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Dyes, Printing and Tanning Methods: Azo-Free Colorants

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0% found this document useful (0 votes)
238 views9 pages

Dyes, Printing and Tanning Methods: Azo-Free Colorants

Uploaded by

Trisha Ghosh
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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Fabric and garments are often given certain treatments to achieve a desired color,

effect or performance. The techniques used vary in the amount of water required (which
requires energy to treat before being discharged to the environment), the amount and
toxicity of the chemicals used (which could require significant amounts of energy to
extract, manufacture and process and can pollute environments exposed to them), and
the energy required to carry out these techniques themselves. Sustainable dyeing,
printing and tanning methods focus on reducing the environmental impact in one or
more of those categories.

Finishes used on textiles can be wet or dry; wet describing chemicals applied to a fabric
and dry being those applied mechanically. Dry finishes are generally considered
environmentally preferable and consumer friendly as they use machinery and heat
rather than chemicals. However, there are some eco-friendly wet finishes, which are
increasing in selection and availability, such as enzymatic treatments. Other wet
finishes, such as antimicrobial and stain-resistant, can be beneficial to the sustainability
of a garment, as they reduce the need for laundering, conserving water and energy and
reducing the amount of chemicals released to the environment.

DYES, PRINTING AND TANNING METHODS


Azo-free colorants 
http://www.azofree.org/
Azo-free colorants are dyes and pigments that are free of the nitrogen-based
compounds aromatic amines, also referred to as "Azos". These compounds are toxic
and banned in the EU due to their mutagenic, carcinogenic and often allergic properties.
These dyes are not biodegradable.

Biodegradable
Biodegradable refers to dyes that do not require the use of inorganic salts, heavy metals
and amines. They are substances that decompose readily and become absorbed by the
environment.
Chlorine-free bleaching
Chlorine-free bleaching is the use of hydrogen peroxide to whiten fabrics. Hydrogen
peroxide naturally degrades into oxygen and water, leaving no harmful chemical residue
on the cloth or in the effluent. It is sometimes referred to as Green Bleach.

Chrome-free tanning
Chrome-free tanning is the tanning of hides to create leather either through the use of
oils or natural tannins instead of chromium salts. This tanning process is more time
intensive than chrome tanning, but is better for the environment, as the chromium
method uses chrome, a known carcinogen that can be absorbed through the skin and
cause contamination of soil and waterways surrounding tanneries. 

Cold or low temperature dye processes


Cold or low temperature dye processes save energy by operating at atmospheric
temperatures and do not require steaming of the textile to set or fix dyes.
Dry-heat fixation
Dry-heat fixation is a method of fixing reactive dyes printed through the ink-jet method.
The dyed/printed fabric is passed through hot iron plates in lieu of steam. This method
conserves water and energy by using an alternative to steam fixing as well as the ink-jet
printing method.

Dye bath reuse


Dye bath reuse is the practice of recycling the water used in dye baths for subsequent
baths. The water conserved through the bath's reuse is substantial, as anywhere from
10 -50% of dye from one bath does not fix to the fabric.

Eco bleach
Eco bleach is the use of natural phosphates and silicates in cow dung combined with
sunlight to achieve whitening of natural fabrics. This is the most eco-friendly form of
bleaching.

Fiber reactive dyes


Fiber reactive dyes are dyes used to color cellulosic and protein fibers such as cotton,
rayon and soy. The dyestuff bonds to the fibers through a chemical reaction and does
not require the use of mordants. Therefore, direct dyes require less salts and heavy
metals to be used to achieve optimal coloration and fixation than other commodity
dyestuffs. When used correctly, this can reduce not only the salt and metal content of
the effluent, but also the quantity of water used to remove excess dye and the amount
of dye run off. 

Heavy metal free


Heavy metal free refers to dyes that do not require the use of heavy metals to achieve
the fixation of colors. Toxic heavy metals, such as chrome, copper and zinc, which are
all known carcinogens, are commonly used as fixers in dyes. And, although most heavy
metals can be removed from the effluent through wastewater treatment, this often does
not occur.

Ink-jet printing
Ink-jet printing is a method of applying pigment and dyes to cloth using an ink-jet printer.
It is considered the most eco-friendly and efficient method of printing due to its lower
water usage, water wastage and energy consumption compared with other commercial
printing methods.

