ISO 20940:2021

Overview

ISO 20940:2021 - Leather - Crust full chrome upper leather - Specifications and test methods - defines requirements, sampling and test procedures for crust full chrome upper leather intended for all types of footwear. The standard targets the leather supply chain (tanneries, laboratories, footwear manufacturers and procurement teams) by specifying physical and chemical characteristics, accepted test methods, and packaging/marking and sampling rules to ensure consistent quality and regulatory compliance.

Key topics and requirements

• Scope: Applies to crust full chrome upper leather (tanned with chromium III, fat-liquored and dried before finishing) used in footwear categories such as town, fashion, sports, cold-weather, school and infants’ footwear.
• Physical characteristics: Specifies required tests and performance parameters for:
  • Tensile strength and percentage elongation (ISO 3376)
  • Tear strength (double-edge tear, ISO 3377-2)
  • Distension of grain and grain crack load (ISO 3379)
  • Colour fastness to rubbing (ISO 11640)
  • Stitch tear resistance (ISO 23910)
  • Water vapour permeability and absorption (ISO 14268, ISO 17229)
  • Flex resistance (ISO 5402-1) Note: Numeric limits depend on footwear type and animal species (bovine, goat, sheep) - consult Table 1 in ISO 20940:2021 for exact values.
• Chemical characteristics: Sets contaminant and composition limits, tested by referenced chemical methods:
  • Chromium (Cr2O3) content minimum (CrIII) - specified (ISO 5398-1)
  • Chromium(VI) content: < 3 mg/kg (ISO 17075-1/2)
  • Limits on chlorinated phenols (total and individual PCP and congeners) (ISO 17070)
  • Formaldehyde ≤ 150 mg/kg (ISO 17226-1)
  • Azo colourants ≤ 30 mg/kg for dyed crusts (ISO 17234-1/2)
  • Soluble matter and pH controls (ISO 4048, ISO 4045)
• Sampling, packaging and marking:
  • Sampling according to ISO 2588; test-piece location per ISO 2418.
  • Packaging must protect leather from humidity, heat and light.
  • Required marking: area, manufacturer ID, lot/month-year and reference to ISO 20940.

Applications and users

ISO 20940 is used by:

• Tanneries producing crust full chrome upper leather for footwear
• Footwear manufacturers and product developers requiring consistent upper-material performance
• Test laboratories performing leather physical/chemical testing and conformity checks
• Procurement, quality assurance and compliance teams verifying supplier material meets footwear performance and safety expectations
• Regulators and standards bodies referencing accepted methods for leather safety (e.g., chromium VI limits)

Related standards

ISO 20940 references and aligns with many leather test standards, including ISO 3376, 3377-2, 3379, 5402-1, 11640, 14268, 17075, 17226, 17234, 17070, ISO 2418 and ISO 2588. These are essential for full implementation of the test methods and sampling procedures.

Keywords: ISO 20940:2021, crust full chrome upper leather, leather testing, footwear upper specifications, chromium VI, leather standards, tanneries, quality control.