Shearing: It is a mechanical finishing process to even or trim the nap or the pile on the fabric surface. Generally shearing is applicable to nap and pile fabrics in order to remove the irregularities in pulled yarn ends, knots and other surface flaws and to lay the nap or pile evenly on the surface of the fabrics. Shearing is carried out with the help of wide spiral cylinder that contains cutting blades diagonally. The working principle in shearing is just like a lawn mower. Before shearing, the fabric is passed over brushes that raise the fibre ends/yarn ends. Then it will be passed under the cutting blades which shear the pile/nap. Adjustments can be made to cut the pile as per the desired depth.
Brushing: Short loose fibres on the surface of the fabric can effectively be removed by brushing the surface of the fabrics. In case of nap and pile fabrics, brushing is carried out before shearing to help in laying the nap/pile at desired depth. Brushing is carried out by cylinders covered with bristles that raise the fibre/yarn ends and remove the loose fibre. Light brushing is done to spun yarn fabrics before singeing, so that the fabric will be smooth for further processing.
Creping: Interesting texture effects are produced on fabrics such as crepe effects. Different methods of producing crepe are in vogue in textile industry. Based on the method and the fabric, the durability of this finish varies. Plisse effects are produced on cotton fabrics by impressing sodium hydroxide in the form of strips or designs. Caustic soda makes the cotton cloth (like lawn) to shrink and the rest of the cloth puckers.
Seersucker effects are produced when printed patterns are in the form of stripes. Wax can also be used for obtaining temporary effects. In another method, engraved rollers with crepe pattern are impressed on resin finished cottons or thermoplastic fabrics to get the crepe effect. This effect produced is durable on cottons and permanent on thermoplastics. Crepe effects on silk are produced by chemical method of printing the fabric with a paste containing concentrated sulphuric acid and retained for few minutes. Later it is washed and neutralized with a weak alkali. Silk may become dull and slightly loose strength.
Napping: Napping produces soft fabrics with fuzzy surface. Wool fabrics are given fine nap finish using vegetable burrs called teasels. The fine thorns present on the surface of these burs pull the surface fibres when rubbed against the surface.
To resemble wool flannel, cotton, rayon and other spun yarn fabrics are often napped. Cotton after napping is termed as flannelette which not only resembles wool flannel but also produces warmth due to increased air cells.
Napping is carried out by utilizing the cylinders with fine metal wires and small hooks. Around 24 to 30 raising rollers of such type revolve around a large cylinder. Each raising roll is covered with 1/2" long wires placed at an interval of 1 1/16th inch and set at 450 angle to the surface to be raised. The wires on each roll are set at opposite angles to the rolls on either side which are called pile and counterpile rolls. The wires make the pile by pulling the fibre ends onto the surface. The pile rolls produce long pile while the counterpile rolls produce short pile on a relatively tensioned fabric. Later the pile is made even by shearing machines.
Napping can be done one side of the fabrics. Ex: for making sweat shirts, cotton fabrics are napped on the wrong side to provide warmth.
Napping is often carried out on both the sides of the fabric. Napped fabrics defer due to setting of the fuzzy surface. Single napping signifies that both the sides of the fabric have been napped in one direction. If the direction of the nap on either side is different, the fabrics are called as double napped fabrics.
The advantages of napping are:
Fabrics become soft after napping
Provides warmth which depends on the thickness of napping on fabrics.
It can act as a protection against objectionable luster.
Stains can easily be removed on napped fabrics as the stain is present only on the pile surface.
Disadvantages to the consumer:
It can camouflage sleazy construction
It can hide defective parts of a fabric such as holes, uneven construction etc.
Fulling: It is generally done to wool fabric to give compactness as the wool fabric after weaving appears loose and hard in texture. With this finish it is possible to make the fabric compact and softer to touch and impart warmthness as well. Only moisture, heat, friction and pressure are employed. Both woven and knitted wool fabrics can be fulled, either lightly or heavily. Boiled wool is an example of heavily fulled jersey.
Heat setting: The resin coated fabric mounted on a tenter frame is passed through an oven for a particular time and temperature, which is dependent on the fibre content. Heat is employed to stabilized yarns or fabrics made of heat sensitive fibres. Later the fabric is cooled to lock the shape. This fabric will be stable to any heat lower than the one it was set.
