GK for Dyeing
What is singening?Singeing: Singeing
is a process carried out to remove loose hairy fibre protruding from the surface of the cloth/yarn
by burning them.
Why singeing is necessary?
Ø To obtain smooth surface
Ø To increase luster
Ø Optical levelness of dyeing &
clean out of printing design.
Types of singeing m/c ( plate,
roller, gas)
1. Plate singeing m/c
2. Roller singeing m/c
3. Gas singeing m/c
Desizing: Desizing
is the first step of textile wet processing finishing technology employed to
remove sizing material from the fabric.
Why Desizing is necessary?
Ø To remove starch from the fabric.
Ø To increase absorbency of the fabric.
Ø To increase luster of dyed & printed fabric.
Ø For perfect action of scouring & bleaching.
Give some example of common sizes
1. Starch: Corn, photo, Sago.
2. Natural gun: Tragacanth, Locust-beam
etc.
3. Protein: Glue, gelatin.
4. Synthetic sizing agent: PVA, PAN, CMC
(Carboxy methyl cellulose).
5. Additives: Deformer, Tallow, Oil
& greases.
6. Enzyme: Enzyme
is one kind of bio-catalyst. Its molecular weight is high & they are
living organism.
The action of enzyme is controlled by-
¨ Temp
¨ Concentration
¨ Time
¨ PH of the solution
Problem by size material-
¨ Stiffens the fabric handle
¨ Reduce the absorbency of fabric
¨ Reduce the absorbency chemical
¨ Size may absorbed by chemical
Starch: Made
by amylase & amylosepectin.
α-amylase:
Which attack the chain at random, so degree of polymerization of starch is
rapidly reduced.
β-amylase:
Which successively remove the terminal maltose from reducing ending polymer
chain is shortened.
Bleaching is not necessary for which type of fabric-
v For dark shade fabric such as red,
black & navy blue.
v Man made fabrics.
Bleaching is done for-
v White, light & medium shade
fabric
What % of fabric strength after scouring ?
v 20-30%
Caustic Soda:
Neutralize acidic material
Saponity glycerides, wax & Oil.
Sequestering agent: Deactivate metal ions, reduce hardness of water.
Wetting agent & detergent: To reduce surface tension, emulsity oil, fats, waxes.
Oxidizing bleaching agent:-
O3one (O3) H2O2 Ca (OCl)2 K2Cr2o7 KMnO4
Reducing bleaching agent:-
Zinc dust (Zn) Stannous chloride (SnCl2) Ferrus Sulphate (FeSO4) Sulphur di-oxide (SO2) Hydrozen Sulphate (H2S)
Shouring: Treating
the fabric with 1% HCl or H2SO4 to remove CaCO3
is known as shouring.
Disadvantage of Ca(OCl)2 : Ca(OCl)2 reacts
with atmosphere CO2 & H2O to give CaCO3 as
white participate CaCO3 deposit on fabric causes harsh feeling &
uneven dyeing. But this is not done in case of Na(OCl).
Na2CO3: To maintain the pH
Why hypochlorite /chlorite bleaching is not used in wool & Silk?
Ans. Hypochlorite/chlorite bleaching is not
used in wool and silk because Cl of hypochlorite reacts with protein and thus
the main bleaching action is not done & fabrics become discolored &
hampered.
PPM: Per
mullion parts of water or mg/l or gm/m3 .
How hardness of H2O is expressed?
Ans. The hardness of water is
expressed by the amount of metal on present in water.
Problem causes by hard water-
Ø Reduce cleaning efficiency
Ø Reduce absorbency & lusture.
Ø Reduce dye diffusion
Ø Uneven dyeing
Soap: Soap is
a metallic salt of a saturated or unsaturated higher fatty acids.
Factors for color vision:
1. Light
2. Substrate
3. Observer
Detergent: A
detergent is compound, or a mixture of compounds, intended to assist cleaning
& acts mainly on the oily films that trap dirt particulars.
Dyes: Dyes are
colored unsaturated organic chemical compounds which are responsible for the
color of dyed & printed textile materials.
Which agent is known as universal bleaching agent?
→Hydrogen per oxide (H2O2)
Ideal pH of fibre after neutralization:
→5.5-6.5
Light: This is
the first element of color perception light is energy.
