Printing can be divided into direct printing, discharge printing and resist printing according to printing equipment.
1. Direct printing Direct printing is a direct printing on white fabric or on pre-dyed fabric. The latter is called overprinting. Of course, the color of the printed pattern is much darker than the dyed base color. A large number of common printing methods are direct printing. If the background color of the fabric is white or mostly white, and the printed pattern looks lighter from the back than the front, then we can judge that this is a direct printed fabric (Note: Because the printing paste has strong penetration, it is not suitable for light and thin fabrics. fabrics cannot be judged by this method). If the fabric base color is the same shade on both sides (due to piece dyeing) and the print is much darker than the base color, then this is an overprint fabric.
2. Discharge printing Discharge printing is carried out in two steps. The first step is to dye the fabric into a single color, and the second step is to print the pattern on the fabric. The printing paste in the second step contains a strong bleaching agent that can destroy the background dye, so this method can produce a pattern of blue and white dots. This process is called whitening.
When the bleaching agent is mixed with the dyes that do not react with it in the same color paste (Vat dyes belong to this type), color pull printing can be carried out. Therefore, when a suitable yellow dye (such as vat dye) is mixed with a colored bleach, a pattern of yellow dots can be printed on a blue-backed fabric.
Because the background color of discharge printing is first dyed by piece dyeing, if the same background color is printed on the ground, the color of the background color is much richer and darker. This is the main purpose of using discharge printing. Discharge printed fabrics can be printed by roller printing and screen printing, but not by thermal transfer printing. Because of the high production costs of discharge fabrics compared to direct printing, the use of the required reducing agent must also be controlled with great care and accuracy. Fabrics printed in this way have better sales and higher prices. Occasionally, the reducing agents used in this process can cause damage or destruction of the fabric at the printed pattern. If the color of the front and back of the fabric is the same (because it is piece dyeing), and the pattern is white or a color different from the background color, it can be confirmed that it is a discharge printing fabric.
3. Anti-dye printing Anti-dye printing includes two-stage processes:
(1) Printing chemicals or waxy resins that can prevent or prevent dyes from penetrating into the fabric on white fabrics;
(2) Piece dyed fabrics. The purpose is to dye the base color to bring out the white pattern. Note that the results are the same as for discharge printed fabrics, however the method to achieve this result is the opposite of that of discharge printing. The application of anti-dye printing method is not universal, and it is generally used when the background color cannot be discharged. Compared to the mass production basis, most resist printing is achieved by methods such as handicraft or hand printing (such as wax resist printing). Because discharge printing and resist printing produce the same printing effect, it is often impossible to identify them by naked eye observation.
4. Pigment printing The use of pigments instead of dyes to produce printed cloth has become so widespread that it has begun to be regarded as an independent printing method. Pigment printing is direct printing with pigments, and the process is usually called dry printing to distinguish it from wet printing (or dye printing). By comparing the difference in hardness between the printed and unprinted parts of the same fabric, pigment printing and dye printing can be distinguished. The paint-printed area feels a little harder and maybe thicker than the unprinted area. If the fabric is printed with dye, there is no significant difference in hardness between the printed and unprinted parts.
Dark paint prints are likely to feel harder and less flexible than light or pale colors. When inspecting a piece of fabric for the presence of a paint print, be sure to check all the colours, as both dyes and paints may be present on the same piece of fabric. White paint is also used for printing, this factor should not be ignored. Pigment printing is the cheapest printing method in printing production, because the printing of pigments is relatively simple, requires the least process, and usually does not require steaming and washing.
Paints are available in bright, rich colors and can be used on all textile fibers. Their light fastness and dry cleaning fastness are good or even excellent, so they are widely used in upholstery fabrics, curtain fabrics and clothing fabrics that require dry cleaning. In addition, the paint produced little color difference between different batches of fabric, and the coverage of the base color was also very good when overprinting.
Special printing
The basic method of printing (as mentioned above) is to print patterns on the fabric, and each color in the pattern adopts the printing and dyeing method. Special printing belongs to the second category. The reason for this classification is that this type of method can Obtain special printing effects, or it is not widely used because of high process costs.
1. Floor printing The background color of floor printing is obtained by printing instead of piece dyeing. Usually in the printing process, the color of the base color and the pattern are printed on the white cloth. Sometimes all-over prints are designed to mimic discharge or resist prints, which are more expensive to produce, but the different prints are easily discernible from the reverse side of the fabric. The ground color of the floor-to-ceiling print is lighter on the reverse side; because the fabric is first piece-dyed, the front and back sides of the discharge or resist print are the same color.
