The fabric just removed from the machine is rough, unpleasant to the touch and is not suitable for sewing clothes and other textile products. To improve the consumer properties of the fabric, it is processed in several stages: remove impurities, bleach, dye, apply the drawing, impregnated with compounds that repel dirt and water. The technology for processing the web depends on the raw material from which the fabric was made, and on the purpose of the finished textile product. In the article you will find out what types of finishes are available, how various materials are processed, and what properties they acquire due to this. The finishing process improves the physical and decorative properties of materials.
Types of fabric finishes: general information
In the process of processing the fabric are 4 stages of finishing: preliminary, coloristic, final and special.
At the preliminary stage, the canvas is cleaned of impurities, softened, bleached, prepared for subsequent coloring, impart density or, conversely, porosity.
At the second stage, the fabric is dyed and a drawing is applied to it. Coloristic decoration is aimed at improving the decorative properties of the material.
At the final stage, the fabric is starched and smoothed to give it a presentation.
The purpose of the special finish is to give the canvas special properties: repellent water and dirt, antistatic, protection from moths and germs. In the process of special finishing, the decorative qualities of the material are also improved. Sustainable embossing is applied to the fabric, corrugated, give a metallic sheen.
Preliminary
Preliminary finishing is needed to prepare the canvas for painting and drawing. Types of fabric finishes depend on the raw material composition of the canvas and vary for cotton, linen, silk and wool.
To remove the ends of the fibers from the surface of the canvas and make it smooth, scorching is used. This type of fabric finishing is carried out on displaced machines. This treatment is used for cotton fabrics, linen, wool and silk.
The process of removing organic impurities and dressing from a fabric is called desizing. A dressing is an adhesive substance that is processed by warp threads to give them strength and smoothness. The canvas is soaked in baths with warm water for a period of 4 hours to a day, depending on the raw material composition and density of the material.
To give the canvas softness, boiling is used. Cotton and linen are boiled in alkaline solutions with the addition of surfactants at a temperature of 100-130 degrees Celsius in closed boilers for 1-6 hours. Silk is boiled at lower temperatures, on the order of 90-95 degrees Celsius, for 1-3 hours. For processing silk, a more gentle soap solution is used.
The natural color of the canvas is usually gray or taupe. To give it whiteness, bleaching is used. Silk fabrics are not bleached due to the fact that natural dyes are removed during the boiling process. A linen sheet needs to be bleached in 4 stages due to the high content of organic impurities in the fibers of the threads. The technology of this type of fabric finishing involves the use of chemical and optical brighteners.
Mercerization makes fabrics more durable and shiny. The cloth absorbs water better and stains, is less polluted and better washed. In the process of mercerization, the tissue is treated with sodium hydroxide solution for 30 seconds. This type of fabric finish is used for combed cotton fabrics.
For processing cloth fabrics use a roll. In the process of such processing, the wool fibers are interlinked by the scales completely or partially covering the weaving pattern. Many consumer properties of the canvas depend on the degree of tissue roll, which is weak, moderate and strong.
Thermal protective properties of the fabric depend on the presence of air voids in the material. Teasing gives the canvas porosity and softness. For such processing of fabrics, special napping machines equipped with a needle drum are used. The more times the web passes through the drum, the softer and warmer it will become.
Some pile fabrics additionally undergo the ratification process. Such processing allows you to arrange the pile in the form of a pattern or ornament.
For silk fabrics apply revitalization. This treatment gives the canvas a characteristic sheen and crunch. For revitalization, use weak solutions of organic acids, in which the canvas is placed for a short time.
Weighting helps to add extra density to silk. The canvas is treated with salts of heavy metals, as a result of which the tissue mass increases by 20%. “Weighted” silk is used for sewing curtains, suits, dresses.
Coloristic
In the process of color finishing, the fabrics are dyed and a pattern is applied to them. These types of decorative finishes are designed to give aesthetic qualities that affect the competitiveness of the final product.
Dyeing
Painting the canvas improves its consumer qualities. For painting the paintings using acid, direct, vat, sulfur, active and some other dyes. The type of dye depends on the raw material composition of the raw material. In the process of dyeing, the fabric goes through three stages. The first is the adsorption of dye molecules on the surface of the tissue. Further, in the process of diffusion, the dye penetrates into the fibers. In the third stage, the dye molecules are fixed on the inner surface of the fibers. The speed of the staining process and its resistance depend on the size of the dye molecules. Of no small importance is the temperature of the dyeing process. In the process of such finishing the canvas acquires a uniform color both on the surface and in thickness. This fabric is called plain dyed.
Print
The process of applying a picture to a canvas is called printing. Apply the drawing to the fabric both by machine and manually. Hand painting is used only for exclusive piece goods: scarves, scarves, tablecloths. The main types of finishing fabrics include printing: direct, etched and backup.
Direct printing is the process of applying a pattern to pre-bleached fabric. A variation of direct printing is the background, when the drawing is applied to a canvas painted in bright colors.
