． Loose hair is dyed with weak acid dyes, and the color of the inner and outer layers or upper and lower parts of the fiber in the vat is uneven. Sometimes some fibers are not colored and white spots appear. How to solve this problem?
Answer: When loose wool is dyed, the installation is very important. If the loose wool installation is unevenly tight, or some fibers are felted, agglomerated, and tightly entangled, it will make it difficult for the dye solution to penetrate, hinder the uniform circulation of the dye solution, and cause a short circuit. At this time, it is very easy to It is easy to cause uneven color in the inner and outer layers or the upper and lower parts. Sometimes some fibers are not colored, causing white spots. Sometimes the power of the dye liquor circulation pump is insufficient and the belt is loose, which will prevent the dye liquor from evenly permeating and circulating in all parts of the dye vat. This requires sufficient power of the dye liquor circulation pump during dyeing to ensure smooth circulation of the dye liquor in the upper, middle and lower parts. Sometimes improper selection of dyes can also cause uneven color or severe color blooming. For weakly acidic dyes, some dyeing rates are faster before 70°C, and some are faster after 70°C. Pay attention when matching colors. Weak acid deep blue GR, 5R dyes and other weak acid dyes should not be used together. The pH value of the dye bath should be strictly controlled between 4 and 6. The pH value is low, the dyeing speed is fast, and color flowers are easily produced. The pH value is too high, which affects the leveling effect and can also cause color flowers. Weak acid brilliant blue 7BF is prone to uneven coloring. Pay attention to the heating speed. National hair will color faster at 60-70℃ (outer hair at 70-80℃). The maximum dyeing temperature of this dye should be controlled at 98°C to avoid black sesame-like particles produced by violent boiling dyeing and adhering to the fiber and dye vat. When dyeing for color matching, you should choose dyes with similar dyeing rates, dye transfer properties, dye bath pH values, solubility, etc. You should avoid using different types and different performance dyes for dyeing. For example, weak acid deep blue GR and 5R color quickly at 75°C and can be kept warm for 15 to 30 minutes before raising the temperature for coloring. For dyes with fast dyeing speed, if the coloring is uneven, it is difficult to improve it even by boiling dyeing. Such dyes should strictly control the heating speed and use slow dyeing method to dye evenly.
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