Textile printing: Textile printing is the most important and versatile of the technologies
used to add design, color & racialist to textile fabrics.
Effects of electrolyte-
Electrolyte
increases exhaustion of dyeing.
Types of vat dyes-
There are two types of vat dyes-
those are below
1. Indigoid
2. Anthraquinion
Classify of hard water: Two types of hard water
1. Temporary 2. Parmament.
Source of hardness:
1. water
2. Fabric
3. Chemical
What is bleaching powder?
Ans. A complex mixtures of calcium
hypochlorite & calcium oxide.
Why H2O2 is called universal bleaching agent?
Ans. All types of fabric are
bleaching in this agent.
Both sides of fabric is signed in which singeing m/c.
→Gas singeing m/c
When signed fabric produce spot?
Ans. If fabric contain ZnCl2
or MgCl2
ZnCl2 +H2O =
ZnO + HCl
HCl + Cellulose = Hydrolysis spot
Which fabric is difficult to operate by gas singeing m/c.
→Synthetic fabric
After Desizing absorbency of the fabric increase or decrease?
→Increase
What are the methods of desizing?
Methods of Desizing
Hydrolytic desizing Oxidative desizing
1. Rot steeping 1. Bromite
desizing
2. Alkali steeping 2.
Chlorite desizing
3. Acid steeping 3.
Ammonium per
sulphate desizing.
What is pancreatic enzyme: The pancreatic enzymes are prepared from the pancreases of
the slaughtered animals.
Trade name: Vivesal, Novotermosol.
What is malt-extract enzyme: These enzymes are obtain by extraction of freshly germinated
barley corn.
Trade name: Diaster, Papidase.
What is bacterial enzyme: Obtain by termination from bacillus substitute which grown
on rice and it break down the stretch into water somble dextrin’s.
Trade name: Rapider, Biolase
After desizing which test is done to ensure the desizing.
At first produce 100cc solution with
KI. I2 and water.
Then some drops of this solution
falls into the sizing material randomly. Then the following incident may occur-
1. Deep blue color –Present of
starch/Not done desizing
2. Violet color—Present partially
degraded starch/desizing is done partially.
3. Brown – Completely degraded
starch/desizing is done complete
What are the forms of
scouring:
(i) Yarn form (ii)
Fabric from
-Hank form -Rope form
(knit)
-Package form -Open width
form (knit, woven)
-Continuous sheets
form (woven)
What are the types of
scouring ?
i)
Batch
process
ii)
Semi-continuous
process
iii)
Continuous
process
Stripping: If
the textile goods become uneven dyeing and unsuitable for using,the color has
to be destroyed. The process is called stripping.
Curing: The
application of heat, usually to polymerase or set remains applied to textile
materials.
Degree of polymerization: The number of monomers or repeating units is one polymer.
More specially, it is the average molecular weight.
Oleophilic: Having
a strong affinity for oie; readily absorbs oil, grease, wax etc.
Primary additive colors-
1. Red
2. Blue
3. Green
Specifying of color-
1. Hue
2. Value
3. Chroma
Azoic dyes are also called -
Ø Naphthol dyes
Ø Ice colors
Ø Developed color
Ø Magic color
Whiteness: The
attribute by which an object color is judged to approach a preferred white.
Buffer: It is
a saturated solution of acid salt or alkali-salt mixture.
Expression of mixtures:
1. w/w-weight to weight
2. w/v-weight to volume
3. v/v-volume to volume
How to prepare 0.1% stock solution:
10 ml or 1 ml of 1% solution need to mix with
90 ml or 9 ml water respectively.
Dyeing Glossary
Absorbency:
The ability of one material to take up another material.
Absorption:
The process of gases or liquids being taken up into the pores of a fiber, yarn,
or fabric.
Acetic acid:
An organic acid (CH3COOH) widely used in textile applications. It is used in
textile wet processing, dyeing and printing, and in the manufacture of
cellulose acetate and cellulose triacetate.
Acetic, anhydride: Anhydrous acetic acid [(CH3CO)2O]. It is used in the acetylation process
in the manufacture of cellulose acetate.
