19 questions about textile
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chapter19rapa1.pptChapter 19
Dyeing and Printing
T101
Survey of the Textile Industry
Christina Rapa
215-490-7999
- Important product characteristic
- Goal: produce appealing, level, fast color on product at reasonable price with good performance and minimal environmental impact, sustainable
- Complex: difficult to get color on fabric in uniform appearance (level) that will not fade, bleed, or alter
Color
- Complex phenomenon:
- Physics of light, chemistry of colored objects, biology of the eye, behavioral sciences, & aesthetics
- Metamerism: a color matches with one light source, but not with any other light source
- Bezold effect: when two or more colors merge into one new color, i.e., small scale print or yarn dyed fabric viewed from a distance
Color Theory
- Assign numerical values to a color
- Used to match color & sort shades
- Lab dip: sample prepared by dyehouse, used by creative team to determine if color match has been achieved
- Color matching developing a formula to reproduce a color
- Shade sorting: grouping of colors by a manufacturer so that all fabric of one color match
Color Measurement
- Wash-off: rinsing step used to remove excess dye or other material from a fabric
- Wash-down: color loss that occurs over time as the textile product is laundered or dry cleaned
Color Terms
General term describing materials used to color textiles
- Pigment
- Insoluble inorganic compound glued or bonded onto fiber surface
- No affinity for fiber
- White & colored pigments
Colorants
Ingredients in Pigment Paste
- Opacifier:
- produces good covering power
- various lusters
- Thickener
- prevents migration of paste
- Thinner
- keeps paste semi-fluid
- Antibleeding agent
- eliminates halo effect
- Pigment
- adds color
- Softener
- maintains soft hand of fabric
- Dye:
- organic compound, water or other carrier soluble
- has affinity for fiber (forms bond with fiber)
- Fiber specific:
- fiber chemistry restricts dyes that can be used
- only certain combinations of dye class & fiber type work
- High color strength
- Fastness varies by dye & dye class
Colorants
- Dye components
- Chromophore: colored part of molecule
- Auxochrome: alters color, provides bonding & solubility sites
- Acidic
- Basic
Colorants
- Acid (anionic):
- wool, silk, nylon; some rayon, acrylic, & polyester;
- bright colors, poor wet fastness,
- may have poor light fastness
- Azoic:
- cotton, some polyester;
- bright shades, good fastness to light & water;
- poor crocking; water insoluble; solubility cycle dye
Dye Classes
Wool
Silk
Nylon
- Cationic (basic):
- acrylic, wool; some polyester & nylon
- good fastness on synthetics, but poor on natural fibers
- bright colors
- Disperse: Polyester
- synthetics; good fastness;
- may fume fade; needs special equipment
Dye Classifications
Polyester
Acrylic
- Developed direct (direct dye + metal (mordant)):
- cellulosic fibers
- good light fastness
- fair wash fastness, duller colors
- Direct:
- cellulosic fibers; similar to above, but brighter colors;
- large, planar molecules; moderate wet fastness
- most commercially important class
- Fluorescent:
- most fibers; dye absorbs energy at one wavelength,
- reemits at another wavelength; whitens;
- used in finishing & home laundry
Dye Classifications
Cotton
Most fibers
- Mordant dyes (acid dye + metal):
- wool, silk, nylon
- some rayon, acrylic, & polyester
- duller colors; excellent fastness
- Natural dyes:
- minor dye class
- best on protein fibers, nylon, and cellulosics
- renewable & sustainable
- from plant, animal, & mineral sources
- used for apparel & interiors
- limited colors & availability
Dye Classifications
- Reactive:
- natural fibers; bright, pure colors
- good to excellent fastness
- Sulfur:
- cotton: insoluble in water
- solubility cycle dye; difficult process;
- dull colors; good fastness; tender fabric
- used for bottom weight goods
- Vat:
- cotton; insoluble in water; solubility cycle dye
- difficult process; dull colors; good fastness
- incomplete color range; used for bottom weight goods
Dye Classifications
Cotton
Cotton
Cotton
- Mass pigmentation (solution dyed, dope dyed):
- add colored pigments to spinning solution
- color integral part of fiber
- Gel dyeing:
- color incorporated before fiber coagulates
Stage of Dyeing: Fiber Stage
Synthetics: Specialty Fibers
- Stock or fiber dyeing:
- fibers dyed before yarn processing
- heather effect
- Top dyeing:
- difficult to distinguish between top & stock dyeing
Fiber Stage
Wool Stock Dyeing
- Stripes, plaids, or structural design fabrics
- More expensive than piece dyeing (solid colors usually piece or product dyed, not yarn or fiber dyed)
Stage of Dyeing: Yarn Stage
Swatch Kit - Fiber & Yarn Dyed
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- Rope Dyeing: Indigo dye / Denim Jeans
- Warp yarns are dyed in “ropes” before slashed onto warp beam
Yarn Dyeing
- More likely to see stripe parallel to warp yarns in woven fabric (easier to dress loom) or parallel to course in knit fabric (change color at yarn feed for circular or flat bed knits)
Yarn Dyeing
Yarn Dyeing
- Dyed in fabric stage:
- usually solid color
- Cross dyeing:
- fibers of different dye receptivity (modification or generic class) for different colors
- Union dyeing:
- fibers of different dye receptivity (modification or generic class) for single uniform color
Fabric Dyeing: Piece Dyed
Wool
Cotton
- Beck, reel, or winch dyeing:
- continuously immerse fabric in dyebath
Methods of Dyeing:
Fabric Dyeing
- Jig dyeing:
- large runs of fabric passed through dyebath several times
Methods of Dyeing:
Fabric Dyeing
- Pad dyeing:
- in bath in open width; dye forced into fabric (30-300 yd/min)
Methods of Dyeing:
Fabric Dyeing
- Batch or exhaust dyeing:
- textile circulated through dyebath
- Package dyeing:
- dyebath forced through textile;
- usually yarns, but some fiber & fabric
Methods of Dyeing
Textile & dyebath circulated
- Jet dyeing:
- similar to beck dyeing; delicate fabrics; 215-870 yd/min
- Continuous machine or range:
- large lots of goods; one or two bath processes for union and cross dyeing; Thermosol process
Combination Dyeing
- Product (or garment) stage
- Color added after product is cut & sewn
- Found in socks, hosiery, tee shirts, jackets, slacks, towels, etc.
