Next comes "Wool Dyeing" or "Fatliquoring." This takes anywhere from 3-4 hours to complete. ugg boots After the skin is tanned, the wool may be dyed any of a variety of colors. Wool dyeing needs to be done at about pH 4.5-6 and at 60-65 degrees Celsius. Special "pelt reserve agents" must be added to keep the wool dye from staining the pelt. Once the dye is stable, the pH is lowered to about 4.0 to fix the dyes to the wool, and fatliquor (emulsified oil) is added to the solution. Fatliquors are part of leather manufacturing that help to lubricate the collagen fiber and allow them to move flexibly and freely once the skin is dried. This is what makes the leather feel soft.
