuration, the applied load is carried by two tear fronts, which better reflects the tearing behavior at punched holes and slots in footwear and leathergoods components.

Tongue Tear Methods (ASTM D751 / ASTM D2261)

In tongue tear testing, two cuts are made from one end of the specimen to form a central tongue and two side wings. The tongue is clamped in one grip and the combined wings in the other, and the jaws separate at the rate specified by the method. The tear resistance is determined from the peak forces observed during propagation; in common ASTM practice the reported value is the average of the five highest peaks in the force-extension record.

Falling-Pendulum (Elmendorf) Method (GB/T 3917.1 / ISO 13937-1 / ASTM D1424)

The pendulum method measures the energy absorbed in rapidly tearing a pre-slit specimen and converts it into an average tearing force. Because the deformation rate is far higher than in CRE methods, the result characterizes impact-type tearing, which is relevant to accidental snagging and puncture events during product use. The measured tear energy is reported as a tear force after applying the pendulum capacity factor specified by the instrument and standard.

Data Analysis and Reporting

• The force-measuring system of the testing machine is verified in accordance with ISO 7500-1 or ASTM E4, and the load cell capacity is selected so that measured forces fall within the calibrated working range.
• Multi-peak tear curves are evaluated according to the analytical rules of the governing standard; guidance for evaluating tear curves is also given in ISO 6133 for coated fabrics.
• Specimens that slip in the grips, tear at the grip line, or fail outside the intended tear path are discarded and replaced.
• The final report states the standard used, specimen dimensions, testing direction, conditioning atmosphere, crosshead speed, individual values, and the calculated representative tear force for each direction.
• Results are compared against the acceptance criteria of the applicable product standard, such as GB/T 8949 for polyurethane synthetic leather, or against customer-specific specifications.

Applications

Tear strength data for synthetic leather are used throughout the material supply chain and across many end-use sectors:

• Footwear: qualification of upper, lining, and insole materials where stitching, lasting, and lasting tacks create concentrated tear loads
• Furniture upholstery: verification that seat covers and panels resist tearing at seams, piping, and attachment points
• Automotive interiors: evaluation of seat covers, door trims, and instrument panel coverings against OEM material specifications
• Luggage, handbags, and leathergoods: confirmation of seam and handle durability in cut-and-sew construction
• Garments and gloves: assessment of tear resistance for coated fabrics used in outerwear and protective clothing
• Incoming quality control and supplier audits performed by accredited third-party laboratories
• Research and development: comparison of coating formulations, substrate structures, and lamination processes
• Failure analysis: determination of whether field damage is consistent with insufficient tear resistance or with abnormal service loads

FAQ

What is tear strength in synthetic leather?

Tear strength is the force required to propagate an initiated cut or slit through the coated material. It differs from tensile strength, which measures the force to break an intact strip. Tear strength is the more relevant indicator of durability around stitches, perforations, and punched holes.

Which test method should be selected?

The method is normally dictated by the governing product standard or customer specification. Trouser tear per GB/T 3917.2 or ISO 13937.2 is common for textile-substrate synthetic leather, single- and double-edge tear per QB/T 2711 or ISO 3377 is common for leather-type specifications, and ASTM D751 or ASTM D2261 tongue tear is common where coated-fabric standards are referenced. Results from different methods are not interchangeable.

Why must specimens be tested in both directions?

Synthetic leather is anisotropic because the textile substrate has different yarn or loop configurations along and across the machine direction. Tear force can differ substantially between the longitudinal and transverse directions, so both are measured and reported separately.

Why do tear curves show many peaks, and which value is reported?

As the tear front advances, the coating and yarns deform, resist, and then fail in a stick-slip pattern, generating successive peaks. Standards define whether the median, the mean, or the average of the five highest peaks is reported; the same analytical rule must be applied consistently for all specimens in a comparison.

What are typical acceptance levels?

Acceptance values depend on the product class and are specified in standards such as GB/T 8949 or in customer specifications. Footwear and upholstery grades generally require tear forces on the order of tens of newtons. The applicable product standard or specification should always be consulted for the exact limits.

How are invalid results handled?

Specimens that slip in the grips, tear crookedly outside the intended path, or fail at the grip line are discarded, and additional conditioned specimens from the same sample are tested until the required number of valid results is obtained. The number of discarded specimens is noted in the report.