Low-impact
Low-impact refers to synthetic dyes that do not use substantial levels of heavy metals or
toxic chemicals as fixers.

Natural dyes
Natural dyes are dyes that are created from bark, bugs, flowers, minerals, rust and
other natural materials. Natural dyes allow small producers to retain their traditional
dyeing methods and promote biodiversity. The disadvantage of these dyes is that their
mordants are often heavy metals.

Non-toxic semi-aniline
Non-toxic semi-aniline dyes are non-toxic transparent dyes used to dye leather. These
dyes are derived from coal tar and fully penetrate the leather while preserving the
appearance of natural grains and markings.

Vegetable dyes
Vegetable dyes are a sub-category of natural dyes referring to those that come from
plant matter only.

Vegetable tanning
Vegetable tanning refers to the use of natural tannins to create usable leather from
hides. Natural tannins are present in bark, wood, leaves and fruits of chestnut, oak and
hemlock trees. This process is time intensive, as it can take up to three weeks for the
tannins to fully penetrate a hide. From an ecological perspective, vegetable tanning is
preferable, however the leather produced is not stable in water as it shrivels and
becomes brittle.

Wastewater recycling
Wastewater recycling is the use of tertiary treated wastewater in the dye baths and/or
for irrigation purposes. This water is suitable for human contact but is not potable. Its
use reduces the strain on potable water supplies particularly in arid climates and is an
effective way to re-use this valuable resource.

FINISHES
Antimicrobial
Antimicrobial is a wet finishing technique that is durable. It is an application of chemicals
that inhibit the growth of odor causing bacteria and fungi. This is of particular use on
wicking synthetic performance fabrics, which tend to accumulate perspiration and
wetness, breeding microorganisms. It is also used to help alleviate asthmatic reactions
by creating a hostile environment for dust mites.

Anti-mites
Anti-mites is a wet, durable finish. Chemicals that inhibit the growth of mites are applied
to the fabric. It is also used to help alleviate asthmatic reactions by creating a hostile
environment for dust mites. (See Antimicrobial.)

Bacteria resistant
Bacteria resistant is a wet finishing technique, which is durable. Chemicals that inhibit
the growth of bacteria are applied to the fabric. 

Biowash
Biowash is a wet, permanent finish that is usually done before dyeing. It is also referred
to as bio-polishing, and is done only to cellulosic fabrics. During this process, enzymes
are applied to the fabric under acidic conditions and at a high temperature to weaken
fibers that would normally pill, and instead of pilling, they readily break-off.

Brushed
Brushed is a variation of napping. (See Napped.)

Calendered
Calendered is a dry finish that creates a very smooth, lustrous fabric. There are many
types of calendering which vary in permanence. All types involve passing the fabric
through large heated rollers that flatten the yarn.

Chintz
Chintz is a calendered finish given to chintz fabric, and is often called glazed chintz. The
glazing gives the fabric a glossy smooth appearance and enhanced hand, drapability
and durability produced by applying to the fabric a finish composition comprising a
silicone polymer and a catalyst.

Crinkle effect
Crinkle effect is either a wet or dry finish depending on the fiber content of the fabric. On
cotton, a crinkle effect can be achieved through the use of sodium hydroxide. On
synthetics a crinkle effect can be achieved through the application of a heat set finishing
technique.

Enzymatic treatments
Enzymatic treatments are wet, permanent finishes in which cellulose enzymes are used
to soften the hand, improve the color by shearing the fabric or to stonewash cellulosic
fabrics. This process is non-toxic and entirely eco-friendly.

Fluorocarbon-free
Fluorocarbon-free are finishes, generally DWR (dirt and water repellent), which are free
from harmful fluorocarbons.

Foam finishing
Foam finishing is an alternate process for applying wet finishes in which the finishing
chemical is applied as foam, using air as a diluter instead of water. This process
reduces energy and water consumption by reducing the need for water and the heating
of it as well as reducing fabric drying times.

Formaldehyde-free
Formaldehyde-free refers to wet finishes that do not use formaldehyde as a fixative,
which is a suspected carcinogen, known allergen and whose use in textiles is now
regulated in many countries.