Acetone:
Diemthyl ketone (CH3COOH). One of the most powerful organic solvents. Acetone
dissolves secondary cellulose acetate and other derivatives of cellulose. It is
miscible with water and has a low boiling point(55-56oC)
Acid dyes: An
anionic dye having substantivity for fibers (e.g. Protein, polyamide) which
contain cationic groups usually in acidic or neutral aqueous dyebaths. Acid
dyes are often applied to fabric in organic or inorganic acid dyeing solution.
Acid-dyeable variants: Polymers modified chemically to make them receptive to acid
dyes.
Acidic: A term
describing a material having a pH of less than 7.0 in water.
\Activated
oxygen bleach: A bleaching system comprising an oxygen bleach and a bleach
activator.
Add-on: The
amount of materials applied to a textile is known add-on; it is calculated as
the weight of solids left on a given weight of fabric after impregnation and
drying. The percentage add-on is computed by the formula {(w2-w1) ×100}/ w1;
where w1 is the initial weight of material before impregnation
(wet-out), and w2 is the weight of material after impregnation and
drying.
Additive: A
supplementary material combined with a base material to provide special properties.
Adsorption:
The attraction of gases, liquids or solids to surface areas of textile fibers,
yarns, fabrics or any materials.
Aerobic: A
biological process active only in the presence of oxygen.
Affinity:
Chemical attraction; the tendency of two elements or substances to unite or
Combine together, such as fiber and dyestuff. Affinity is usually expressed in
units of joules (or calories) per mole.
Aftertreatment:
Any treatment done after fabric production. In dyeing, it refers to treating
dyed material in ways to improve properties; in nonwovens, it refers to
finishing processes carried out after a
web has been formed and bonded. Examples are embossing, creping, softening,
printing and dyeing.
Alkaline: A
term used to describe a material having a pH greater than 7.0 in water.
Anaerobic: A
biological process active only in the absence of free oxygen.
Aniline dyes:
Dyes derived chemically from aniline or other coal tar derivatives.
Anionic dye: A
dye dissociates in aqueous dyebath and provide negatively charged colored ion.
Anthraquinone dyes: Dyes that have Anthraquinone as their base and the carbonyl group
(>C=O) as the chromophore. Anthraquinone-based dyes are found in most of the
synthetic dye classes.
Antichlor: A
chemical, such as sodium thiosulfate , used to remove excess chlorine after
bleaching.
Azo dyes: Dyes
characterized by the presence of an azo group (-N=N-) as the chromophore. Azo
dyes are found in many of the synthetic dye classes.
Azoic dyes:
The dyes, produced by interaction of a diazotized amine (azoic diazo component)
and a coupling component (azoic coupling component).
Bacterial Amylase Unit (BAU):
A measure of starch
degradation as shown by the quantity of an enzyme that will dextrinize one
milligram of starch per minute under the specified experimental conditions.
Basic dyes: A
class of positive-ion-carrying dyes known for their brilliant hues. Basic dyes
are composed of large-molecule, water-soluble salts that have a direct affinity
for wool and silk and can be applied to cotton with a mordant.
Batch: A group
of units of products of the same type, structure, colour and finish, class and
composition, manufactured under essentially the same conditions and essentially
at the same time, and submitted at any one time for inspection and testing.
Similar word ‘Lot’.
Bath ratio:
Ratio of bath to fiber as 20:1, 10:1 or 1:20, 1:10
Binder: An
adhesive applied in pigment application to make a bond between fibers and
pigment.
Bleaching: A
process of whitening fibers, yarns, or fabrics by removing the natural and
artificial impurities to obtain clear whites for finished fabric, or in
preparation for dyeing and finishing. The materials may be treated with
chemicals or exposed to sun, air, and moisture.
Carbonizing: A
chemical process for eliminating cellulosic material from, synthetic and wool
or other animal fibers. The material is reacted with sulfuric acid or hydrogen
chloride gas followed by heating. When the material is dry, the carbonized
cellulose material is dust-like and can be removed.
Carrier: A
product added to a dye-bath to promote the dyeing of hydrophobic manufactured
fibers and characterized by affinity for, and ability to swell, the fiber.
Cat-ion: A
positively charged ion.
Cationic dyes:
A dye that dissociates in an acidified, aqueous solution to give a positively
charged colored ion.
Caustic Soda:
The common name for sodium hydroxide(NaOH)
Chrome dye: A
mordant dye capable of forming a chelate complex with a chromium ion.
