Washing in hot water that is carried on the woolen fabrics to cause itching and altering appearance, body and toughness, making them thicker, more compact and more resistant. The phenomenon is due to the exclusive "wandering" power of wool fibres. The final appearance of the fabric is different depending on the length of the process: it is transformed from a surface treatment that makes a fabric more compact and soft to an energetic treatment where the fibres thicken and interwoven to completely conceal the weave Eg military cloth).