A brief discussion on the reasons why white cloth turns yellow
1 It is recommended to use the same high temperature oxygen bleaching process. For example, 110 degrees/20 minutes to improve the utilization efficiency of hydrogen peroxide.
2 It is recommended to use the two-bath method, boiling and bleaching first before whitening, and hot washing before whitening to clean the alkali, which is also good for improving the whiteness.
3 For bleaching, pickling is not recommended, because most whitening agents are resistant to alkali and not acid, and will easily change color after pickling. If you don’t believe it, give it a try.
4 The key is to choose a softener that can withstand high-temperature drying. Most softeners will turn yellow seriously after drying. To filter, change the color before and after softening.
5. The influence of water color. Generally speaking, if the color is less than 3 degrees, there is no problem in dyeing white yarn. Processing at 3-5 degrees may improve it. If it is more than 5 degrees, stop the work quickly. Otherwise, the more white yarn you dye, the more painful it will be. sharp.
It is recommended to detect the following issues:
1. The residual amount of hydrogen peroxide and alkali in the yarn after bleaching;
2. Optimal dosage and high temperature resistance of whitening agent;
3. Yellowing of softener;
4. The content of metal ions, especially iron ions, in the water.
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