CIE:
Commission internationaly de I’Eclairage.
CMC: Carboxymethyl cellulose. Synthetic
size used in cotton fabric processing.
Colorant: A
colouring matter, a dye or pigment which can produce colour in a substrate like
fiber, yarn or fabric.
Coloration: A
series of textile operation involved to impart color in textiles. It embraces
dyeing, printing, painting, spraying and preparatory treatment as well.
Color: 1. (Sensation)
that characteristic of the visual sensation which enables the eye to
distinguish differences in its quality, such as may be caused by differences in
spatial distribution or fluctuation with time.
2. (of an object) the particular visual
sensation caused by the light emitted by, transmitted through, or reflected
from the object.
Colour can be described approximately
in terms of Hue, Saturation, and Lightness, or specified numerically by
chromaticity coordinates. Alternatively , colour can be specified by reference
to visual standards e.g. the Munsell Color Atlas.
Colorfastness:
Resistance to fading; i.e the property of a dye to retain its color when the
dyed (or printed) textile material is exposed to conditions or agents such as
light, perspiration, atmospheric gases, or washing that can remove or destroy
the color.
Color strength:
A measure of the ability of a dye to impart color to other materials. Color
strength is evaluated by light absorption in the visible region of the
spectrum.
Colorist: In
textile coloration, a person experienced in developing color formulas,
evaluating samples for color and producing colored samples to meet standards.
Color index (CI): A listing of dyes and chemical structures published by the Society of
Dyers and Colorists. Each structure is assigned a name according to chemical
composition. Each dye is assigned a number according to its class and shade. A
correlating structure number is given when available.
Compatibility:In
textile dyeing, propensity of individual dye components in a combination shade
to exhaust at similar rates resulting in a buildup of shade that is constant,
or nearly constant, in hue throughout the dyeing process.
Copper chelating value (CuCV): The milligrams of copper sulfate pentahydrate chelated by one
gram of a chelating agent or product containing a chelating agent.
Cross dyeing:
A process of dyeing textiles containing fibers having different dye affinities
to achieve a multicolored effect.
Desizing: The
process removal of size materials from greige (gray) fabric to prepare for
dyeing.
Dip: Immersion
of a textile material in some processing liquid. The term is usually used in
connection with a padding or slashing process.
Direct dyes: A class of dyestuffs that are applied
directly to the substrate in a neutral or alkaline bath. They produce full
shades on cotton and linen without mordanting and can also be applied to rayon,
silk and wool. Direct dyes give bright shades but exhibit poor washfastness.
Disperse dyes: A
class of water-insoluble or slightly soluble dyes originally introduced for
dyeing cellulose acetate and usually applied from fine aqueous suspensions.
Disperse dyes are widely used for dyeing most of the manufactured fibers.
Dyes/dyestuff: Substances
that add color to textiles. They are incorporated into the fiber by chemical
reaction, absorption, or dispersion. Dyes may be divided into natural and
synthetic types. Natural dyes are extracted from root bark, flowers and marine
growth. Synthetic dyes are chemically compounded through many processes from
coal tar or other sources of hydrocarbon molecules. On basis of application it
is classified as Acid dye, Azoic dye, Basic dye, Direct dye, Disperse dye,
Mordant dye, Reactive dye, Sulphur dye, Vat dye etc. Fluorescent whitening
agent is also a dye.
Dyeing: A
process of coloring fibers, yarns, fabrics or garments with either natural or synthetic dyes under
specified conditions.
Dyeing auxiliaries: Various substances that can be added to the dyebath to aid dyeing. They
may necessary to transfer the dye from the bath to the fiber or they may
provide improvements in leveling, penetration etc. Also call dyeing assistants.
Dye liquor:
The liquid that contains the dye and the reagents necessary for dyeing.
Ecmc: In color
difference evaluation, a single number defining the total color difference in CMC units of a trial from a standard.
Emulsion: A
suspension of finely divided liquid droplets in a second liquid, i,e., oil in
water or vice versa.
Exhaustion: During
wet processing, the ratio at any time between the amount of dye or substance
taken up by the substrate and the amount originally available.
Fixation: The
process of setting a dye after dyeing of printing, usually by steaming or other
heart treatment.
