Overview
ISO 105‑Z06:1998 - Textiles - Tests for colour fastness - Part Z06: Evaluation of dye and pigment migration - specifies a laboratory method to assess the propensity of dyes and pigments to migrate in a pad liquor system. The standard evaluates migration by differential drying of a padded fabric (partly covered by a watch glass) and quantifies migration either visually (grey scale) or instrumentally (reflectance/K‑S calculations). It is used to compare dyes, thickeners, electrolytes and migration inhibitors and to pre‑screen pad liquor formulations before scale‑up.
Key topics and technical requirements
- Scope and purpose: Measures dye/pigment movement between fibres, within a substrate or between substrates caused by capillary forces.
- Definitions: Clear definitions for dye, pigment, migration and pad are provided to ensure consistent interpretation.
- Sample preparation
- Recommended fabrics: 65:35 polyester:cotton blend for disperse/vat/pigments; 100% cotton for reactive dyes (other fabrics may be used to match production ranges).
- Typical specimen sizes: e.g. 150 × 300 mm for Procedure A; ~110 × 220 mm for Procedure B.
- Wet pickup: typically ~60% by mass (adjustable to simulate production).
- Two procedures
- Procedure A (room drying): Fabric padded, placed on a glass plate and partially covered with a watch glass; dried at room temperature (overnight).
- Procedure B (oven drying): Fabric mounted between watch glasses on a pin frame and dried horizontally in an oven at (100 ± 2) °C for about 7 minutes.
- Evaluation methods
- Visual: Compare covered vs uncovered areas using ISO 105‑A02 grey scale (grades 5 to 1).
- Reflectance: Measure reflectance at λmax, convert to K/S (Kubelka‑Munk), and calculate percent migration: M = 100[1 − (K/S)a/(K/S)b].
- Reporting: Test report must cite ISO 105‑Z06:1998, pad liquor composition (colorant, inhibitor, thickener, electrolyte), substrate and wet pickup, drying conditions, evaluation method and any deviations. Precision has not been established.
Applications and users
- Quality control and R&D in textile dyehouses and mills for:
- Comparing migration behaviour of dyes and pigments.
- Evaluating the effect of migration inhibitors, thickeners and electrolytes.
- Pre‑screening pad liquor formulations before continuous dye range trials.
- Typical users: textile technologists, colorists, laboratory technicians, chemical suppliers, and instrument manufacturers (spectrophotometers).
Related standards
- ISO 105‑A02:1993 - Grey scale for assessing change in colour (normative reference for visual evaluation).
- Other parts of the ISO 105 series cover complementary colour‑fastness tests and assessment methods.
Keywords: ISO 105‑Z06, dye migration test, pigments, textiles, colour fastness, pad liquor, migration inhibitors, grey scale, K/S, spectrophotometer.