water-repellent felt

Felt, made out of wool from sheeps are naturally water-repellent because of the lanolin (wool wax or grease). 

To become very clean wool , the shoren wool comes into a carbonizing proces.

This chemical and heating process will remove all virgin matter (and the lanolin) from the wool.

The wool is clean, but it will absorb now the water much faster.

To become water repellent again the felt has to go into a impregnation bath.