Fullers means in the bible: They were responsible for washing and whitening garments. They used soap made from salts and oil. It was either with carbonate or borax. Also see Jer. 2:22; Mal. 2:22; Mal. The Fuller’s Field 2 Kgs. 18:17; Isa. 7:3 was very close to Jerusalem’s walls, perhaps on the east.
(in Bible Dictionary)