What is Felting wool ? | Shrinkage of Wool | Relaxation

What is Felting wool ? | Shrinkage of Wool | Relaxation

Shrinkage of Wool

Shrinkage of wool occurs mainly due to scaly surface of wool and the elasticity of the wool fabrics and garments. It can take place in two ways, by relaxation or by felting wool.

Relaxation Shrinkage

RELAXATION SHRINKAGE is cause due to tension induced during the processing i.e. spinning, weaving and finishing. Wool is an elastic fibre, and will stretch when pulled during the fibre spinning into yarns, yarns knitted or woven into fabrics and during finishing of fabrics.

In the finished garment, the fibres sometimes retain some of this stretch; they have a property to try and return to their original unstretched state.

So long as the garment is keep dry, the fibres will be unable to recover their normal or default shapes & size. Wet fibres are soften and lubricate and are able to relax into more natural positions .

A garment made up from wool in this sort of 'touchy' condition will therefore shrink when it get wash. A shower of water will cause the relaxation shrinkage.


FELTING is unique to wool and other animal fibres. When a wool fabric is subject to mechanical action during wet felting of wool takes place. The fabric shrinks, but it also undergoes characteristic changes in its structure.

The fabric thickness increases and the fibres are matt into closely-packed masses. The outline and character of the yarn pattern in the fibre becomes thick. Hence, the fibre loses much of its elasticity. The appearance is altered and the surface get cover by fibres.

Pointing in one direction along the fibre, the scales on a wool fibre are arrange with their edges. This means that fiber is rougher in the tip to root direction, than in the root to tip direction.

A single fibre would therefore be able to move more readily through a mass of fibres in a root first direction then than in tip-first direction.

The continous compression and relaxation of wool fabric during any treatment tends to bend the fibres into loop inside the fabric and felting appears to take place most readily.

When ‘travelling fibres’ penetrate these loops to form knots and entanglement, felting wool yarn occurs

It has been shown that wool fibres will felt more readily when the tips of the fibres are softened or the roots hardened. If the tips are softened, the fibres are able to form loop more easily and if the roots are hardened the traveling fibres can penetrate more readily into the loops.

The tumbling or stirring actions of washing machines the prolonged use of the ‘posser’ (familiar in the north of England) and particularly any form of rubbing will all cause felting in wool.


What is Felting wool ? | Shrinkage of Wool | Relaxation What is Felting wool ? | Shrinkage of Wool | Relaxation Reviewed by Suraj Gupta on July 04, 2020 Rating: 5

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