Overview
EN ISO 105‑Z07:1997 (ISO 105‑Z07:1995) specifies a laboratory method for determining the application solubility and solution stability of water‑soluble dyes used in textiles. The method covers testing in the temperature range 40 °C to 90 °C (application solubility is normally determined at 90 °C but lower temperatures may be used following manufacturer guidance). The procedure is intended to identify practical solubility limits under application conditions - it is not a method for measuring absolute thermodynamic solubility.
Key topics and technical requirements
- Principle: Prepare a series of dye solutions of known concentration, heat and stir at the chosen dissolving temperature, then filter through a preheated heatable Nutsch (Büchner) filter and assess residues visually.
- Solution stability: Determined by storing the prepared solution for 2 hours at the chosen storage temperature (e.g., 60 °C, 30 °C or 25 °C), then mixing and filtering to assess precipitate formation or change in flow characteristics.
- Evaluation criteria:
- Visual assessment of filter residues (dried filter) to determine the application solubility limit (reported in g/L).
- Flow‑through time measured with a stopwatch; a sudden increase indicates exceeded solubility or unstable solution.
- Apparatus & reagents (examples specified):
- Wide‑mouthed Erlenmeyer flask (500 ml), thermostatic heating bath with magnetic stirrer, water bath for storage, heatable Nutsch filter (inner diameter ≈ 70 mm, capacity ≥ 200 ml), vacuum apparatus adjustable to 3–4 kPa (≈300–400 mm water), filter paper (70 mm ±2 mm), and analytical grade water (ISO 3696 grade 3).
- Reporting: Test report must include standard reference, dye identification, filter type/manufacturer, application solubility limit with dissolving temperature (g/L), solution stability (g/L) with dissolving/storage temperatures, flow‑through time (if used), observations and any deviations from the procedure.
Practical applications and users
- Quality control and R&D in textile dyeing to confirm suitable dye concentrations for application and to avoid precipitation during processing.
- Dye manufacturers to characterize commercial product behavior under typical processing temperatures.
- Independent textile test laboratories and certification bodies performing colour fastness and dye compatibility testing.
- Process engineers and formulators who must set safe working concentrations and storage conditions for water‑soluble dyes.
Related standards
Keywords: EN ISO 105‑Z07, ISO 105‑Z07:1995, water‑soluble dyes, application solubility, solution stability, textile dye testing, Nutsch filter, colour fastness tests.