Textile Structure
how cloth is put together
Concept

Shrink-resist — where it appears

A treatment that stops wool felting by degrading or bridging its scales so the two friction coefficients converge. It is describable by one number — how far the gap is closed — and closing it completely stops the ratchet dead.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

What a shrink-resist treatment has to do. Net displacement per cycle of agitation as a treatment closes the gap between the two friction coefficients. The chemistry is sold as gluing the scales down; what it has to achieve is arithmetic — make the fibre slide equally well both ways and the ratchet has nothing to rectify.

Shrink-resist is one number

Machine-washable wool is sold as a coating that glues the scales down. What the treatment has to achieve is narrower and more exact — make the fibre slide equally well in both directions, and the ratchet has nothing left to rectify, whatever the friction happens to be.

finishing · Felting The ratchet a wool fibre is. A fibre with its scales, and the two strokes of one cycle of agitation. The push is the same in both directions; the distance is not, because the scales resist tip-first motion more than root-first. Every cycle therefore nets a displacement in one direction, and no amount of further agitation undoes it.

Why felting needs water

Wool felts in a wash and not in a drawer, and the usual explanation is that water lubricates the scales. It does the opposite of that. Water lowers one of wool's two friction coefficients and raises the other, so it widens the gap the ratchet rectifies — and what follows is a saturating function of the ratio, not of either coefficient.

finishing · Felting

Named alongside it

The objects these essays reach for when they reach for this one.

FeltingFrictionWoolAgitationDirectional frictionFibre migrationIrreversibilityMoistureRatchetSwelling

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