Unit 3: Weaving simple structures
Introduction to Weaving notes · PTU syllabus (BSTD 102-20)
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Unit summary
This unit moves from planning to weaving: choice of reed, calculation of warp length and width, plain weave and its variations on two shafts, creative weft materials and colour-and-weave effects.
After this unit you can
- Choose a reed for a given yarn and fabric
- Calculate warp length, ends and width for a sample
- Weave basket, warp-rib and weft-rib variations
- Plan colour-and-weave effects and creative weft samples
PTU syllabus topics
- Usage of different reeds
- warp length and width calculation
- weaving plain weave and its variations (basket weave, rib weave) using 2 shafts
- creative weaving with non-conventional weft materials
- colour and weave effect samples
Plain weave
One over, one under
Firm, simple
Basket weave
Two or more threads together
Checked, softer
Warp rib
Groups of weft with single warp
Ribs across the width
Weft rib
Groups of warp with single weft
Ribs along the length
Topic 1
Reeds and reed numbers
The reed number is the count of dents per unit length (per inch or per 10 cm). The right reed spaces the warp so that fabric is neither crowded nor open.
| Reed | Yarn | Fabric |
|---|---|---|
| Coarse (8–12 dents per inch) | Thick wool, jute, rug yarn | Open, heavy, textured |
| Medium (12–24) | Cotton, silk, DK yarns | General-purpose cloth |
| Fine (30 and above) | Fine cotton and silk | Lightweight shirting and scarf fabric |
If two ends are drawn through each dent, ends per inch = dents per inch × 2.
Topic 2
Warp length, ends and width
Ends per inch (EPI)
Dents per inch × ends per dent
Total ends
EPI × width in inches (+ selvedge ends)
Warp length
Finished length + take-up and shrinkage allowance + loom waste
Yarn needed for warp
Total ends × warp length
Example
Sample scarf 8 inches wide, 12-dent reed, 2 ends per dent: EPI = 12 × 2 = 24; total ends = 24 × 8 = 192 (plus a few selvedge ends). For 60 inches of finished cloth with 10% allowance and 20 inches of waste: warp length = 60 + 6 + 20 = 86 inches. Warp yarn = 192 × 86 = 16,512 inches (about 460 metres).
Exam tip
Always calculate in the same units, include selvedge ends and add loom waste: a short warp is the commonest planning mistake.
Topic 3
Plain weave variations and creative weaving
Basket weave uses groups of ends and picks that move together; warp rib makes ridges across the width; weft rib makes ridges along the warp
| Variation | Construction | Look and use |
|---|---|---|
| Basket (hopsack) | Two or more ends and picks work as one | Loose, flat, absorbent; blankets, suiting |
| Warp rib | Plain weave with ends grouped; picks single | Fine cross ribs; poplin, cotton dresswear |
| Weft rib | Picks grouped, ends single | Heavy lengthwise ribs; ottoman, grosgrain |
Creative weaving uses non-conventional weft materials such as strips of cloth, rope, grass, paper yarn and wire. Thick wefts need coarse reeds and a loose beat; the warp is usually fine and strong so the weft shows. Colour-and-weave effects are patterns made by interplay of coloured warp and weft with a simple weave, for example hounds-tooth, pin-stripe and log-cabin patterns.
Alternating light and dark in both systems shows dots or checks; changing the order of colours changes the effect without changing the weave
Key terms
- Reed number
- Dents per unit length
- Selvedge
- Firm edge of a fabric
- Basket weave
- Groups of ends and picks weaving together
- Rib weave
- Ridged plain-weave variation
- Colour-and-weave
- Pattern from coloured yarns and a simple weave
- Waste
- Warp length left at the loom end
Quick revision
- EPI = dents per inch × ends per dent.
- Warp length = finished length + shrinkage + waste.
- Basket, warp rib and weft rib are plain-weave variations.
- Colour order creates check effects.
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.How is the reed number defined?
- Q2.Find the EPI for a 10-dent reed with 2 ends per dent.
- Q3.Name two variations of plain weave.
- Q4.What is a selvedge?
- Q5.Give two non-conventional weft materials.
- Q6.What is a colour-and-weave effect?
Long-answer questions
- Q1.Explain how to calculate warp length and total ends for a sample, with an example.
- Q2.Describe basket, warp-rib and weft-rib weaves with diagrams and uses.
- Q3.Explain colour-and-weave effects and creative weft weaving.
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