Unit 1: Grey fabric inspection
Introduction to Chemical Processing notes · PTU syllabus (BSTD 201-20)
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Unit summary
Fabric straight from the loom is called grey (greige) fabric — it carries faults and impurities that must be found before processing. This unit covers grey fabric inspection and the characteristics and classification of impurities.
After this unit you can
- Inspect grey fabric and grade defects
- Classify natural and added impurities
- Explain why impurities must be removed
- Relate impurities to later processing problems
PTU syllabus topics
Grey fabric inspection, characteristics and classification of impurities
Natural
Wax, pectins, seed husks, colour
Added
Size (starch), spinning oils
Accidental
Dirt, stains, rust
Topic 1
Grey fabric inspection
- Fabric is passed over an inspection table or machine with back lighting; faults are marked, recorded and graded before it is accepted for processing.
- Up to 3 inches
- 1 point
- Over 3 up to 6 inches
- 2 points
- Over 6 up to 9 inches
- 3 points
- Over 9 inches or any hole
- 4 points
Points per 100 square yards
Total points × 3,600 ÷ (yards inspected × fabric width in inches)
Acceptance
Commonly 40 points per 100 square yards or less = first quality
- Common grey defects: broken ends and picks, floats, slubs, thick and thin places, oil stains, holes, reed marks, starting marks, wrong draft.
Topic 2
Impurities in grey fabric
Source
Present in the fibre itself
Added during spinning and weaving
Cotton
Waxes, pectins, proteins, natural colouring matter, mineral matter, seed and leaf particles
Size (starch, PVA), lubricants, oils, tints
Wool
Wool grease (lanolin), suint (sweat salts), dirt, vegetable matter
Spinning oils
Silk
Sericin (silk gum) 20–30%
Weaving oils, size
Synthetics
Few natural impurities
Spin finishes, oils, size
- Why remove impurities: they make fabric hydrophobic, prevent even absorption of dyes and chemicals, cause uneven shades, stains and harsh handle.
Key terms
- Grey (greige) fabric
- Unfinished fabric straight from the loom
- Four-point system
- Method grading fabric defects by length
- Natural impurity
- Impurity inherent in the fibre
- Added impurity
- Substance added during manufacturing, such as size
- Sericin
- Gum coating silk filaments
Quick revision
- Inspection method; four-point system; points per 100 square yards.
- Common weaving defects.
- Natural vs added impurities in cotton, wool, silk, synthetics.
- Effects of impurities on processing.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.What is grey fabric?
- Q2.How many points does a 7-inch defect get?
- Q3.Name two natural impurities of cotton.
- Q4.What is suint?
- Q5.Why must size be removed?
- Q6.What is sericin?
Long-answer questions
- Q1.Describe grey fabric inspection with the four-point system.
- Q2.Classify the impurities in textile fibres and explain why they must be removed.
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