Heat setting
Heat setting is a dry, durable finish for synthetic fibers that creates a crease resistance
or permanent pleats by setting the fabric either flat or pleated.
Microsanded
Microsanded is a dry, permanent finish. During this process, the fabric is passed
through abrasive rollers to pull fibers to the surface, creating a soft hand. It is a variation
of napping.

Nano-treatments
Nano-treatments are wet finishes of low molecular weight fiber-reactive fluorocarbons
that are added to a fabric to create a self-cleaning mechanism that repels both water
and oil.

Napped
Napped is a dry, permanent finish in which fibers are raised from the fabric by bristled
rotating brushes. This finish allows the fabric to provide more insulation, while also
lowering its resistance to abrasion.

Peach
Peach is a dry, permanent finish in which fabric is passed through emery-coated
cylinders to create luster and an evenly raised nap. This process is also known as
emerized peach finish and is a variation of napping. When applied to nylon, this finish is
sometimes referred to as PD. 

Preshrunk
Preshrunk is a dry, permanent finish in which the fabric is washed in order to create a
more stable fabric. Often this process allows the elasticity to become improved due to
an increase in yarn crimp. After a fabric is preshrunk, there usually remains potential for
additional or residual shrinkage.

Shearing
Shearing is a dry, permanent finish used to create a uniform surface of napped or pile
fabrics.

Soil release
Soil release is a wet, durable finish that increases the absorbency of a fiber that is
hydrophobic in order to allow water to better penetrate the fabric in laundering, thus
allowing dirt and stains to be removed.

Stain resistance
Stain resistance is a wet, usually semi-durable finish applied to a fabric in order to resist
the penetration of a liquid stain substance while allowing the passage of air and
moisture. The finish can be a wax emulsion or other chemical, and each option varies in
efficacy, toxicity and eco-friendliness.

Suede
Suede is also known as carbon suede finishing, and is a variation of napping. (See
Napped.)
Teflon coated
Teflon coated is a process in which Teflon is chemically bonded to a fabric at a
molecular level to create a water repellent and stain resistant finish. It is highly effective
in that it does not change the hand or breathability of the fabric.

Washable wool
Washable wool is a wet, durable finish used to reduce shrinkage in wool. A resin
coating is added to the wool fibers to prevent them from overlocking during laundering.

Water repellent
Water repellent is a wet, usually semi-durable finish applied to yarn rather than a
finished fabric in order to resist the penetration of water while allowing the passage of
air and moisture. The finish can be a wax emulsion or other chemical, and each option
varies in efficacy, toxicity and eco-friendliness.

Water resistance
Water resistance is a finish that resists the absorption of water. (See also Water
repellent.) 

TRADEMARKED FINISHES
3XDRY®
http://www.3xdry.com/

3XDRAY® treatments combine two technologies into one textile: on the outside the
textile is finished with a water-repellent function, whereas on the fabric.s inside it
absorbs perspiration. The treatment does not affect the appearance, hand or the air
permeability features of the fabric.

AEGIS EcoFresh®
http://www.microbeshield.com/

EcoFresh means products stay fresher longer and require fewer launderings. This
reduces the amount of detergents released into the environment and helps conserve
valuable resources such as water and energy. Products using Aegis technology are
protected against odor-causing bacteria, mold, mildew and contaminating fungus. This
technology is durable without the use of heavy metals and does not leach onto you or
into the environment.

AEGIS Microbe Shield®


http://www.microbeshield.com/

The AEGIS Microbe Shield® technology controls the growth of odor-causing bacteria
and fungi, reducing odor, staining and deterioration, which is the most common result of
repeatedly using active wear and equipment. AEGIS Microbe Shield® provides
protection against microbial growth without leaching onto the skin or crossing the skin
barrier. It is also effective against a wide range of microorganisms from bacteria to
fungal contamination like mold, mildew, algae and yeast. AEGIS Microbe Shield® is
compatible with almost all natural and synthetic fibers.

Dryon™
http://www.consoltex.com/pages/brands/dryon.aspx?lang=EN-CA

DryonTM is a water-repellent finish that was initially designed to protect surgeons and
medical personnel against contamination by fluids.

