Felt, a fabric formed without weaving, by taking advantage of the natural tendency of the fibres of wool and certain kinds of hair to interlace with and cling to each other.
The property of felting or matting which the fibres of wool and hair of various animals have arises from their structure. When one of these fibres is examined by the microscope, it is found to be minutely notched or jagged, the barbs pointing to the tip of the hair. This serrated edge, and also a tendency to curl, cause these animal fibres to interlock, and so felt or mat when they are intimately mixed and rubbed in a moist state upon each other. Some fibres of this kind, however, such as human hair and horse-hair, are too nearly smooth or too rigid for felting purposes. Among the materials most suitable for felting are the wool, fur, and hair of such animals as the sheep, goat, ox, hare, rabbit, musquash, and beaver. Some of these are used chiefly for felt hats (see HAT). Felted cloth is made principally from wool, but less valuable substances are mixed with it.
The making of felted fabrics is a very ancient art in some parts of Asia, and to this day the thick nümds or nammads of Persia and Turkestan are remarkable not only for their durability, but for their beautiful ornamentation, produced by a felted inlay of coloured wools. It is said that thick felts made up into boots and gaiters form the only foot-covering capable of resisting the cold of a Siberian winter.
The first successful mechanical process for the manufacture of felt was invented by Mr J. R. Williams, an American, in the decade 1820-30, Mr Wells, also an American, being associated with him. Williams took out a patent for the process, or for a modification of it, in England in 1840, and about this time a large factory was erected by some capitalists at Leeds to manufacture felt cloth under the patent. The company speedily attained great prosperity, but in the full tide of its success the mill was destroyed by fire. Williams, whose whole property was in the concern, which was not insured, soon afterwards died of grief.
By the above process, not materially modified, felt cloth is still made. The wool is first formed into a thin lap or sheet on a carding-engine (see WOOLLEN MANUFACTURE). A number of these laps are piled upon each other till a sufficient thickness is obtained. At this stage the future piece of felt cloth is in a loose, open condition, sometimes called a fleece. It is then submitted to pressure in a machine with an upper and a lower series of rollers, between which it passes. Some of these are solid, and some are hollow and contain steam. It is by the rubbing action of these rollers, the upper series of which oscillate, that the fleece, under the influence of steam and moisture, becomes converted into a compact cloth. Fabrics so made are entirely held together by the interlocking of the fibres of wool.
There are other kinds of machines for making felted cloth. In one of these a heavy oscillating table is employed instead of rollers, by which several fleeces are felted at one time. Another, designed by a German engineer, is so constructed that the preparatory operations of opening and carding the wool, as well as the damping, pressing, and rubbing of the lap or fleece, are made continuous—i.e. all are done on one machine. In this case, rollers arranged in a vertical frame are used for consolidating the fleece into felt.
Such felt goods as druggets, carpets, and table-covers are usually printed with patterns in colours. The manufacture of felt for various purposes is extensively carried on in England, on the continent of Europe, and in the United States. Among the kinds made, besides those for furniture and dress purposes, are felts for polishing glass and marble, for saddle-cloths, for lining india-rubber fabrics, for parts of shoes, gun-wads, and hammers for piano-keys. Mixed or coated with asphalt, pitch, or tar, a coarse felt is used for covering roofs, vessels, and iron buildings. For these same purposes it is also combined with Asbestos (q.v.), this mixed kind of felt being likewise used for covering steam-boilers and pipes. The 'blankets' used on paper-making machines, though not strictly felts, are woven fabrics highly felted.