Overview
ISO 105‑Z07:1995 - Textiles - Tests for colour fastness - Part Z07: Determination of application solubility and solution stability of water‑soluble dyes - defines a practical laboratory method to determine the application solubility of water‑soluble dyes (typically between 40 °C and 90 °C) and to assess their solution stability. The method identifies the concentration at which dye residues appear on a heated, pre‑warmed Nutsch (Büchner) filter and uses visual assessment and flow‑through time as evaluation criteria. It is explicitly not intended to measure absolute solubility.
Key topics and technical requirements
- Scope: Determination of application solubility limits and short‑term solution stability of water‑soluble dyes; typical test temperature is 90 °C but lower temperatures may be used per manufacturer guidance.
- Principle: Prepare a series of dye solutions of known concentration, heat with stirring, filter at the test temperature, and evaluate filter residues and flow‑through time.
- Apparatus and reagents: includes wide‑mouthed Erlenmeyer (500 ml), thermostatically controlled heating bath with magnetic stirrer (500–600 r/min), heatable Nutsch filter (≈70 mm ID), vacuum apparatus (3–4 kPa during filtration), circular filter papers (70 mm ±2 mm), and grade 3 laboratory water (ISO 3696).
- Procedure highlights:
- Preheat filter and equipment to test temperature to avoid thermal shock.
- Stir solutions for specified times (e.g., total ~10 min when preparing at 90 °C) before immediate filtration.
- For solution stability, store prepared solution at the storage temperature for 2 hours, mix and then filter.
- Evaluate visually for residues; use sudden increases in flow‑through time as an additional indicator of exceeded solubility or instability.
- Test reporting: include ISO reference, dye identification, filter type/manufacturer, solubility limit (g/L) with dissolving temperature, solution stability (g/L) with storage/dissolving temperatures, flow‑through times, observations and any deviations.
Applications and users
- Who uses it: textile dye manufacturers, dye formulators, quality control and testing laboratories, textile chemists, and compliance officers concerned with dye application performance and process control.
- Practical uses:
- Verify suitable dye concentrations and application temperatures for manufacturing recipes.
- Screen dyes for process stability (preventing precipitation during storage or heating).
- Support troubleshooting of dyeing process issues related to undissolved residues, filtration problems, or inconsistent colour delivery.
- Provide documented solubility limits for quality specifications and supplier declarations.
Related standards
- ISO 105 series (colour fastness tests) - general context for textile dye testing.
- ISO 1773 (laboratory glassware - boiling flasks) and ISO 3696 (water for analytical laboratory use) referenced for apparatus and reagents.
Keywords: ISO 105‑Z07, textiles, colour fastness, water‑soluble dyes, dye solubility, solution stability, application solubility, Nutsch filter, dye testing, ISO 105.