Fabric Contraction & Loom-state Shrinkage Tool

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. Three widths are compared: the reed the loom was set to, the greige fabric off the loom, and the finished fabric after the stenter.
2. The loom stage is calculated first because it happens first and because the reed width is a setting, not a measurement.
3. The finishing stage is calculated on the greige base, so a mill can compare it against the finishing route it used regardless of how the loom behaved.
4. Total contraction is taken end to end rather than by adding the stages, which would overstate the loss.
5. The required reed width reverses both stages at the same rates, so a target finished width can be turned into a loom setting directly.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

Substituting

The required reed width returns 72 inch, which is the check: feed the same two rates back and the calculation lands on the reed the fabric actually came from.

How to use it

1. Work through the input groups in order — Widths. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Total Width Contraction in the dark results panel — that is the headline figure, expressed in %.
4. Check the supporting rows underneath (Reed to Loom-state, Loom-state to Finished, Total Width Lost and Reed Width for This Finished Width) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Reed planning — choosing the reed width and reed count that will land on the contracted finished width after both stages.
• Width complaint diagnosis — splitting a narrow delivery between the weaving room and the finishing route instead of arguing about it.
• Costing — a fabric that finishes 2 inch narrow costs the buyer more per garment, because consumption is driven by usable width.
• Finishing route selection — comparing what a compactor, a stenter over-feed or a mercerising range does to width on the same greige.

Reading the result

Typical bands and what each one is telling you.

Assumptions and limits

• Reed-to-greige contraction is weft crimp and is set by the construction. Greige-to-finished depends on the process route and must be measured on your own range.
• Every input is bounded to the range normal practice occupies (Reed Width 1 to 250 inch, Loom-state (Greige) Width 1 to 250 inch and Finished Width 1 to 250 inch, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Standards and further reading

• ISO 22198 / ASTM D3774 — determination of fabric width, including where on the roll to measure.
• ISO 7211-3 — yarn crimp in fabric, which is the physical cause of the loom-stage contraction.

Questions people ask