Felt has been known and used for centuries, gaining, as time went on, many new uses in widely separated fields.
Ten fundamental properties of this material account for its application for many dissimilar purposes throughout the wide range of manufacturing industries.
Knowledge of felt is combined with analysis of the motives determining its use in the process controls which shape the design of American Felts.
Certain materials are so readily obtained and so easily worked that everyone is more or less familiar with them. This is true of wool felt. It is also true of wood, brick, brass, glass, and a number of other materials. All of these can be worked by hand and therefore are closely associated with mechanics of everyday life. These common materials, besides being handy have many industrial applications for which they are classed as raw materials, even though they may be highly processed before they reach the manufacturing plant.
But the identity of the raw material often vanishes in the finished product. Hence felt, which had been commonly known and used for centuries, and is used today by nearly every manufacturing establishment, remains an inconspicuous but essential ingredient, whose functions are too often unrecognized in the Babel of the industries. Its astonishingly varied employment throughout the industrial world is due to the fact that the natural properties of felt, singly or in combination, fit it for many different uses, some quite simple; others complex. A section of the American Felt Company’s Trade Mark. The sandaled foot, symbolizes one such combination. The inner sole of the sandal, slipper or shoe separates the soft foot of the wearer from the harsh outer sole, affording protection by means of a resilient support.
Among the fundamental uses for felt, therefore, are separating, protecting, or surfacing, is also extended to include finishing or ornamentation. So here are five different uses which are basic to this material. Five other equally basic purposes which singly or in combination encourage the use of felt are sealing, wicking, filtering, friction and insulation. We may say, then, that there are at least ten fundamental properties which account for the widespread employment of felt. Can be so controlled during manufacture as to magnify one or more of the physical properties by whose terms the ten fundamental properties are measured.
By way of illustration, felt for polishing metallic mirrors such are used in fine instruments, is as soft and silky as a kitten’s ear, while the felt use by lapidaries in polishing gems must be harder and more coarse. Felt used to retain lubricant at a bearing and, at the same time, exclude grit, must be impermeable, but felt that is used to filter out bacteria clouds during the manufacture of flavoring syrups is required to have a very fine and uniform degree of porosity.
These varied characteristics are all derived through process control from a common source. They are based on the unique character of a single raw material which is sheep’s wool. Wool felt is one of the oldest materials produced from natural sources, and its oldest known uses were for bodily protection and comfort. Tents, coats, boots and blankets or many ancient European and Asiatic tribes were made of felt. Soldiers in olden times wore felt-lined helmets and carried felted shields. Caesar organized a light brigade whose equipment included felt breastplates as a protection against the weapons of the enemy. Many of these traditional uses continue and the production of felt for footwear and apparel form an important part of the American Felt Company’s annual business.
Felt in footwear fulfills one of the most intimate and personal uses imaginable, yet very few people have noticed how extensive that use is. Felt slippers, more comfortable than the proverbial old shoe, are a derivation from the ancient monk’s sandal, and history identifies his generation as of the Eleventh Century.
Felt boots are indispensible for arctic wear. Inner soles contribute to the comfort of men of the open spaces. Less familiar are the metatarsal pads and arch supports of felt which ease foot travel for many of the afflicted; artificial hands and feet are carved from a kind of felt that has the firmness of human muscle.
Even that very confidential pain-preventer, the corn plaster, is sheep’s wool. It is sterilized, medicated, faced with an adhesive, and it owes its principal virtue to the particular fact that sheep’s wool is resilient. One entire department in an American Felt Company mill is set apart for the production of surgical felts, which naturally require special materials and treatments and very exacting controls.
Then again, along about the time of the War between the States, ladies derived great personal comfort from petticoats made of felt. But today the uses of felt in feminine apparel are more ornamental, as well as conspicuous, thanks to special techniques in dyeing and the artistry of New York, Hollywood and Paris. Hats, handbags and accessories, in all their softness and contour, follow the fashions and colors of the style season. As in footwear, however, apparel felts have many uses of which the wearer may drape and substance to outer materials which otherwise would form a wrinkled and baggy garment. They provide the texture, like the felt backing for coat collars, these are hidden, structural parts of the clothing.
Mechanical felt parts used in machines or in mechanical processes, date back more than two hundred years, though today they form the major part of the production in America’s mills. Their origin, at least in organized mechanism, traces back to the invention of the pianoforte in 1709 and its improvement some thirty years later by the introduction of the felt-covered hammer, whence the development of the distinctive material known as hammer felt. Unlike the “new kind of cloth,” the legendary discovery of St. Feutre, here was a thick, hard, yet springlike substance, which resembled the whitewood of the Deacon’s One Hoss Shay in that it would “cut like cheese, but last like iron, for things like these.” Cut to fit the wooden hammer-head and glued in place, the felt would literally outlast several lifetimes. It would strike a tremendous blow, yet always, with the same impact produce the same kind of a tone from the resounding strings.
But felt in the piano does more than hammer the strings. It checks parasite vibrations between the pins and bridge, provides a damper to mute the singing wire after the note had been struck, supports, guides and cushions many parts of the action and so muffles the intricate system of parts that the piano is never thought of as a machine with a chattering voice of its own, but only as an instrument for the production of controlled sound.
Hammer felts were first made in this country about 1871.
Within a few years, American’s felts were being granted highest awards at world’s fairs in Vienna, Paris, Philadelphia and Chicago. A quarter of a century from its inception, the pioneer business in this line became a constituent in the American Felt Company, which today lists nearly fifty grades of piano and organ felts, including, in the old trade terminology, hammer, butt, backcheck, damper, muffler, action, pipe stop and swell.
