Printing is essentially a form of localized dyeing. Therefore, when printing and dyeing use the same dye, the chemical auxiliaries used are basically similar in nature, the principles of dye application and fixation are basically the same, and the final colorfastness on the fiber is also basically the same.
I. Differences between Dyeing and Printing PART 01
1. Dyeing usually does not add or only adds a small amount of thickening paste; while printing paste must contain a large amount of thickening paste to prevent the pattern from spreading and the outline from becoming blurred, and to prevent the color from shifting during drying.
2. When dyeing, the dye concentration is low, so no need additional solubilizing agent. However, printing pastes have a high dye concentration and require the addition of a large amount of paste, which makes the dye difficult to dissolve. Therefore, more solubilizing agents, such as urea, alcohol, and dissolving salt B, are needed.
3. During dyeing (especially immersion dyeing), the fabric is soaked in the dye bath for a relatively long time, allowing the dye to slowly and fully penetrate into the fibers to complete the coloring process. During printing, the paste in the dye paste forms a film after drying, which hinders the dye from penetrating the fibers. Therefore, post-treatments such as steaming and baking are necessary to accelerate the diffusion of the dye and help it penetrate into the fibers.
4. Dyeing generally uses only one type of dye for color matching (except when dyeing blended fabrics). Printing, on the other hand, often uses different types of dyes together, or even in the same color paste. In addition, there are many special processes such as discharge dyeing, resist dyeing, and resist printing, so the design of printing processes is different from that of dyeing.
5. Because printed fabrics often have white backgrounds for printing, or require processes like whitening or anti-whitening that require a clean base color, the whiteness requirements after pretreatment of the fabric are very high, basically reaching the whiteness of bleached fabric. Dyed fabrics, on the other hand, are dyed as a whole, so the whiteness requirements for the raw fabric itself are relatively lower.
6. For dyeing, the greige fabric only needs to have good water absorption (capillary effect) to allow the dye to slowly penetrate and diffuse into the fiber. However, the printing process is extremely fast, with printing and drying completed almost continuously within seconds. It also requires uniform color, clear outlines, and complete, unbroken lines. Therefore, the greige fabric for printing must not only have good water absorption but also uniform and rapid instantaneous water absorption capacity to ensure that the dye is quickly and accurately absorbed by the fabric during printing, resulting in a complete and clear pattern.
II. Differences between Dyeing and Printing PART 02
The differences between dyeing and printing are as follows:
① Printing provides better coverage for imperfections on the fabric than dyeing.
② Printed fabrics have particularly strict requirements regarding weft skew.
③ Even with the same type of dye, the requirements for dyeing and printing may differ.
④ Dyeing and printing have different requirements for the pretreatment of semi-finished products (e.g., whiteness, absorbency).
⑤ Dye liquor contains little or no thickening agent, while printing pastes require more thickening agent.
⑥ During dyeing, the dye can fully penetrate and diffuse; during printing, the dye does not penetrate easily and requires steaming or baking.
⑦ Dyes in dye liquor are easily soluble and generally do not require co-solvents; printing pastes require more co-solvents.
⑧ Dyeing rarely uses different types of dyes in combination, while printing often uses multiple different types of dyes.
2. Dyeing and printing share the following three similarities:
① For the same fiber, dyeing and printing with the same dye will result in the same colorfastness.
② The chemical auxiliaries used in both processes are similar in nature.
③ The basic principles of dyeing and fixing are the same.
