Overview
EN ISO 105-X06:1997 (ISO 105‑X06:1994) specifies a laboratory method for assessing colour fastness to soda boiling for textiles. The procedure evaluates how textile colours resist treatment in boiling dilute sodium carbonate solution, with and without a reduction inhibitor. The test is mainly applicable to natural and regenerated cellulose materials and uses grey-scale assessments to rate both change in colour and staining of adjacent undyed fabrics.
Key topics and requirements
- Specimen preparation: A test specimen (fabric, yarn knitted into fabric, or compressed loose fibre) is sandwiched between specified undyed adjacent fabrics and sewn to form a composite specimen.
- Test assembly: The composite specimen is tightly rolled around a glass rod (5–8 mm diameter) to form a 40 mm cylinder and tied.
- Boiling treatments:
- Boil one specimen under reflux for 1 hour in sodium carbonate solution (10 g anhydrous Na2CO3 per litre).
- Boil the other specimen under the same conditions with the addition of a reduction inhibitor (sodium m‑nitrobenzenesulfonate: 4 g per litre in the solution).
- Typical liquor ratio specified is 30:1.
- Controls and verification: Test controls using a standard Vat Red 1 dyeing (reduced and dyed under defined conditions) are included to validate test performance. If control ratings fall outside expected values, the test must be repeated.
- Assessment: After rinsing and drying, assess colour change and staining using the ISO grey scales (ISO 105‑A02 for change in colour and ISO 105‑A03 for staining). If two adjacent fabrics give different staining ratings, report the lower rating.
- Equipment & reagents: Water-cooled reflux condenser, glass rod, desized undyed cotton (40 × 100 mm), standard adjacent fabrics, specified sodium carbonate and inhibitor solutions.
Applications and users
- Textile manufacturers and dye houses: for quality control of dyeing processes and evaluation of dye classes on cellulosic fibres.
- Textile testing laboratories and standards bodies: for certification, compliance testing and method standardization.
- R&D and formulation teams: to compare dye/binder performance, optimize dyeing processes, and screen reduction inhibitors.
- Purchasing and product compliance teams: to verify durability claims for garments, home textiles and technical textiles made from natural or regenerated cellulose fibres.
Related standards
- ISO 105‑A01: General principles of testing
- ISO 105‑A02: Grey scale for assessing change in colour
- ISO 105‑A03: Grey scale for assessing staining
- ISO 105‑F: Standard adjacent fabrics
Keywords: colour fastness, soda boiling, ISO 105‑X06, textiles, sodium carbonate, reduction inhibitor, sodium m‑nitrobenzenesulfonate, grey scale, colour fastness tests, textile quality control.