- Problems with leveling, difference in components, poor penetration, dimensional changes; requires well prepared gray goods
Garment Dyeing
- Paddle machine, rotary drum, or tumbler:
- product dyeing; abrasive & chemical washes
Combination Dyeing
Color prevented from entering fabric in specific areas when piece or yarn dyed
- Batik: hot wax on fabric in design; set; piece dyed; wax removed; price related to quality & colors
Resist Dye: Batik
- Tie-dyed:
- yarn or fabric wrapped to prevent dye penetration during piece dyeing; thread removed after dyeing
Resist Dye: Tie Dye
- Ikat:
- yarn tied to prevent dye penetration, dyed, woven; single or double ikat
Resist Dye: Ikat .
- Localized application of color to fabric’s surface
- Paste made of dyes (not pigments): wet print
- Paste made of pigments: dry print; adhesive
(may change fabric hand)
Printing
- Direct print: color applied directly to desired location
- Block: hand process; carved wood block pressed in dye paste, stamped onto fabric; different block for each color
Printing
- Roller etched with design
- picks up paste & presses it onto fabric as fabric passes between rollers
- different roller for each color up to 16 colors
Direct Roller Print .
- Discharge print: Piece dyed fabric
- Color removed by printing with bleach paste
- Usually dark ground
- Discharged areas may be tender with poor aging resistance
- Trace of dark ground may appear on technical back in print area or dark areas surrounding print are same color face & back (piece dyed, then discharged)
Discharge Printing
Discharge
Direct
- Warp yarns printed before weaving; hazy pattern
Warp Print
- Screen print: screens etched with design control location of color; one screen/color
- Flat screen: screen is flat; slower; for shorter yardages
Screen Printing
Fabric Swatch Kit #83
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Screen Printing: Flat Screen
- Rotary screen:
- screen in cylinder form, faster
- most common method to print yardage
Screen Printing: Rotary
Digital (ink jet) print: color applied using ink jet printer
Carpets & textile samples
Digital Printing
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- Heat transfer print:
- print design on paper with disperse sublimable dyes (with heat, dye evaporates)
- fabric & design on paper are placed in close contact, heated, dye transfers
Heat Transfer Printing
Swatch Kit # 85 / 86
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Fabric Swatch kit #82 / 83 / 84
- Foil print:
- special adhesive applied to fabric
- fabric dyed and partially cured
- foil transferred by heat transfer press
- bonds only where adhesive has been applied
- Stencil print:
- precursor of screen print
- paper or metal pattern
- brush or spray color on
Foil / Stencil Printing
- Electrostatic print
- powdered dye heat-fixed to fabric surface
- dye location controlled by screens
- Differential print
- screen print on carpet with fibers of different dye affinity (cross dye)
Other Printing Methods
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- Colorfastness
- related to chemistry of fibers, dyes, & pigments; penetration, & fixation
- Bleeding
- loss of color in water or other solutions, may color other fabrics present
- Migration
- color movement to adjacent areas or fabrics
Color Problems
- Crocking
- color transfer to another fabric from rubbing together
- Fading
- color loss due to perspiration, gas fumes, sunlight
- dyes degraded
Color Problems
- Tendering
- fabric strength loss due to reaction of dye & fiber
- caused by heat, light, atmospheric contamination, etc.
Color Problems
- Frosting
- colored portion of fabric lost by abrasion (due to poor dye penetration)
- Out-of-register
- print color overlaps or misses desired areas
Color Problems
- Chapters 15, 19
- Found on Blackboard
- Print out
- Hand-write answers
- 10% deduction for each day late
Test #5 – Due Tuesday, Apr 22nd
