Fulling or tucking or walking ("waulking" in Scotland) is a step in woolen clothmaking which involves the cleansing of cloth (particularly wool) to eliminate oils, dirt, and other impurities, and making it thicker. The worker who does the job is a fuller, tucker, or walker. The Welsh word for a fulling mill is pandy, which appears in many place-names.
Fulling involves two processes, scouring and milling (thickening). Originally, fulling was carried out by pounding the woolen cloth with the fuller's feet, or hands, or a club. In Scottish Gaelic tradition, this process was accompanied by waulking songs, which women sang to set the pace. From the medieval period, however, fulling often was carried out in a water mill.
These processes are followed by stretching the cloth on great frames known as tenters, to which it is attached by tenterhooks. It is from this process that the phrase being on tenterhooks is derived, as meaning to be held in suspense. The area where the tenters were erected was known as a tenterground.
In Roman times, fulling was conducted by slaves working the cloth while ankle deep in tubs of human urine. Urine was so important to the fulling business that it was taxed. Stale 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 had been introduced for use in the process. This is a soft clay-like material occurring naturally as an impure hydrous aluminium silicate. It was used in conjunction with wash. More recently, soap has been used.
The second function of fulling was to thicken cloth by matting the fibers together to give it strength and increase waterproofing (felting). This was vital in the case of woollens, made from carding wool, but not for worsted materials made from combing wool. After this stage, water was used to rinse out the foul-smelling liquor used during cleansing.
Felting of wool occurs upon hammering or other mechanical agitation because the microscopic barbs on the surface of wool fibers hook together, somewhat like Velcro.
Fulling mills 
From the medieval period, the fulling of cloth often was undertaken in a water mill, known as a fulling mill, a walk mill, or a tuck mill. In Wales, a fulling mill is called a pandy, and in Scotland, a waulk mill. In these, the cloth was beaten with wooden hammers, known as fulling stocks or fulling hammers. Fulling stocks were of two kinds, falling stocks (operating vertically) that were used only for scouring, and driving or hanging stocks. In both cases the machinery was operated by cams on the shaft of a waterwheel or on a tappet wheel, which lifted the hammer.
Driving stocks were pivotted so that the foot (the head of the hammer) struck the cloth almost horizontally. The stock had a tub holding the liquor and cloth. This was somewhat rounded on the side away from the hammer, so that the cloth gradually turned, ensuring that all parts of it were milled evenly. However, the cloth was taken out about every two hours to undo plaits and wrinkles. The 'foot' was approximately triangular in shape, with notches to assist the turning of the cloth.
There are several Biblical references to fulling (2 Kings 18:17; Isiash 7:3 and 36:2; Malachi 3:2; Mark 9:3). The first references to fulling mills are reported in Persia from the 10th century. By the time of the Crusades in the late eleventh century, fulling mills were active throughout the medieval Islamic world, from Islamic Spain and North Africa in the west to Central Asia in the east. They appear to have originated in 9th or 10th century in the Islamic world, either in the Middle East or North Africa. Mechanical fulling was subsequently disseminated into Western Europe through Islamic Spain and Italy in the 11th and 12th centuries.
The earliest known reference to a fulling mill in France, which dates from about 1086, was discovered in Normandy. The earliest reference in England occurs in the Winton Domesday of 1117–19. Other early references belonged to the Knights Templar by 1185.
See also 
|Look up fulling or tenter in Wiktionary, the free dictionary.|
- Jones, Gareth Daniel Rhydderch of Aberloch, reproduced from The Western Mail July 17, 1933 accessed at  June 19, 2006
- Adam Robert Lucas (2005), "Industrial Milling in the Ancient and Medieval Worlds: A Survey of the Evidence for an Industrial Revolution in Medieval Europe", Technology and Culture 46 (1): 1–30 [10–1 & 27]
- Lucas, Adam (2006), Wind, Water, Work: Ancient and Medieval Milling Technology, Brill Publishers, p. 278, ISBN 90-04-14649-0
- J. Gimpel, The Medieval Machine (2nd edn, Pimlico, London 1992 repr.), 14.
- Online Etymology Dictionary. Retrieved June 30, 2005.
- E. K. Scott, 'Early Cloth Fulling and its Machinery' Trans. Newcomen Soc. 12 (1931), 30–52.
- E. M. Carus-Wilson, 'An Industrial Revolution of the Thirteenth Century' Economic History Review, Old Series, 11(1) (1941), 39–60.
- Reginald Lennard, 'Early English Fulling Mills: additional examples' Economic History Review, New Series, 3(3) (1951), 342–343.
- R. A. Pelham, Fulling Mills (Society for the Protection of Ancient Buildings, (mills booklet 5), c.1958)
- A. J. Parkinson, 'Fulling mills in Merioneth' J. Merioneth Hist. & Rec. Soc. 9(4) (1984), 420–456.
- D. Druchunas 'Felting, Vogue Knitting, The Basics', Sixth & Spring Books, NY. (2005); p. 10.