Overview
ISO 6836:1983 specifies a laboratory method to evaluate the activity of wetting products for mercerization (mercerizing agents) by measuring the shrinkage rate of cotton yarn hanks when exposed to caustic (sodium hydroxide) mercerizing baths. The standard is aimed at testing surface active agents used to improve penetration of mercerizing liquor into cellulose fibres, a key factor that controls effectiveness and processing time in mercerizing operations.
Key topics and requirements
- Scope: Method applies only to mercerizing/causticizing baths and wetting products used in those baths.
- Test principle: Immerse a prepared hank of smooth cotton with a fixed weight attached, then record longitudinal shrinkage at timed intervals; the speed and extent of shrinkage indicate wetting effectiveness.
- Sample preparation:
- Test hank: wind on a 1 m perimeter winder to obtain a hank mass of 1 ± 0.2 g, fold to approximately 24 cm.
- Conditioning: store hanks for at least 24 h at 20 ± 2 °C and 65% ± 2% RH before testing.
- Reagents and solution:
- Mercerizing liquor: sodium hydroxide solution prepared as described in the standard (example: dissolve 270 g NaOH in 1 litre water as given).
- Use analytical-grade reagents and distilled or equivalent water.
- Apparatus:
- Two accepted measuring setups: Hintzmann apparatus (millimetre scale and weight) or a servo apparatus (graduated disc with moving needle).
- Typical weights mentioned: a small weight 10 ± 0.1 g and a counterweight about 50 g (selection depends on yarn type and must be reported).
- Test procedure and data:
- Prepare solution immediately before testing (first solution used within 15 minutes).
- Measure shrinkage at 10 s intervals up to 90 s, and finally at 300 s (5 min); perform five series and use arithmetic means.
- Results expressed as rate of shrinkage (mm/time), percentage shrinkage, and time to reach 50% of total shrinkage (determined via plotting/logarithmic scale).
Applications and users
- Textile testing and quality control laboratories assessing mercerizing wetting agents.
- Chemical manufacturers of surfactants and mercerizing auxiliaries evaluating product performance.
- Textile mills optimizing mercerizing process parameters to reduce cycle time and improve fabric uniformity.
- Standards organizations and R&D groups comparing wetting efficiency across formulations or yarn batches.
Related standards
- ISO 607 (sample division for surface active agents and detergents) is referenced within ISO 6836:1983.
- Developed by ISO/TC 91 (Surface active agents).
Keywords: ISO 6836:1983, mercerizing agents, surface active agents, wetting products, shrinkage rate, cotton, mercerization testing, Hintzmann apparatus, servo apparatus, sodium hydroxide solution.
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