Difficulty: Easy & Basic
Open-width fabric travels back and forth between two rollers through dye liquor. Identify the machine.
A Jigger
B Package machine
C Winch
D Hank machine
Answer: A. Jigger. The jigger reverses fabric travel between two rollers, taking it through the liquor in open width.
What charge characterizes acid dye ions in solution?
A Alternating equally
B Positive
C Always neutral
D Negative
Answer: D. Negative. Acid dyes have anionic groups, such as sulfonates, that carry negative charge in solution.
In a spectrophotometric shade check, using the same illuminant and observer settings makes which result comparable?
A Dry fabric mass
B Calculated colour coordinates
C Warp ends count
D Dye bath volume
Answer: B. Calculated colour coordinates. Colour coordinates depend on the stated illuminant and observer functions, so those settings should match.
Package dyeing requires liquor to pass through the yarn winding. What supports the yarn?
A On perforated tubes
B Across a knitting bed
C On solid steel drums
D Inside a woven seam
Answer: A. On perforated tubes. Yarn is wound on perforated tubes so liquor can be pumped through the package.
Why is a dispersing agent used with a poorly soluble dye?
A Destroy the fibre surface
B Create cotton yarn twist
C Replace all dye molecules
D Limit particle aggregation
Answer: D. Limit particle aggregation. Maintaining fine particles in dispersion helps the dye remain available for application.
As the pH falls in a wool acid-dye bath, suitable amino sites take on what charge?
A Negative
B Alternating polarity
C Positive
D No charge always
Answer: C. Positive. Amino groups can accept protons, giving positive sites that interact with anionic acid dyes.
What is the purpose of reversing liquor direction in package dyeing?
A Improve penetration uniformity
B Make yarn twist alternate
C Decrease all bath volume
D Add colour to the tubes
Answer: A. Improve penetration uniformity. Alternating flow helps reduce inside-to-outside shade differences in wound packages.
Before entering a continuous dye reaction stage, what does a padding nip do?
A Cuts fabric edges
B Adds twist to yarn
C Measures fabric strength
D Controls retained liquor
Answer: D. Controls retained liquor. Squeezing the fabric between rollers controls the amount of liquor carried forward.
Inside a jet dyeing machine, what helps carry fabric in rope form?
A Dye liquor flow
B Dry heating plates
C A spinning spindle
D A fixed reed
Answer: A. Dye liquor flow. A fast stream of circulating liquor propels the fabric around the machine.
What distinguishes the colour appearance of a heather yarn made from differently stock-dyed fibres?
A Solid colour on all fibres
B Uniform surface pigment film
C Blended tones within yarn
D Only fibre-free outer coating
Answer: C. Blended tones within yarn. Differently coloured fibres are blended before spinning, creating visible small-scale colour variation.
Why is the temperature often increased at a controlled rate during exhaust dyeing?
A Reduce all water to vapour
B Set the fabric warp count
C Calibrate the pH scale
D Manage dye uptake rate
Answer: D. Manage dye uptake rate. A controlled ramp can limit sudden uptake and allow more uniform dye penetration.
Identify the auxiliary used to control rapid strike so more uniform shade can develop.
A Needle oil
B Bleaching powder
C Leveling agent
D Warp size
Answer: C. Leveling agent. A leveling agent moderates uptake or helps dye redistribute among sites on the fibre.
Pad–steam fixation uses what heating medium?
A Dry ice
B Liquid nitrogen
C Steam
D Cold air
Answer: C. Steam. Steam supplies heat and moisture for fixation after padding.
Why should package winding density be reasonably uniform?
A Raise dye weight automatically
B Allow even liquor flow
C Reduce fibre length by half
D Prevent all package movement
Answer: B. Allow even liquor flow. High or uneven density can restrict flow in some regions, producing shade differences.
To correct excess surface colour from disperse dyeing, what does reduction clearing target?
A Fibre polymer chains
B Residual surface dye
C Pigment binder in prints
D The warp yarn size
Answer: B. Residual surface dye. Reduction clearing helps remove disperse dye residues on the fibre surface after dyeing.
Certain natural dyes give different hues on the same fibre when the binding salt changes. Which application aid is being varied?
A Warp size
B Foam breaker
C Dispersing carrier gas
D Mordant
Answer: D. Mordant. Some dyes form colour complexes with mordants. The identity of the mordant can change the shade.
If coloured material transfers to a dry white cloth under rubbing, which performance property is affected?
A Thermal insulation
B Yarn fineness
C Crocking fastness
D Light fastness
Answer: C. Crocking fastness. Crocking assesses colour transfer from a textile to another surface by rubbing.
In pad–batch dyeing, why is padded fabric held for a period before washing?
A Rewind loose fibres
B Allow time for fixation
C Remove dry starch first
D Set knitting gauge
Answer: B. Allow time for fixation. Holding the padded fabric provides time for dye to react under the specified process conditions.
Which term describes a dye’s tendency to transfer from bath to fibre under specified conditions?
A Affinity
B Moisture regain
C Areal density
D Yarn crimp
Answer: A. Affinity. Affinity describes the preference of dye for the fibre relative to the bath.
Polyester and cotton in a blend commonly require what dye selection?
A One direct dye always
B Basic dyes for both
C Dyes suited to each fibre
D Acid dyes for both
Answer: C. Dyes suited to each fibre. The fibres differ chemically. Disperse dyes suit polyester and compatible cellulose dyes are used for cotton.
Yarn dyed in loose loops is in which form?
A Hanks
B Garment bundles
C Warp beams
D Piece rolls
Answer: A. Hanks. Hank or skein dyeing treats yarn wound into loose loops.
In a thermosol route for polyester, which stage drives disperse dye into the fibre?
A Acid wool neutralization
B Oxidation of leuco dye
C Cold water rinsing
D High-temperature dry heating
Answer: D. High-temperature dry heating. The dry heat stage increases dye mobility and promotes diffusion into the polyester.
For shade approval, why is an approved reference swatch retained?
A Clean dyed bath liquor
B Compare production against it
C Determine warp-beam diameter
D Measure plant steam pressure
Answer: B. Compare production against it. The approved swatch provides a physical colour reference for evaluating production lots.
When dye is taken up much faster at some points than others, which appearance fault can develop?
A Higher yarn twist
B Uneven shade
C Needle breakage
D Wrong fabric length
Answer: B. Uneven shade. Local uptake differences can produce darker and lighter regions within the same material.
Which machine is suited to dyeing an open-width fabric wound onto a perforated cylinder as liquor passes through it?
A Jigger dyeing machine
B Loose stock dyeing machine
C Beam dyeing machine
D Winch dyeing machine
Answer: C. Beam dyeing machine. A beam dyeing machine can circulate liquor through the fabric wound onto a perforated beam.