Etching print is used to obtain a white pattern on a dark background. In this case, a special bleaching composition is applied to the one-colored fabric. To obtain a color pattern, a persistent dye is added to the etching solution.
In the process of back-up printing, a special solution is applied to the fabric, which protects the fabric from dyeing. Further, the material is subjected to smooth dyeing. Processed spots remain white and form a pattern.
You can apply the picture to the canvas using various devices: stencil, spray, using a printer. The latter method is called direct digital printing. Spraying the fabric with fabric is called airbrushing. It is manual and machine. For the decor of T-shirts and overalls, thermal printing is often used. The prepared drawing is transferred from the substrate to the canvas with a hot press. Applying a patterned color to a wet canvas allows you to achieve the effect of a watercolor painting. This finish is called watercolor print.
Final
After sizing, boiling, bleaching and coloring, the material has a loose, wrinkled, warped appearance. To fix this and give the canvas a marketable appearance, a final finish is needed.
Sizing
In the sizing process, the fabric is treated with starch, salt, soap, oil, acids, cellulose solution, synthetic resins. Processing with starchy solutions gives the material smoothness, elasticity, rigidity. Glycerin and table salt make the fabric soft, hygroscopic, moist to the touch. Stearin soap and alizarin oil soften and give elasticity. Ultramarine makes bleached fabrics bright white. Salicylic and boric acid gives the tissue antiseptic properties. For resistance to abrasion, the fabric is impregnated with organic solutions based on silicon. Synthetic resins, such as latex, protect the fabric from shrinkage and increase its wear resistance.
Widening
To remove the warps of the canvas and give it a standard width, apply the expansion. Moistened fabric is fixed along the edge on the chain closures of the wide machine. The chains move and move away from each other, as a result of which the weft threads are straightened, and the warp threads bend. By changing the speed of one of the chains, you can fix the distortions of the fabric. In the process of such finishing the length of the canvas is slightly reduced.
Calendering
Calendering helps make the material nasty. The calender consists of a system of shafts sheathed with different materials and heated with steam. The shafts are metal smooth and engraved, upholstered in textile or paper. Calendering helps to add dullness, gloss, gloss, gloss to the canvas. The effect of the finish depends not only on the material of the shaft upholstery, but also on temperature and pressure.
Special
To give the fabric special properties help special types of fabric finishes. To make the material waterproof, synthetic resins, bitumen, and rubber are applied. Such processing is relevant for tents, overalls, tarpaulins. The water-repellent effect can be achieved by impregnating the fabric with stearin, wax, silicones. Dirt-repellent finish is applied to upholstery fabrics and workwear. For antistatic finishes, stearic acid derivatives are used. Metallization is used to increase the resistance of the material to high temperatures and improve electrical conductivity. To make the fabric refractory, use salts of silicic, boric and phosphoric acids. This finish is indispensable in the manufacture of workwear for firefighters. Woolen fabrics are treated with fluoride salt solutions to protect against moths. Antimicrobial treatment is used for tent fabrics, linoleum substrates, fishing nets. Treatment with salicylic acid, phenols and copper salts protects the tissue from decay.
In addition to special properties, in the process of special finishing they also improve the decorativeness of fabrics. They are corrugated, permanently embossed and varnished.
Finishing fabrics from various raw materials
Cotton fabrics are scorched, dressing is removed, and boiled to give it softness and hygroscopicity. Next, the fabric is bleached using chemical or optical compositions. Mercerization of the stretched fabric makes it softer and stronger, and free - allows you to create a corrugation effect. Teasing is used for the production of flannel fabrics. The painted and colored canvas is finished, smoothed and smoothed.
The pretreatment of linen is similar to cotton, but acid treatment is added. They help reduce the content of cellulose impurities and bleach the material. Flax bleaching takes place in 4 stages. After color finishing, the fabric is treated with sizing compositions, aligned and calendered.
Woolen fabrics are scorched, boiled, felted, teased. To create a textured drawing, ratification is used. Rarely bleach wool, as the strength of the fibers decreases. In the process of final processing, the wool is dried, leveled, pressed to increase density, cut the pile, steam treated to reduce shrinkage.
Silk fabrics singe, boil, revitalize to give crunch and shine, weight to increase density. The dyed silk is finished and leveled. To create a relief ornament, the canvas is treated with substances that enhance shrinkage.
In production, different types of fabric finishes are used. They are aimed at improving the physical and aesthetic properties of materials. Types of finishing fabrics are preliminary, coloristic, final and special. In the process of preliminary finishing, the canvas is singed, dressed, boiled, bleached, rolled, ratified, weighted. Pre-treatment improves the physical properties of the fabric and prepares it for dyeing. In the process of colorization, the canvas is painted and a drawing is applied to it. The final finish is aimed at giving the material a marketable appearance. The canvas is finished, leveled, calendered. A special finish gives the materials special properties: resistance to water, oils, fire, protects from insect pests, prevents the growth of bacteria and decay. Fabric finishing is aimed at improving the consumer properties of materials and appearance. Fabrics according to the method of finishing are singed, boiled, bleached, weighted, dyed, colored.