Overview
EN ISO 105‑Z08:1997 (ISO 105‑Z08:1995) specifies a laboratory method to determine the solubility and solution stability of reactive dyes in the presence of electrolytes. The procedure is intended to simulate conditions encountered in both batchwise and continuous dyeing processes and helps define dye behaviour when common electrolytes (e.g. sodium chloride, sodium sulfate, sodium carbonate, sodium hydroxide, urea, sodium silicate) are added. Results are reported as solubility and stability limits (grams per litre) and by visual and flow‑through filtration criteria.
Key topics and technical requirements
- Scope: Tests the dye solution’s ability to remain dissolved and stable after electrolyte addition under specified temperatures and times.
- Test principle: Prepare a series of dye solutions at known concentrations, add a defined volume/concentration of electrolyte, store or filter at specified temperatures, then assess filter residues and filtrate flow time.
- Apparatus & reagents: wide‑mouthed Erlenmeyer flask, thermostatic heating/water baths, heatable Nutsch (Büchner) filter, vacuum pump, stopwatch, 70 mm filter paper and grade‑3 water (ISO 3696). Chemically pure electrolyte reagents are recommended for reproducibility.
- Procedure highlights:
- Predissolve dye at a set temperature, homogenize and adjust to test temperature.
- Add stock electrolyte solution and allow storage for specified time (examples provided for batch and continuous processes).
- Filter at test temperature, measure flow‑through time and examine dried filter papers for residues.
- Evaluation & reporting: Visual detection of residues (or fingertip rubbing), sudden increases in flow‑through time, and numerical reporting of solubility/stability limits, test temperatures, electrolyte identity/concentration, filter paper type and any deviations.
Practical applications and users
- Quality control laboratories assessing dye suitability for commercial dyeing operations.
- Dye manufacturers and R&D teams screening reactive dyes for sensitivity to electrolytes.
- Textile mills and process engineers optimizing batch or continuous dyeing recipes to avoid precipitation or instability.
- Certification and testing bodies performing comparative or compliance testing related to colour fastness and dye performance.
Factors affecting results
Annex A notes sources of variability: electrolyte purity and ageing, filter quality, dissolving/storage temperatures, storage time and composition of dyebath simulants. Fresh electrolyte solutions and standardized materials improve reproducibility.
Related standards
- ISO 3696 - Water for analytical laboratory use
- ISO 1773 - Laboratory glassware (boiling flasks reference)
- ISO 105 series (see ISO 105‑A01 for Part listing)
Keywords: EN ISO 105‑Z08, reactive dyes, solubility, solution stability, electrolytes, dyeing processes, colour fastness, textile testing.