Textile Coloration-I paper (WPE 301) from BUTEX's 2024 Level-3 Term-I finals. Questions include salt saving calculations with liquor ratio changes, reactive dye mechanisms with hydrolysis, basic dye classification, and vat dyeing process curves.
Level-3 Term-I, Final Exám-2024
Subject: Textile Coloration-I (Code: WPE 301)
Time: 3.0 Hrs. Full Marks: 72
(Use separate answer script for Part: A and Part: B)
(All parts of a question must be answered consecutively)
Part: A
(Answer any three questions)
1. (a) Define the terms: affinity, substantivity, and sorption.
(b) Differentiate among chromophore, chromogen and auxochrome.
(c) Suppose 20 g/L sodium chloride is needed for dyeing 1.25 tons of cotton single jersey fabric with 1% o.w.f. shade of reactive dye. If the liquor ratio is reduced from 8:1 to 6:1, how much salt could be saved?
(d) Write a short note on cross dyeing.
[3+3+3+3=12]
2. (a) Why are direct dyes substantive to cotton fabric?
(b) The washing fastness of direct dyes can be improved by treating them with a metal salt; justify the statement.
(c) Illustrate a reactive dye, mentioning different parts of the dye.
(d) What is the hydrolysis of reactive dye? Describe the dyeing mechanism of reactive dye.
[3+3+1+5=12]
3. (a) What is Dosing? Classify basic dyes based on chemical structure, mentioning at least one example.