Fluorescent: A
substance that is added to a textile (uncolored or colored) to increase the
apparent light reflectance in the visible region by the conversion of
ultraviolet radiation into visible light and so to increase the apparent brightness
or whiteness of the textile. Similar words brightener.
Florescent whitening agent (FWA): Colorant that absorbs near ultraviolet (UV) radiation and
re-emits visible (violet-blue) radiation. This causes a yellowish material to
which it has been applied to appear whiter.
Foam:
Dispersion of gas in a liquid or solid. The gas bubbles may be any size. The
term covers a wide range of useful products such as insulating foam, cushions,
etc. It also describes the undesirable froth in polymer melts, dye baths, etc.
Hue: The
attribute of color perception by means of which an object is judged to be red,
orange, yellow, green, blue, violet or a combination of these.
Hydrolysis: A
double decomposition reaction involving the addition of the elements of water
and the formation of an acid and a base, an acid and an alcohol, or an acid and
phenol.
Hydrophilic:
Having strong affinity for or the ability to absorb water.
Hydrophobic:
Lacking affinity for or the ability to absorb water.
Indigo:
Originally a natural blue vat dye extracted from plants, especially the indigofera
tinctoria plant. Most indigo dyes today are synthetic. They are frequently used
on dungarees and denims.
Ingrain dye: A
colorant, which is formed, in situ,
in the substrate by the development and coupling of one more intermediate
compounds. The term was originally used for colorants obtained from oxidation
bases and by azoic techniques, but is now reserved for other types of colorant
formed in situ.
Inhibitor: A
substance that retards or prevents a chemical or physical change. In textiles,
a chemical agent that is added to prevent fading, degradation, or other
undesirable effects.
Isoelectric:
Same charge in a certain condition. When positive and negative charges are
equal. The isoelectric point is pH value at which the molecule carries no
electrical charge or the negative and positive charges are equal.
Isotherm:
Constant temperature line used on graphs of climatic conditions or thermodynamic
relations, such as pressure-volume relations at constant temperature.
Jet dyeing machine: A high-temperature piecedyeing machine that circulates the dye liquor
through a Venturi jet, thus imparting a driving force to move the fabric. The
fabric, in rope form, is sewn together to form a loop.
Kier: A large
metal tank, capable to being heated uniformly, used for wet processing.
Kier boiling:
Process of boiling cellulosic materials in alkaline liquors in a kier at or
above atmospheric pressure.
Laboratory sample: A portion of material taken to represent the lot sample, or the original
material and used in the laboratory as a source of test specimens.
Leuco dye: A
soluble, reduced form of a dye from which the original dye may be regenerated
by oxidation.
Liquor ratio: In
wet processing the ratio of the weight of liquid used to the weight of goods
treated.
Lot: A unit of
production or a group of other units or packages that is taken for sampling or
statistical examination, having one or more common properties and being readily
separable from other similar units.
Metal-complex dye: A dye having a coordinated metal atom in its molecule. Unless the term
metal-complex dye is used in direct association with a particular application
class of dye, e.g. metal-complex disperse dye or metal-complex reactive dye, its
use is inexact and inadvisable.
Migration:
Movement of an added substance (e.g. dye or alkali) from one area to textiles
to another. Commonly used to express the movement of color from the dyed area
to the undyed area of cloth.
Mock Dyeing: A
heat stabilization process for yarns. The yarns are wound onto packages and
subjected to package dyeing conditions (water, pressure, temperature) but
without dye an chemicals in the bath.
Mordant: A
chemical used in some textile fibers to provide affinity for dyes. Or a
substance, usually a metallic compound, applied to a substrate to form with a
dye a complex which is retained by the substrate more firmly than the dye
itself.
Mordant dye: A
dye that is fixed with a suitable mordant.
Optical Brightener: A colorless compounds that, when applied to fabric, absorbs the
ultraviolet radiation in light but emits radiation in the visible spectrum.
OWB: On the
weight of bath.
OWF: On the
weight of fabric/fibre
OWG: On the
weight of goods.
OWV: On the
weight of value.
Pad: A machine
for impregnating fabrics with chemicals. It consists essentially of a trough
followed by two or more pairs of squeeze rolls.
pH: Value
indicating the acidity or alkalinity of a material. It is the negative
logarithm of the effective hydrogen ion concentration. A pH of 7.0 is neutral;
less than 7.0 is acidic; and more than 7.0 is basic.
