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Questions and Answers
What must vat dyes be reduced to before being applied to cotton or rayon fiber?
What must vat dyes be reduced to before being applied to cotton or rayon fiber?
- Leuco form in an alkaline solution of sodium hydrosulfite (correct)
- Oxidized form in a neutral solution
- Direct form in an acidic solution
- Hydrophilic form in a water-based solution
What fixes the vat dye strongly on the fiber, resulting in excellent wash-fastness and light-fastness?
What fixes the vat dye strongly on the fiber, resulting in excellent wash-fastness and light-fastness?
- Steam treatment
- Air oxidation (correct)
- Chemical bleaching
- UV exposure
What is the main use of vat dyes in terms of fiber dyeing?
What is the main use of vat dyes in terms of fiber dyeing?
- Protein fiber dyeing without pH control
- Synthetic fiber dyeing
- Cellulose fiber dyeing (correct)
- Wool fiber dyeing
What is the washing fastness rating of vat dye?
What is the washing fastness rating of vat dye?
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What is the classification of vat dyes according to chemical structures?
What is the classification of vat dyes according to chemical structures?
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Vat dyes are soluble in water.
Vat dyes are soluble in water.
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Vat dyes must be reduced to the leuco form before being applied to cotton or rayon fiber.
Vat dyes must be reduced to the leuco form before being applied to cotton or rayon fiber.
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Rubbing fastness of vat dyes is good.
Rubbing fastness of vat dyes is good.
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Vat dyes are inexpensive in price.
Vat dyes are inexpensive in price.
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Vat dyes are mainly used for protein fiber dyeing.
Vat dyes are mainly used for protein fiber dyeing.
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