EN 12772 Footwear - Test Methods for Outer Soles - Dimensional Stability

A European standard, “EN 12772 Footwear - Test methods for outsoles - Dimensional stability”, describes a method for determining linear shrinkage after heating of test samples prepared from outsoles.

For the purposes of this standard, dimensional stability is the reduction in the distance between two reference points on a test piece before and after heating in air under specified conditions. This shrinkage is expressed as a percentage of the initial distance.

The following devices and materials are used in the tests:

• Steel ruler marked in millimeters.
• Templates and a scalpel or other sharp blade to cut two reference marks on the test specimen, 100 mm or 50 mm apart.
• Thermostatically controlled oven to heat test samples to 70 degrees plus/minus 2 degrees and to ensure that the required temperature remains within 2 degrees throughout the heating period.
• A device capable of measuring the distance between two cuts on a flat surface, 50 mm or 100 mm apart, with an accuracy of plus or minus 0,2 mm. This device may consist of:
  • A steel ruler marked in millimeters and a x5 magnifying glass, or
  • A portable microscope or similar optical device with a scale.
• Caliper: A caliper that rests on a solid base and is loaded with a dead weight so that the caliper exerts a pressure of 10 kPa plus or minus 3 kPa. This instrument has a flat, circular caliper with a diameter of 10 mm plus or minus 0,1 mm, as defined in ISO 4648. The caliper has a scale division of 0,01 mm.

Test pieces are taken in accordance with EN 13400. All test pieces must be conditioned in accordance with EN 12222 for at least 24 hours before testing. Test samples covering the entire thickness of the outsole must be tested. A minimum of three test pieces are required.

Using a scalpel or other sharp blade and a steel rule, cut test specimens to the dimensions and tolerances shown in the figure. Two parallel reference cuts, spaced no more than 0,5 mm apart across the entire width of the outer surface of the test specimen, are made: 100 mm plus/minus 5 mm for the large specimen and 50 mm plus/minus ±5 mm for the small specimen.

Before heat treatment, the distance between reference cuts along the centerline is measured to the nearest 0,2 mm. For heat treatment, test specimens are placed horizontally in the oven (supported to ensure adequate air circulation on all sides) and held at 70°C (plus/minus 2°C) for 24 hours (plus/minus 0,5 hours).

At the end of the heat treatment period, the test specimen is removed from the furnace. The specimens are held in a standard atmosphere for at least 30 minutes. If the test specimens are curved, they are held straight for measurement. If the measurement cuts are widened, use the measuring point as the center of the cut. The distance between these cuts is measured along the centerline, as described in the figure, using a suitable instrument to the nearest 0,2 mm.

For each test specimen, the shrinkage of the distance between the reference cuts resulting from the heat treatment is calculated and expressed as a percentage of the original distance. The worst of the three values ​​is taken as the result. The shrinkage is calculated in percentage using the formula given in the standard.

In short, the EN 12772 standard includes a test method for assessing the flex resistance of shoe outsoles and their ability to withstand repeated bending without cracking or deterioration. This standard is critical for ensuring the durability and safety of outsoles in various types of footwear, including sports, casual, and work shoes, where flexibility is essential for comfort and performance.

This standard aligns with other footwear standards such as “ISO 20344 Personal protective equipment - Test methods for footwear” and “EN 12770 Footwear - Test methods for outsoles - Abrasion resistance” to provide a comprehensive outsole performance assessment.

The scope of the EN 12772 standard includes:

• Test samples: Outsole materials (e.g. rubber, polyurethane, PVC or leather) as test pieces or entire outsoles.
• Test focus: Resistance to crack initiation and growth under repeated flexing, simulating walking or running conditions.
• Exclusions: Does not cover other properties such as wear (EN 12770) or dimensional stability (EN 12771).

The areas of application of this standard are:

• Quality control: Verification of outsole durability during production.
• Product development: Testing new materials or designs for flexibility and longevity.
• Compliance with legal regulations: Ensuring compliance with EU safety standards, such as personal protective equipment footwear covered by Regulation (EU) 2016/425.
• Consumer safety: Preventing premature outsole failure that could lead to slips or injuries.

As a result, the EN 12772 standard provides a robust, standardized method for assessing outsole flex resistance, ensuring that footwear can withstand the rigors of repeated bending without compromising safety or comfort. By simulating real-world stress, this standard helps manufacturers deliver durable products and meet regulatory requirements. As footwear materials evolve, EN 12772 remains a cornerstone of quality and innovation in outsole design.

Our organization, which has been operating for many years and meticulously follows global developments in science and technology, employs a team of experienced professionals and a broad infrastructure to conduct testing, measurement, and analysis in a wide range of areas for businesses across all sectors. In this context, we also provide testing services in accordance with the EN 12772 Footwear - Test methods for outsoles - Dimensional stability standard.