Pick-up: % or
weight added per unit weight of fabric.
Pigment: An
insoluble, finely divided substance, such as titanium dioxide, used to deluster
or color fibers, yarns or fabrics.
Premetallized acid dye: An acid dye manufactured by reacting an equivalent of a suitable
metal ion with one equivalent of a dye, or with two equivalents of the same or
different dyes, capable of chelating the metal.
Preparation:
In textile manufacturing, those processing operations performed on greige
fabric, colored fabric, textile yarns or fibers to ready them for dyeing, printing
or finishing. For example, typical greige cotton fabric preparation includes
singeing, desizing, scouring, bleaching and (optionally) mercerizing.
Reactive dye:
A dye that, under suitable conditions, is capable of reacting chemically with a
substrate to form a covalent dye-substrate linkage.
Reduction clearing (RC): The removals of unabsorbed disperse dye from the surface of
polyester at the end of the dyeing or printing process by treatment in a sodium
hydroxide/sodium hydrosulfite bath. A surface-active agent may be employed in
the process.
Retarder (Retardants): A chemical that, when added to the dyebath, decreases the
rate of dyeing but does not affect the final exhaustion.
Saponification:
Specifically in relation to manufactured fibers, saponification is the process
of removing part or all of the groups from acetate or triacetate fiber, leaving
regenerated cellulose.
Saturation:
The maximum intensity or purity of a color. If the color is as brilliant as
possible, it is at saturation; if the color is subdued or grayed, it is dull,
weak, and low in intensity.
Scouring: In
textile processing, treatment of textile materials in aqueous or other
solutions to remove nature fats, waxes, proteins and other constituents as well
as dirt, oil and other impurities.
Shade: A
common term loosely used to describe broadly a particular color or depth, e.g.
pale shade, 2% shade, mode shade, fashion shade.
Shading: In
colored textile fabrics, gradual changes in hue, chroma and/or lightness
lengthwise or widthwise. When unintended, shading is considered a defect; may
be international for styling purposes.
Sizing: A
generic term for compounds that are applied to warp yarn to bind the fiber
together and stiffen the yarn to provide abrasion resistance during weaving,
Starch, gelatin, oil, wax and manufactured polymers such as polyvinyl alcohol,
polystyrene, polyacrylic acid, and polyacetates are employed.
Softener: 1. A
product designed to impart a soft mellowness to the fabric. Examples are
glucose, glycerine, tallow, or any one of a number of quaternary ammonium
compounds.
2. A substance that reduces the hardness
of water by removing or sequestering the calcium and magnesium ions.
3. A substance used to reduce
friction during mixing and processing when dry powders are added to polymers.
Solubilized sulfur dye: A thiosulfuric acid derivative of a sulfur dye which during
dyeing is converted to the substantive alkali-soluble thiol form.
Solubilized vat dye: A water-soluble salt of the sulfuric ester of a leuco vat dye. After
application to the fiber the parent vat dye is regenerated by hydrolysis and
oxidation.
Solvent dye: A
dye which is soluble in organic solvents, but not in water, and is widely used
in lacquers, inks, waxes, plastics, soaps, cosmetics, fuels and colored smokes.
Souring: Any
treatment of textile materials in dilute acid. Its purpose is the neutralization
of any alkali that is present.
Substantivity:
The attraction, under the precise conditions of test, between a substrate and a
dye (or other substance) where the latter is selectively extracted from the
application medium by the substrate.
Substrate:
1. In textiles, a fiber, fiber assembly,
yarn, fabric or garment to which another material is applied.
2. Fabric to which coatings or other
fabrics are applied. It can be of woven, knit, nonwovens, or weft-insertion
construction. Generally, substrate properties are dependent both on fiber type
and fabric construction. Usually the fabric is scoured, heat-set and otherwise
finished prior to coating or bonding. Many smooth-surfaced manufactured fiber
fabrics require impregnation with a latex prior to coating to ensure adequate
adhesion.
Sulfur dye: A
dye, containing sulfur both as an integral part of the chromophore and in
attached polysulfide chains, normally applied in the alkali-soluble reduced
(leuco) form from a sodium sulfide solution and subsequently oxidized to the
insoluble form in the fiber.
