Silk Testing, Grading and Quality Control
Domain focus
Silk testing, grading and quality control tests how raw silk and cocoons are measured and classified. The exam covers denier, tenacity, elongation, cohesion, evenness, cleanness and neatness, and the logic of grade.
Core rules and concepts
- Testing requires representative sampling and standard conditioning because moisture changes mass and strength.
- Denier is the mass in grams of 9,000 m of yarn; a higher denier means a coarser yarn. Mulberry raw silk is usually a fine denier yarn.
- Tenacity measures strength per unit linear density, often in g/d; elongation measures stretch at break. Both indicate processing performance.
- Cohesion counts the strokes needed to break a filament bundle; evenness describes variation along the yarn.
- Cleanness refers to large defects such as slugs; neatness refers to smaller imperfections. Winding tests record breaks.
- Grading combines measured properties; a higher grade indicates more uniform, cleaner and stronger silk.
Worked example
A 450 m sample weighs 0.15 g. Denier = (mass in g ÷ length in m) × 9,000 = (0.15 ÷ 450) × 9,000 = 3.0. Reasoning: denier is a linear-density unit based on 9,000 m; the calculation converts the sample to that standard length. A result of 3.0 d is a medium-fine raw silk, not a strength value.
Traps that cost marks
Thinking higher denier is better; testing wet samples; using one cocoon as a lot sample; confusing cleanness with neatness; reporting tenacity in denier.