The FAQ about Substitute Alkali (Production Practice)
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1.Which kinds of fabric can be dyed in substitute alkali? And which color can be dyed into?
Answer: it can be used for dyeing cotton fabric. And it can be used to dye any color of the cotton fabric.
2.How can we do if the discoloration has appeared on the fabric when we dye using substitute alkali?
Answer: The reasons for discoloration is various. And the following three aspects can be used in checking alkali.
Firstly: Check the weight of the substitute is proper or not. The Alkali substitute is high concentration alkali. If there is a mistake on the fabric, the discoloration will occur.
Secondly: check the holding times is enough or not. In general conditions, the holding time for bright color fabric is about 45 mins. And 60-70 mins for dark color. If the hold time is not enough, the dyes will not be fixed completely. After soaping, the color will become light than expected.
Thirdly: Check the adding of sodium carbonate or not. Because the substitute alkali is high concentration alkali. It has high requirement on the dyer’s technical level. In order to keep the quality of fabric, we should add 10% sodium carbonate in the process of dyeing bright fabric. And 15% for dark fabric.
3. What should we do when the dyeing defect occurs?
Answer: the reason for dyeing defect is various. Such as the incomplete preliminary treatment. Adding leveling agent or not for different structure fabric. The another important reason is too fast temperature rise. If too fast, the partial increase in the vat will cause dyeing defect. Normally, 1℃ in one minute.
4. Is there any influence on the fastness of the fabric if we using substitute alkali?
Answer: no. It is similar of the fastness of the fabric for substitute alkali and sodium carbonate.
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