Uneven dyeing:
A fabric dyeing that shows variations in shade resulting from incorrect
processing or dyeing methods or from use of faulty materials.
Union dyeing:
A process of dyeing textiles containing fibers having different dye affinities
to achieve the appearance of a uniform, homogenous color.
Unlevelness:
In textile dyeing and finishing, non-uniform distribution of a dye or chemical
in or on a substrate.
Vat dyes: A
water-insoluble dye, usually containing keto groups, which is normally, applied
to the fiber from an alkaline aqueous solution of the reduced enol (Leuco) form
which is subsequently oxidized in the fiber to the insoluble form.
Wet pick-up:
In textile processing, the amount of liquid, and material carried by the
liquid, applied to a textile. Wet pick-up is usually determined as a percentage
of either the dry or conditioned weight of the textile prior to
processing.
What is stain resistance finish: It is the finish to prevent water & or oils from
penetrating the fabric using potential aqueous & oily stain to bead up
& roll off.
What is soil release finish: Soil release is the term used to describe clean ability of
fabrics by the laundering process.
What is antimicrobial finished: Antimicrobial finish is one kind of chemical finish which
is improve fabric durability on various substrates, impact on people &
their environment, they interact with good & bad microorganism.
What is textile finishing: Finishing has been defined by textile instate as “Descriptive
of processes, physical or chemical, applied to a substrate to produce a desired
effect”. It is chemical or mechanical treatments performed on fibre, yarn or
fabric to improve appearance, texture, or performance.
What is Calender: A machine in which heavy roller rotates in contact under presser, used
to smooth & flatten fabric to close the intersections between the yarns
& to confer a surface glaze.
What do you mean by DP & Curing: DP means Durable Press OR Permanent press, it is a
finishing treatment designed to impart to a textile material or garments the
retention of specific contours including defined creases & pleats resistant
to normal usage, washing or dry.
Curing is a process following
application of a finish to textile fabrics in which appropriate conditions are
used to effect a chemical reaction.
Foam Finishing:
The application of one or more liquid chemicals finishes in the form of a foam
to a textile material with the advantage of low wet pick-up
Wet pick-up:
The weight of liquor taken up by a given weight of the fabric after
impregnation, spraying, or coating element.
Wicking: The
passage of liquids along or through a textile material or along the interstices
formed by textile element & coating polymer of a coated fabrics.
Wrinkle recovery/resistance: A laboratory test to measure angle (degrees) of recovery
from wrinkling or creasing.
Surfactant: An
agent, soluble or dispersible in a liquid, which decreases the surface tension
of the liquid contraction of “surface active agent”
Dye: A
substances usually organic, soluble or dispersed in its medium of application
& which is design to be absorbed or adsorbed by, made to react with, or
deposited within a substrate in order to impart color with some degree of
permanence.
Colorant: Any
chemical that is colored or can become colored in a particular
environment/under certain condition& can be applied/ used to impart the
property of color to a team.
Pigment: A
substance consisting of small particles that is insoluble in the applied
medium & is used primarily for its
coloring properties.
Dyeing: Dyeing
is the application of color to the whole textile material with some degree of
color fastness. Dyeing is essentially a mass transfer process where the dye
diffuses in solution, adsorbs onto the fibre surface & finally within the
fibre.
Affinity: It
is the difference between the chemical potential of dye in its standard state
in the fibre & the corresponding chemical potential in the dye bath i.e.
tendency of a dye to move from dye bath into a substrate.
Substantivity:
The attraction between a substrate & a dye or other substrate under precise
condition of test whereby the test is selectively extracted from the
application medium of substrate.
Exhaustion:
For a single dye the exhaustion is defined as the mass of the dye taken up by
the material divided by the total initial mass of the dye in the bath but for a
bath of constant volume.
CS= concentration of dye in solution,
Cf=concentration of dye in fibre after dyeing
Exhaustion %=Cf/Cs×100
Fixation:
Fixation is basically how much the dye reacts with the fabric. It depends on how much dye is
fixed onto the fabric after considering all the washes.
Fixation %= [{Co – (C1+CW!
+CW2+……..)}/Co]×100
Co= Concentration of
dye initially
C1= Concentration of
dye after dying
CW1,, CW2 are concentration of the dye in each wash.