Contrasting sharply with the uses of felts as intermediates in mechanisms of various kinds, is its functional employment in grinding and polishing.
Among the oddities here disclosed to the uninitiated is the fact that a scratch wheel, used in finishing plate glass, does not put scratches in, but takes them out. Furthermore, it does not grind or polish, in the sense of abrading the crests of superficial roughness, but actually softens and flows the surface until depressions, such as scratches and other flaws are filled and brought up to level by a flowing action peculiar to this one type of operation. Felt is used extensively in grinding and polishing lenses- including here, the use of fine abrasives, such as rouge—from eye-glasses all the way up to huge telescopes used in astronomical research. Felt wheels are also used in finishing tile, marble and granite, in surfacing pottery and buffing metal ware before and after painting. Felt scrapers and rollers are used in rolling mills for scrubbing sheets of copper, brass, zinc and stainless steel. Felt cut in discs, stacked on a mandrel to form long rolls, is used to remove excess loading from silk and in napping satins.
An entirely different type of use for felt is in bolstering or backing other materials. Its employment as padding in clothing had been noted. A somewhat different use of the same class is in backing the abrasive sheet in sanding machines, such as are used in woodworking, shoe manufacture and metal finishing. In embossing leather and various coated fabrics, felt is used as a backing for the working material. It serves as a blanket in a plate etching and stereotyping. In screen printing, the felt blanket serves as a cushion and also absorbs excess pigment, squeezed through the silk. A long line of felts is used by the laundering industry. Pressing bucks, for the clothing trades, must be yielding to prevent scorching the material around the buttons, buckles and heavy seams, yet firm enough to set the goods. All sorts of authentic gear finds need for felt in lining or fillers for protective cushioning purposes, or grips to afford a firm hand hold.
Many thousands of small articles of ornament and utility have felt bases to prevent them from chattering when moved about, prevent noise, avoid denting and scratching polished surfaces; electric fans, telephone instruments, radio sets, ink stands and ash receivers, clocks and statuettes are protected in this simple but efficient manner. The catalogs of American Felt Company felts include a great variety of qualities which have been tested and approved for these and other application from the standpoint of cost, as well as the desired physical properties. Probably the greatest penetration of mechanical felts is in sealing ball bearings to exclude abrasive and corrosive substances and prevent loss of lubricants through leakage. In many cases felt-protected bearings are sealed away for the life of the machine.
Automotive equipment, imposing the toughest test of durability, requires oil-sealing rings and washers for pinion bearings, crankshafts, water pumps, propeller shafts and universal joints, front wheel hubs, rear axle shafts and at many other points. The kindred use of felt in storing and distributing lubricants depends upon its capillarity, or wicking ability. Felt lamp wicks are extensively used in signal lamps for burning heavy oil in all weathers. Wick-fed bearings for electric fans and other light machinery run into the millions of applications. The sponge-like character of felt also adapts it for use as a reservoir for feeding ink in a wide variety of automatic printing equipment, such as cash registers, mail cancelling machines, automatic telegraph instruments, wall paper printing, numbering machines and stamp pads.
Filtration is another ancient use of felt. In fact, existing names for felt in all languages, except the Oriental, derive from the ancient Greek pilos, pilaitos, and carrying the meaning to “to filter.” Cellulous and pyroxylin solutions for photographic films, paints, plating solutions, syrups, latex, alcohol and oil are filtered through felt. Gas masks and industrial respirators are fitted with felt filters, among other applications in this field. Felt is also an excellent insulator. In one sense it is used as an insulator to prevent the transfer of heat, and in another to prevents the communication of vibration throughout the entire range of periodicity from shocks and infrequent pulsations up to the frequencies of sound. These uses account for a long list of applications- stores, airplane insulation, gaskets and pads in refrigerators and cold rooms, glass mounting for metal sash and weather-stripping are among them.
Mechanical equipment, ranging from delicate instruments to high-speed machine tools used in precision work, is often mounted on felt pads to protect it from external disturbances. In other instances, machines having a high shock or vibration factor may be insulated to prevent the transmission of vibration to their surroundings. The extensive use of felt in airplanes is designed to isolate vibrating parts in many instances, but the kapok-felt linings for airplane cabins serve the dual purpose of dampening resonance and preventing the escape of the heat in the frigid higher altitudes. The ever-widening horizon encompassing the field of felt implies many startling demand upon the sales engineer.
Without a reasonably sound analysis of the technical requirement, how else could you safely recommend:
- A substitute for the wings of Mother Hen, in an incubator?
- Or specify the felt accessories to be used in achieving Madame’s permanent wave?
- Or prescribed the palm to be worn by a steel worker when handling hot metal…on a thread moistener for the full-fashioned hosiery mill?
- Or a disc for a floor-polishing machine?
- Or a saddle-pad for one of those huge stainless steel milk trucks?
- Or determine the diameter of a little plug to be blown by a compressed air through copper tubing in cleaning down a food-processing plant?
- A treatment for felt to be used in modeling a magnificent tunnel for Junior’s toy railroad?
- An impregnating compound to prevent the tarnishing of felt-wrapped silverware?
- Color selections for altar cloths and drapes to suit the calendar of the Church, and meet with ecclesiastical approval?
It is not only the know-how, but the know-why that modulates the design of American felts...