According to Wikipedia, Fulling, also known as tucking or waulking, is a step in woollen clothmaking which involves the cleansing of cloth (particularly wool) to eliminate oils, dirt, and other impurities, and making it thicker. In days gone by, the fullers were often slaves. In Roman times, fulling was conducted by slaves standing ankle deep in tubs of human urine and cloth. Urine was so important to the fulling business that urine was taxed. Urine, known as ‘wash’, was a source of ammonium salts and assisted in cleansing and whitening the cloth. By the medieval period, fuller’s earth, a clay material that has the capability to decolorize oil or other liquids without chemical treatment, had been introduced, pretty much eliminating the need for urine in the process.
Man after reading about Fulling, I am so glad I only have to clean the bathrooms!