Textile printing: Printing is the processes by which dyes & pigments are applied
locally or discontinuous to produce various design.
Styles of printing: Direct style, Discharge style, Resist style, Raised style,
Flock style, Cripm style, Burn out style
Discharge printing: always sharp in outline, bright in appearance & give
perfect & sparking whites due to bleaching effect on the discharge agent.
Resist printing: Generally subdued
& the color are less bright, the outlines of the printing motifs are less
sharp.
Methods of Printing: Block printing, Stencil printing, roller printing, screen
printing, Transfer printing, Digital Inkjet Printing
Pigment printing: In pigment printing insoluble pigments which have no
affinity for the fibres are fixed on the textiles with binding agent in the
pattern required.
Binder: The binder is a film forming substance made up of long chain
macromolecules which when applied to textile together with the pigment; produce
a three dimensionally linked network.
Fabric softener: A softener is a chemical that alters the fabric hand making,
it more pleasing to touch. The more pleasing eel is a combination of a smooth
sensation, characteristics of silk & of material being less stiff.
Surfactants: surfactants lower the surface tension of a liquid, allowing
easier spreading & the interfacial tension between two liquids.
Wetting agent: it is a chemical substance that increases the spreading
& penetrating properties of a liquid by lowering its surface tension that
is the tendency of its molecules to adhere to each other.
Detergent: A detergent is a compound or a mixture of compounds,
intended to assist cleaning & acts mainly on the oily films that trap dirt
particles.
Emulsifying agent: Emulsifying agent are surfactants that convert water
insoluble oils into stable, aqueous suspensions.
Dying Kinetics:
The rate of transfer of dye in solution from the dye into substrate.
Diffusion: Diffusion
means penetration/movement of substance owning the existence of conc. Gradient
i.e. movement of particles between the two surfaces having different density
from higher to lower one.
Mineral
color: Mineral color contains
metallic insoluble precipitates which are deeply colored. These insoluble
precipitates have found great application as pigment for paint. For other
purposes of dyeing, the precipitates themselves are not used but they actually
created in and on the fibers from the soluble substances
What is hard water: Water described as
"hard" is high in dissolved minerals, specifically calcium and
magnesium. Hard water is not a health risk, but a nuisance because of mineral
buildup on fixtures and poor soap and/or detergent performance.
Soap: soap is a metallic salt of saturated or unsaturated higher fatty acid.
There may be pb, Mg, Ca or other metallic salts.
Thickener: Thickener is a thick mass which impart stickiness &
plasticity to the printing paste so that it may be applied on the fabric
surface without bleeding or spreading & be capable of maintaining the
design outline.
Ageing: Ageing consists of exposing printing goods to more or less prolonged
action of steam at atmospheric pressure to assist in the diffusion &
fixation of the dyes
Color: Color is the result of an interaction between a chromospheres group or
color bearing group & light.
Light: That aspect of radiant energy which
human observer is aware through visual sensation arising from stimulation of
the retina by radiant energy.
Metamerism: A pair of sample is said to be metameric if their colors
match under one light source & not match under different light source, this
phenomena is called Metamerism.
Foam: Foam is a dispersion of gas in a liquid. The gas may be generally air,
otherwise inert gas. Foam is different from emulsion.
Emulsion: Emulsion is a mixture of two or more immiscible liquids e.g (water +
oil) with emulsification agent.
Why foam is used?
Ans. In wet processing technology cost is very high mainly due to high
consumption of energy which itself is the result of high consumption of water.
The idea of replacing water in the use of foam reduces the total processing cost by reducing these costs- 1.
Heating cost. 2. Effluent treatment
cost. 3. Chemical & dye stuff
cost
Solvent Dyeing: The use of solvents as dye bath media instead of water
becomes quite a popular concept, where solvent carries the dye molecules to the
interior of fibre & then recovered. Introduction of Hydrophobic fibres like cellulose acetate has pronounced
dyeing problem as no synthetic & natural dye at that time , are capable of
dye it.
Heat setting:
Heat-setting is a heat treatment by which shape retention, crease resistance,
resilience and elasticity are imparted to the fibres. It also brings changes in
strength, stretchability, softness, dyeability and sometimes on the color of the
material. All these changes are connected
with the structural and chemical modifications occurring in the fibre.
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