Nevertheless, despite these benefits of wool, fact remains that people across the globe have felt frustrated by one specific aspect of their natural wool sweaters -- they permanently shrink when washed in warm water. The explanation for this phenomenon lays in the very structure of the wool. The material is as such formed from keratin protein, which is covered in microscopic scales. This structure allows for the wool to be flexible and worked with and the microscopic scales allow the textile to capture and retain heat. Still, when washed in warm water, and especially in washing machines during long programs that also include high levels of agitation, the wool sweaters shrink; and when this happens, the process is permanent; on the market, there are some product which claim to reverse the product, but such a process is irreversible.

In essence, when the wool sweaters are subjected to washing in warm water, the...

This causes the wool sweaters to shrink and also damages the quality of the fabric, which is no longer able to retain heat.
"According to Woolcrafting.com, a wool-crafting hobby site, wool is known to shrink during washing. This happens more often with heavy or hot loads, and wash cycles with a lot of agitation. This shrinkage is caused when the miniature scales tighten and cling to themselves and the keratin in wool. This also makes your wool sweater less effective against cold" (Koble, 2010).