The problem with floor-to-ceiling printing is that sometimes a large area of the base color cannot be covered by dark colors. When this problem occurs, carefully check the pattern on the ground and find some dull spots. This phenomenon is basically caused by water washing and not due to the amount of dye coverage.
High-quality allover printed fabrics produced under strict process conditions will not have these phenomena. This phenomenon cannot occur when screen printing is used for full-floor printing, because the color paste is applied by scraping, rather than being rolled in like roller printing. Pigmented all over printed fabrics usually feel very hard.
2. Flocking printing Flocking printing is a printing method in which fiber fluff (about 1/10-1/4 inch) called fiber linter is adhered to the surface of the fabric according to a specific pattern. The process is a two-stage process. First, a pattern is printed on the fabric using adhesives instead of dyes or paints. The linters are then bonded to the fabric. part. There are two methods of adhering linters to fabric surfaces: mechanical flocking and electrostatic flocking. In mechanical flocking, the fiber linters are screened onto the fabric as it passes through the flocking chamber in an open width.
The machine vibrates the fabric while stirring, and the fiber linters are randomly placed into the fabric. In electrostatic flocking, static electricity is applied to the fiber linters, and as a result, almost all fibers are oriented upright when adhered to the fabric. Compared with mechanical flocking, electrostatic flocking is slower and more expensive, but can produce a more uniform and denser flocking effect. The fibers used for electrostatic flocking include all fibers used in actual production, including viscose fibers. The two most common are nylon and nylon.
In most cases, linter fibers are dyed before being transplanted into fabrics. The ability of flocked fabrics to withstand dry cleaning and/or washing depends on the nature of the adhesive. Many high-quality adhesives used in fabric processing operations have excellent fastness to washing, dry cleaning, or both. Since not all adhesives can withstand any type of cleaning, it is necessary to verify which cleaning method is suitable for any particular flocked fabric.
3. Warp printing Warp printing refers to printing the warp of the fabric before weaving, and then weaving it together with the plain weft (usually white) into the fabric, but sometimes the color of the weft and the printed warp are in great contrast. The result is a soft shadowy, even blurred pattern effect on the fabric. Warp print production requires care and meticulousness, so this printed fabric is almost only found on high-end fabrics, with the exception of fabrics woven from fibers that can be printed by heat transfer. With the development of warp thermal transfer printing method, the cost of warp printing has been greatly reduced. Warp printing can be identified by drawing the warp and weft yarns of the fabric, because only the warp yarns have the color of the pattern, while the weft yarns are white or plain. It is also possible to print a warp-like print effect, but this is easy to tell because the color of the pattern is present on both the warp and weft.
4. Burnt-out print
Burnt-out printing refers to the printing of chemical substances that can destroy the fibrous tissue on the pattern. As a result, holes are created where the chemicals come in contact with the fabric. Fake mesh embroidery fabrics can be obtained by printing with 2 or 3 rolls, one roll contains damaging chemicals and the other rolls print the stitches that imitate the embroidery.
These fabrics are used for the raw edges of inexpensive summer blouses and cotton lingerie. The edges of the holes in calico are always subject to premature wear, so this fabric has poor durability. Another type of burnt-out printing is that its fabric is made of blended yarn, core yarn, or an interwoven fabric of two or more fibers. Chemicals can destroy one fiber (cellulose), leaving the other undamaged. fiber. This printing method can produce many special and interesting printed fabrics.
The fabric can be made of viscose/polyester 50/50 blended yarn. When burnt-out printing, the viscose fiber part disappears (rots away), leaving the polyester fiber undamaged. As a result, only the printed part remains. Under the polyester yarn, the unprinted part shows the original sample of polyester/viscose blended yarn
5. Double-sided printing
Double-sided printing is printing on both sides of the fabric to obtain a fabric with a double-sided effect, similar in appearance to packaging fabrics with coordinated patterns printed on both sides. End uses are limited to double-sided linens, tablecloths, lined or double-sided jackets and shirts.
6. Special prints Special prints are prints with two or more unique patterns, each printed on a different area of the fabric, so each pattern will be located in a specific location on the garment. For example, a costume designer would design a blouse with blue and white dots on the front and back, and the same blue and white sleeves, but with a striped pattern. In this case, the clothing designer works with the fabric designer to design both dots and stripes on the same roll. The layout of the print positions and the number of fabric yards required for each pattern element must be carefully arranged to optimize fabric utilization without excessive waste. Another kind of special printing is to print on the garments that have been cut, such as bags, collars, so it can create many different and unique clothing patterns. Parts can be printed by hand or heat transfer.