Overview
EN ISO 105-E06:2006 - Textiles: Tests for colour fastness - Part E06: Colour fastness to spotting: Alkali (ISO 105-E06:2006) specifies a standardized laboratory method to evaluate how textile colours resist contact with dilute alkaline solutions. The method covers textiles in all forms (fabric, yarn, loose fibre) and provides three test severities so laboratories and manufacturers can choose the appropriate alkali challenge for the fibre type and end‑use.
Key topics and requirements
- Three alkali tests:
- Sodium carbonate solution (Na2CO3) - mild alkaline spotting.
- Calcium hydroxide paste (Ca(OH)2) - moderate severity.
- Ammonium hydroxide solution (NH4OH) - highest severity (specimens steeped for 2 minutes).
- Sample preparation: typical specimen size for fabric is 40 mm × 100 mm. Yarn and loose fibre procedures are also described (knitted fabric specimen or wick; compressed sheet for fibres).
- Application method: spotting with a pipette/dropper and working in with a glass rod for carbonate and hydroxide paste; steeping for ammonium hydroxide. Drying and removal of residues by brushing or rinsing (Grade 3 water) are specified.
- Assessment: colour change is assessed visually using the grey scale (ISO 105‑A02) or instrumentally (ISO 105‑A05). Wet-spot assessment after 10 minutes is included where relevant.
- Reporting: test reports must reference EN ISO 105‑E06:2006 and include sample identification, numerical grey-scale or instrumental ratings for each alkali, wet-change results (if measured), water-spotting resistance (see ISO 105‑E07), and any deviations from the procedure.
- pH guidance: the standard lists typical pH ranges for the reagents (e.g., ammonium hydroxide pH 13.5–13.7; calcium hydroxide pH 12.3–12.5; sodium carbonate pH 11.5–11.7).
Applications
- Quality control for dyed and printed textiles to ensure resistance to alkaline spotting during manufacturing, laundering or end‑use.
- Validation of dye and finishing processes by textile mills, dyehouses and OEMs.
- Routine or acceptance testing in textile testing laboratories and certification bodies.
- Material selection for products exposed to alkaline environments (industrial workwear, medical textiles, household textiles).
Who uses this standard
- Textile manufacturers and converters
- Dyeing and finishing laboratories
- Independent textile test laboratories and certifiers
- R&D teams developing dyes, finishes and colourants
- Quality assurance personnel in apparel, home textile and technical textile sectors
Related standards
- ISO 105‑A01 (general principles)
- ISO 105‑A02 (grey scale for assessing change)
- ISO 105‑A05 (instrumental assessment)
- ISO 105‑E07 (colour fastness to spotting: water)
EN ISO 105‑E06:2006 is essential for consistent, reproducible assessment of alkali-induced colour damage and supports product quality, compliance and material selection in the textile industry.