Wool is a natural product with many fantastic properties: it is breathable, keeps the wearer nice and warm as well as being gentle on the skin. As far as looking after wool is concerned, the fibres are nevertheless delicate. If not washed correctly, you might as well throw the woollen jumper away.
But what causes a soft and cosy woollen jumper to become hard and lose its shape after washing? Each fibre is enclosed within a fine cuticle layer in a similar way to human hair. This protective layer can be roughened by moisture, overly high temperatures and friction during the wash cycle. Consequently, fibres become entangled and matted.
It makes no difference whether the jumper has been knitted with Merino, mohair or even alpaca wool. The basic properties are the same even though the fibres come from different animals.