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Fabric Design · Lecture 01
Introduction to Weaving and Fabric Construction
The three motions of a loom, the common weaving defects, and how a fabric construction is written and read.
SheddingPickingBeating-upConstruction notation
What a loom does, three times a pick
1 · Shedding
The warp ends are divided into two sheets — some raised, some lowered — to open a shed. Which ends rise on which pick is the design, and that is what this course is about.
2 · Picking
The weft is carried through the shed: by shuttle, projectile, rapier, or a jet of air or water.
3 · Beating-up
The reed pushes the new pick against the fell of the cloth, fixing the picks per inch.
Let-off (feeding warp from the beam) and take-up (winding the cloth) keep the process continuous.
Common defects and what they tell you
| Defect | What you see | Usual cause |
|---|---|---|
| Missing pick / missing end | A thin line across (pick) or along (end) the fabric | Weft break not detected; warp break with stop motion failing |
| Double pick / half pick | A thick weft bar, or a pick that stops part-way across | Two picks in one shed; pick breaking during insertion |
| Floats | Threads skipping over several others | Ends stuck together or a late shed |
| Crack (starting mark) | A band of lower pick density | Loom stopped and restarted without correcting the fell |
| Reed marks | Warp-way streaks | Too many ends per dent for the yarn |
Reading a construction
Yarn count in the English system is hanks (leas of 840 yd) per pound. A construction such as 20 × 16 / 128 × 60, 63", 3/1 gives warp count × weft count, ends × picks per inch, width and weave.
| A | B | |
|---|---|---|
| 1 | Warp count Ne | |
| 2 | Weft count Ne | |
| 3 | Ends per inch | |
| 4 | Picks per inch (finished) | |
| 5 | Width (in) | |
| 6 | Length contraction after the loom | |
| 7 | Total ends in the warp | 8,064 |
| 8 | Picks per inch to set on the loom | 55.2 |
| 9 | Yards of warp yarn per yard of fabric | 8,870 |
| 10 | Rough weight, GSM ≈ (EPI/Ne + PPI/Ne) × 25 | 254 |
blue = input (edit me)grey = formula (click to see it)
Because the fabric contracts in length when it leaves the loom, fewer picks are inserted per inch on the loom than are counted in the finished cloth — the lecture sets 55 picks on the loom for a 60-pick fabric.
Original lecture material
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