There are two main types of ingredient that may result in the deterioration of a Lambswool cardigan or wool sweater washed under incorrect conditions:
Sorry, but it gets a little technical from here on.
In addition to the normal surfactants, emulsifiers, perfumes etc contained in ordinary detergents, the so-called ‘bio’ detergents also include a small quantity of enzymes. These are protein digesting biological catalysts, and are effective at decomposing stains or soiling in which protinaceous material is the main constituent. Egg, blood, and most other food stains etc are all protein based and will be effectively removed by enzyme-containing detergents.
The problem is that like fur and hair, the histological structure of the fibre in Lambswool cardigans and sweaters is based on the polypeptide and disulphide linked protein Keratin. This can itself be affected by the biological components in some of these detergents. It is possible that enzymes may attack the cell membrane complex of the wool fibres, and lead to disintegration of the structure into its component cortical cells, this leads to a hole filled Lambswool garment.
In order to increase their apparent cleansing efficiency, some washing powders include bleaches or ‘bleach activators’. These are usually of an oxidative nature, though can also be reductive. Again, because of Lambswool and wool’s inherently natural characteristics, the fibre can be damaged by strong solutions in these bleach-containing powders.
More often than not, these types of washing powders will cause fading of colour to Lambswool cardigans and sweaters, even erosion of the fibre cuticle and a corresponding deterioration in resilience and strength.