Imagine 2003). Fiber reactive dye has such

Imagine a world without dye technique. Then we are just as same as
barbarian, people may all dress in same color with less personality and
creation. Dye technique is the incentive of human progress, which provides us a
more colorful world. To be specific, there are several types of dye. First type
of dye is fiber reactive dyes. “The best dyes, by far, to use for cotton and
other cellulose fibers are the fiber reactive dyes.” (Burch 2003). Second dye
is direct dyes, which is an all-purpose dye use on cotton. Third dye is vat
dyeing, which means dyeing in a bucket or vet this is an ancient way of dye.
Fourth dye is naphthol used on cellulosic fibers. Fifth dye is acid dye
usually used on protein fibers. And last is disperse dye which is use on polyester.
Different material responds to different types of dye technique.

Different dye technique occurs verities reaction at the molecular
level. For instance, fiber reactive dyes, which is most popular dye or best dye
on cotton and other cellulose fibers in the dye industry. “they are much
brighter, longer-lasting, and easier-to-use than all-purpose dyes.” (Burch
2003). Fiber reactive dye has such a well-known reputation is due to the
molecule structure. “Unlike other dyes, it actually forms a covalent bond with
the cellulose or protein molecule. Once the bond is formed, what you have is
one molecule, as the dye molecule has become an actual part of the cellulose
fiber molecule” (Burch 2003). A strong bond of the molecule makes color of dye
is the most permanent. Which guaranteed best of quality of dye.  

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For direct dye, this type of dye is not a strong bond. Consequently,
this is a type of inexpensive dye. “Direct dyes are only loosely associated
with the fiber molecule through the property called substantivity” (Burch 2003)
direct dyes are easy to wash off. As burch said,” Without an appropriate
after-treatment, direct dyes bleed a little with every washing, losing their
brightness and endangering other clothes washed in the same load.” The best way
to wash a direct dye product is cool water. Because there is no bond between
dye and fabric.

For vat dye, it is a difficult way of dye. Because individuals
must solubilize it before using it. “The dye is soluble only in its reduced
(oxygen-free) form. The fiber is immersed repeatedly in this oxygen-free
dyebath, then exposed to the air, whereupon the water-soluble reduced form changes
color as oxygen turns it to the water-insoluble form.” (Burch 2003) The color
of vat dye only appears when the product is exposed in to air.

For naphthol dye, it can be applied into two major way, first is
immersion method second is hand painting. “naphthol dyes are insoluble azo
dyestuffs that are produced on the fiber by applying a Naphthol to the fiber
and then combining it with a diazotized base or salt at a low temperature to
produce an insoluble dye molecule within the fiber.”

“(Islam Kiron 2017). Naphthol dye
is a comparatively cheaper way of dye, but it also causes more hazardous than
other way of dye, such as fiber reactive dyes. Furthermore, using naphthol
people need to be extremely caution “Use only with extreme caution, to avoid
the risk of bladder cancer and other deadly diseases.” (Burch 2003)

dye is used for protein fibers. This type of dye is highly water soluble. The
chemical structure of the acid dye is complex. “Acid dyes are really complex in
structure having also large aromatic molecules, sulphonyl group and amino group
to enhance solubility. Acid dyes can be part of the following three main
groups: anthraquinon acid dyes, diazo acid dyes, tiphenylmethane acid dyes.” ( Milano

    Disperse dye is a kind of dye almost
insoluble in water. Due to the smallest molecule structure ” The general
structure of disperse dyes is small, planar and non-ionic, with attached polar
functional groups like -NO2 and -CN.  The
shape makes it easier for the dye to slide between the tightly-packed polymer
chains.”. (Heulwen Price)

Mordant is a chemical component that improve the bond between
fabric and dyes. It either acid or alkaline. On the one hand adding mordant
into dye progress can changed color of fabric make it brigher or darker, “The
type of mordant used can change the color of both the dye-plus-mordant solution
and influence the shade of the final product. Some mordants (FeSO4) darkent the
color, some (SnCl2) brighten the color.” (Shishir 2014) On the other hand it
can improve washfastness of the fabric. The color will stick with the fabric
which last longer. “A mordant is a substance used to set dyes on fabrics by
forming a coordination complex with the dye which then attaches to the fabric.
A mordant is always a polyvalent metal ion. The resulting coordination complex
of dye and ion is colloidal and can be either acidic alkaline.” (Shishir 2014)

Acidity effect on the color of fabric. Different chemical
structure of the acid dye makes different color. There are four main types of
chemical structure: Azo, Anthraquinone, Premetalized and Triphenymethane.
“Anthraquinone type: Many blue dyes have this structure as their basic shape.”
(Dharma 2013).  For Azo structure “Azo dyes
are a separate class of dyes primarily used in on cellulose fibers such as
cotton and rayon, but many acid dyes have a similar structure; most give
different shades of red.” (Dharma 2013) For triphenylmethane dye “There are
many yellow and green dyes commercially applied to fibers that are related to
triphenylmethane.” For Premetallized, “Premetallized acid dyes fall into two
classes, 1:1 metal-complexes, in which one dye molecule is complexed with one
metal atom and the more modern 1:2 metal complexes, in which one metal atom is
complexed with two dye molecules. The dye molecule is typically a monoazo
structure containing additional groups such as hydroxyl, carboxyl or amino
groups, which are capable of forming strong co-ordination complexes with
transition metal ions, typically chromium, or cobalt.” (Dharma 2013). Different
types of acid changed color of fabric, due to their acidity.

conclusion, dyes technique is part of necessity of modern society.
Understanding the concept of dyes, mordant and acidity start from their
molecule level. Helping us identify different reaction of the dyes react on
fabric. So, we can choose the right dyes for fabric under certain request such
as wash fastness, saturation of the color, brightness, and temperature of the
condition. Dye technique makes our world more colorful then before. 

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