DuPont™ Active Layer


http://www2.dupont.com/Active_Layer/en_US/

DuPont™ Active Layer is a family of recyclable, renewably sourced monolithic film that
works on the principal of moisture absorption on the inside of the fabric, water vapor
diffusion through the fabric, and then evaporation from the outside face of the fabric. In
addition, DuPont™ Active Layer exhibits good stretch and recovery qualities, which
reduces the potential for tearing and enhances garment comfort.

ECO STORM™
http://www.teijin.co.jp/english/news/2007/ebd070124.html

ECO STORM™ is a full polyester waterproof and moisture permeable material.


Laminated with a high durability thin polyester film it has a thin, light and soft texture,
which provides advanced waterproof and water repellent properties, moisture
permeability and wind resistance expected of jackets and rainwear for outdoor and
sporting use. Made entirely from polyester, it can be recycled into new fibers with the
ECO CIRCLE closed-loop recycling system operated by Teijin Fibers after products are
collected.

GreenShield™
http://www.greenshieldfinish.com/

GreenShield™ is a high performance fabric finish that manages environmentally


harmful chemicals, and can be used on almost any fabric. Using the principles of micro-
roughness to reduce the use of harmful fluorochemicals on fabrics, GreenShield™
repels water and stains, can be anti-odor (microbe and bacteria resistant) without
leaching harmful pesticide chemistries, and can provide antistatic properties.

NanoSphere®
http://www.nano-sphere.ch/

NanoSphere® is a textile finish developed in accordance with the bluesign® standard.


Water or substances such as oil or ketchup simply run off the NanoSphere® surface,
any residue can easily be rinsed off with a little water. Textiles with NanoSphere®
require less frequent washing and can be washed at lower temperatures.

Pure by HeiQ
http://www.purebyheiq.com/
Pure by HeiQ is a unique technique of treating textiles with silver. Through this
application, a Pure garment becomes naturally odor free, since silver is a naturally
occurring active element. With HeiQ.s unique technique of blending Pure silver into the
fabric, .smelly bacteria. do not have the chance to colonize the textile, all the while
maintaining the skin.s natural balance of good bacteria.

SmartSilver™
http://www.smartsilver.com/

SmartSilver™ is added to Eclipse™ Base Layer performance fabrics to further enhance


their functional benefits of wicking and breathability. SmartSilver™ provides anti-odor
benefits and material degradation protection and will not wash out or wear off for the
expected life of the garment. It is also approved by the International Oeko-Tex®
Association, which means that it is free from harmful levels of more than 100
substances believed hazardous to human health.

StainSmart®
http://www.milliken2.com/StnSmrt/StnSmrtH.nsf/page/index.htm

StainSmart® is a stain protection technology, allowing liquid spills to bead up and roll
off. StainSmart® is wrinkle resistant and machine washable, color stays in and won.t
wash out.

STORM DENIM™
http://www.cottoninc.com/PressReleases/?articleID=366

STORM DENIM™ technology provides water-repellency, protection from the cold and
damp, and breathability. The STORM DENIM™ finish is applied in garment-form and
compares well to synthetics in terms of water repellency, but beats these products in
breathability. The finish is durable and tested against unfinished denim of the same
weight offers better fill and warp tear resistance, as well as improved warp flex abrasion.

Unidyne TechnaGard®
http://apparelmag.com/ME2/dirmod.asp?
sid=&nm=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&ti
er=3&nid=0C31D3D63D9D4C41A7AE012BF50FC818

Unidyne TechnaGard® is a Daikin, Dow developed series made with fluorine-based


chemistry in a C6 platform, which offers water and oil repellency and stain-release
properties. It is a fabric treatment that delivers the advantages of two complementary
chemistries: the super oil and water repellency of fluorine and the softness of silicone.
Additionally, the series has been approved by the U.S. Environmental Protection
Agency.
Zelcon®
http://www.fountainsetbc.com/supplex_zelcon_spandex_jersey.htm

Zelcon® is a DuPont registered trademark. It is a wet finish that is a combination of both


soil release and wicking. It is used on synthetic fibers, and is soft and stretchy, as well
as windproof and breathable. It also has quick dry and water resistant properties.

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