ISO 5433:2022

Overview

ISO 5433:2022 - Leather - Bovine wet blue - Specification defines requirements, sampling and test methods for bovine wet blue leather tanned primarily with basic chromium sulfate. This third edition (2022) replaces ISO 5433:2013 and provides standardized criteria for raw material, tanning, presentation, chemical limits, shrinkage temperature, fungicide use, sampling, testing, packaging and marking of wet blue bovine hides and parts.

Key topics and technical requirements

• Tanning: Must use basic chromium sulfate as the primary tanning agent; visual inspection shall show complete penetration by the bluish chromium color. Tanning carried out at pH ≥ 3.0.
• Shrinkage temperature: Measured per ISO 3380. Minimums: ≥ 85 °C for low chrome tannage and ≥ 100 °C for full chrome tannage. Chromic oxide content guidance links to these requirements.
• Chemical requirements (Table 2):
  • Volatile matter: > 50% of dry mass (or as agreed)
  • Matter soluble in dichloromethane: < 2% of dry mass (or as agreed)
  • pH of water extract: ≥ 3.2
• Fungicidal additives: Fungicides should inhibit mould and pigmentation, be non-hazardous, and doses agreed between purchaser and supplier; recommended protection for storage up to 4 months under prevailing conditions.
• Presentation and appearance: Grain side free from hair; preferably tight grain with no creases or iron-stain; at least 95% of pieces in a lot should be free from chromium salt stains, with any stained area per piece not exceeding 10% of total area.
• Sampling & dispute resolution: Routine sampling agreed between parties; dispute sampling quantities specified (e.g., up to 100 skins → 3 samples; 701+ → 7 samples) and locations per ISO 2418.
• Packaging and marking: Packages must preserve original wet condition; labels to include material type, manufacturer, tanning month/year, number of skins and purchaser-required details.

Applications

ISO 5433:2022 is used for:

• Quality control and acceptance criteria in leather manufacturing and tannery operations.
• Procurement specifications for buyers and traders of bovine wet blue leather.
• Laboratory testing and certification for compliance with industry standards.
• Contractual dispute resolution where standardized sampling and testing are required.
• Logistics and storage planning to ensure product stability and antifungal protection.

Who should use this standard

• Tannery managers and production engineers
• Quality assurance and laboratory personnel (physical/chemical testing)
• Leather traders, buyers, importers/exporters
• Standards and compliance officers in the leather value chain

Related standards

Normative references used by ISO 5433:2022 include: ISO 2418, ISO 3380, ISO 4044, ISO 4045, ISO 4048, ISO 4684, ASTM D4576 and ISO 5398-1 for chromic oxide determination. These are essential for implementing the specified test and sampling methods.