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Transcript of DYES
Intro to Dyes
Types of Dyes
Dyeing Vs. Printing
Methods of Dyeing
Fabric Knowledge for Merchandisers
A dye is a
substance that has an
to the layer to which it is being applied
dyes are those dyes which
colours on a substance within a
dyes are the
to apply and the
during their initial cost
Dyes can be used to impregnate layers with colour through
and to display intricate designed patterns, through
TYPES OF DYES
Basic dyes are most commonly synthetic
They are actually aniline dyes
Their color base prevents them from being water soluble, therefore need Mordant
Mordant is an agent that binds the dye to the fiber
They are used with mordant for cotton, linen, acetate, nylon, polyesters and acrylics. Ex. Methylene blue
Substantive Direct Dyes
Mordant (Chrome) Dyes
Oxidation dyes are generally colourless
Aniline black is still one of the most intense and fastest blacks available
Primarily used for dyeing cottons
These can be applied to wool, silk and acetate.
It forms the basis of the hair dyes
Acidification of basic dyes led to the creation of acid dyes
Acid Dyes are used for dyeing protein fibers.
Acid dyes are used on wool, angora, cashmere and silk.
Also used for acetate, nylons, acrylics and spandex
These dyes have one molecule of metal, usually chromium, bound to two molecules of dyes.
The shades are not so bright as acid colors.
These dyes are suitable not only for piece dyeing but also stock and package work
These dyes are used for wool, silk, nylon, acrylics, and modacrylics
Mordant dyes can be defined as those dyes that requires a mordant for application as a dye
Colour Index classification of mordant dyes would be like this- mordant + base colour + number. Ex. Hematein (natural black 1)
These dyes require addition of chrome derived from potassium or sodium bichromate
These dyes are primarily used for wool
Prevents color bleeding.
A class of coloured, water-soluble compounds that have an affinity for cellulose fibres Ex. Cotton and Rayon
Direct dyes are usually cheap and easily applied, and they can yield bright colours but duller than basic or acid dyes.
Much used for printing on dischargeable dyed backgrounds
Direct dyes that are further identified as Naphthol and Rapidogen
AZO Dyeing Process is such a process in which the insoluble azoic dye is produced on the or within the fiber
Mainly in three colors and these are red, brown and yellow.
These dyes are primarily used for cotton goods
Originally developed for the dyeing of cellulose acetate
These dyes are finely grounded in the presence of a dispersing agents and then sold as a paste, or spray-dried and sold as powder
These can also be used for dyeing nylon, cellulose triacetate, polyester and acrylic fibers
Used for dyeing and printing both.
Mainly used for dyeing cellulose fibers
Can be also used for dyeing staple fibers and yarn.
It is done at high temp and with a large quantity of salt, which helps to drive the color into the fabric
Colors are not bright.
Used for heavy woven and knitted cotton goods as well as linen and jute
Also used for printing
The name VAT DYEING has been derived from the fact that the dyeing process is performed in a VAT or bucket.
Vat Dyes are based on original Indigo dye that is a kind of natural Dye
These dyes can be dissolved into water only when these are oxidized.
Primarily used for cotton and wool.
Much used for printing. Ex. Indigoids
Reactive dyes or fiber reactive dyes are basically a class of highly coloured organic substances
Quite capable of a direct reaction with fiber substrate
Among the most permanent of dyes due to the formation of covalent bonds with the fabric.
Applicable to stock, yarn, piece goods and printing.
They can be applied at room temperature
They are not true dyes because they have no affinity for the fiber and are applied and held to the fabric with resins which are then cured at high temp.
Primarily for printing cotton of all weights; also wool rayon acetate, nylons, polyesters
They got complete shade range in bright colors
Dying Vs. Printing
Substantive Direct Dyes
Neutral Pre-Metalized Dyes
Mordant Chrome Dyes
Oxidation Bases Dyes
Basic Cationic Dyes
When two or more types of fabrics are dyed, particularly by different dyers, the colors may appear to match in one light, but will not match in another light. Such a condition is known as Metamerism or color flare
Metamerism is the matching of apparent color of objects with different spectral power distributions. Colors that match this way are called metamers
TYPES OF DYEING
First and widely used method is that of removing the packed fiber from the bales and then packing the stock in large vats and circulating dye liquor through the mass fiber at elevated temperature.
The another (new) method, bale dyeing, which is applicable to wool and all types of manmade fibers, is that of splitting the bale covering on all six sides, placing the entire bale in a specially designed, and then forcing the dye liquor through the bale of fiber.
It is the most expensive and effective dyeing method.
Woolens are often stocked dyed.
Top is wool that has been combed to take out the short fibers.
One step nearer to the finished yarn than stock dyeing is what is called top dyeing.
The top is wound on perforated spools and the dye color is circulated through it.
Very even dyeing is possible with this method
SKEIN (HANK) DYEING
There are several methods of yarn dyeing.
Cloth made up of dyed yarn are called yarn dyed.
Yarn dyed fabrics are usually deeper and richer in color.
The primary reason for dyeing in the yarn form is to create interesting checks,
Stripes and plaids with different colored yarns in the weaving process.
Skein (Hank ) Dyeing
Examples of Yarn Dyeing are:
Yarn may be prepared in skein, or hank form and then dyed.
The loose arrangement of the yarn allows for excellent dye penetration.
The skeins are hung over a rung and immersed in a dye bath in a large container.
This is the most costly method but the color penetration is best and the yarns retain a softer, loftier hand.
Yarn wound on spools, cones, or similar units and then dyed is referred to as package dyed yarn.
These packages of yarn are stacked on perforated rods in a rack and then immersed in a tank wherein the dye is forced outward from the rods under pressure through the spools and then back through the packages toward the center to penetrate the entire yarn
This method is similar to package dyeing but it is more economical.
Yarn is wound onto a perforated warp beam, immersed in a tank, and dyed under pressure.
It is used when fabrics are to be woven with dyed warp yarns.
Yarn that is spaced-dyed is dyed at intervals along its length.
One procedure is the knit-deknit method in which the yarn is knitted on either a circular or flat bed knitting machine set to produce desired size of loop. The knitted cloth is then dyed and it is subsequently dek-knitted.
Since the dye does not readily penetrate the areas of the yarn where it crosses itself, alternated dyed and undyed spaces appear
The great bulk of dyed fabric on the market is dyed in piece.
Fabric may be piece dyed whether it is composed of only one kind of fiber or yarn or of blends of different fibers or combination of different yarns.
Simple for one kind of yarn fabrics
Complex for fabrics made up of different types of yarns
Its horizontal shaded band across the width of the fabric.
It may be caused by variation in the size of the
and by the differences in tension of either the filling or warp yarns.
It’s a loss of color when the dyed fabric is wetted or emersed in water.
The water here, becomes colored and may cause discoloration to other fabrics.
This is usually due to either improper dye selection or poor dye fastness.
It is the rubbing off of the color.
Mainly due to friction.
It may rub onto another fabric.
This may be due to inadequate washing subsequent to dyeing.
It refers to a color that does not exactly match
the standard or prepared sample.
This may be faulty dye formation or application
It is a horizontal band of a different hue running across the fabric.
It may be caused by a change of
in the loom or a loom stop and start up
It is a variation in color tone either horizontally or vertically.
It is generally due to uneven tension on the fabric
It indicates a discoloration caused by a foreign substance, dirt, grease, oil or sizing residue on the fabric being dyed
This type of defect on the fabric indicates either a stain or uneven dyeing caused by folds in the fabric during the dyed process.