Wet Felting is a technique used to mesh wool fibres together using a soapy medium.
It’s precise history is unknown although it is thought to have originated pre-bronze age with a number of cultures have folklore about it’s beginnings mainly regarding a long journey and wool being packed into their sandals to cushion the feet, when they arrived the friction along with sweat.
Nomadic people created huge felt sheets by laying out fibres, wetting, rolling them up tightly and then dragging them behind horses or camels to get enough friction to full them. These sheets were then used to create yurts.
Wool is hair, and contains keratin, on the surface of each strand is a lot of scales, by overlapping these strands in different directions and adding soapy water and agitation the fibres full together creating felt, once felted the change is permanent and can’t be undone. Soap is added as a lubricant and because heat opens the scales, it is quicker to felt with hot water.