Hastings' Dictionary of the Bible (1898)
FUL'LER. The Hebrew word comes from the verb "to tread," because originally the clothing was trodden upon in tubs of water until the soap which had been dissolved had cleansed it. The fuller did not simply full new cloth, but washed clothing that had been worn. Among the primitive Hebrews washing was done at home by the women. Ex 19:10; Num 19:7. It was obligatory in the case of the leper's clothing. Lev 13:54. But in later times among the Hebrews, as among the Egyptians, as the monuments testify, washing was an especial and important business of the men.
2 Kgs 18:17; Isa 7:3; Isa 36:2; Mark 9:3. Mention is made in the Bible of the various substances used in this business, such as nitre, Prov 26:20; Jer 2:22; soap, probably the juice of some saponaceous plant, Mal 3:2. Chalk was rubbed into clothes for the same purpose. Since the fullers occasioned offensive smells, they carried on their work outside the cities. West of Jerusalem was their field; its removed position and the supply of water from the upper Pool of Gihon rendered the place very fit. See Fullers' Field. En-rogel was the fullers' fountain.