The Stitch Times
Over the last eight years, Ozone has made a prominent place
for itself in the garment processing industry all over the world. Widely used
as a bleaching agent, Ozone remains a powerful, secret tool within the denim industries
that gave denim garments an unique and distinctive look and feel from other
Even today, many manufacturers in India still feel that by
using Ozone Gas their denim garments they would simply bleach them to lighter blue
only. This is true since the Indian denim manufacturers and users are used to
the brighter colour of Indigo achieved with the help of optical brighteners
that sometimes it is difficult for them to accept the duller colours achieved
through Ozone processing.
Though it changes the colour of the Indigo dye, Ozone eliminates
tinting from the reverse of the denims as also from the sewing thread, pocket fabric,
labels, zippers, buttons etc. giving the garment a cleaner look. Ozone also
destroys all air borne micro-organisms including bacteria, virus, mold, fungi,
spores, etc. It also oxidizes the volatile organic chemicals, including
aromatic chemicals reducing them into lower molecular organics which are no more
aromatic in nature; hence the hand-feel in garments is enhanced after the
treatment. Furthermore, the discharge of the Ozone purifies the atmosphere by
adding freshness and giving clear, pollution free-oxygen rich air.
Since ozone has the bleaching property, low ozone dosage
helps in avoiding bleaching action, while enabling the washed clothes come out
brighter it also sanitized them at the same time. Ozone's sanitizing property
makes it very relevant to the hospitals as also the hotels. The use of ozone
reduces the requirement of detergents and also the wash can be achieved at
lower temperatures. Thus, a specially designed Ozone system helps in reducing
the use of water as well as energy cost for heating, resulting in large
savings. Besides this, the added advantage is that the waste water from the laundry
has much lower detergent contents which requires very little or no waste water
treatment prior to letting it out in to the sewage system.
In the Ozone processing system, first the Ozone is generated
by isolating pure Oxygen from atmospheric air through sophisticated electrodes and
pump that air to next equipment fitted with another set of electrodes that
convert oxygen into ozone and pumps it for garment processing. To maintain the
purity of the ozone generated, the temperature is kept below 14C during the
conversion for which chilled water is used. Special chillers are used for this
purpose along with ozone generators.
Tumbler is the third part of this process, where ozone gas
is introduced and removed after processing. The process time is 15 to 20 min.
per batch, as the volume of the tumbler requires 10 to 12 min. to refill and 8
to 10 min. holding time for the Ozone gas. During this time; tumbling action
slowly turns over the garments for even exposure to the gas circulating in the
entire tumbler. Later, with the help of the exhaust pipe the gas in the tumbler
is flushed into the atmosphere or to effluent treatment system.
About the Author
S.P. Keshan is Managing Director of Spectrum Washing Private
Ltd., Sonepat, who has been successfully using ozone system from Dr Aykan
Textiles and Celikhan Makine, Istanbul, Turkey.
Ozone is tri-atomic oxygen, it exists in nature within the
stratosphere (from a height of 10 kms to 50 kms), small amounts of ozone is
constantly being produced by the action of sun's UV radiation that splits
oxygen (O2) to from single oxygen atoms. These atoms combine with the remaining
oxygen molecules to form Ozone (O3) molecules, which are very effective at
absorbing suns UV rays.
Ozone is also formed from the pollution from burning fossil
fuel which creates smoke and carbon monoxide, and lighting creates nitrogen
oxides. All of these chemicals, combined together with unstable compounds and
in the presence of sunlight, form ozone as a by-product. At ground level, ozone
at atmospheric conditions is very unstable, due to this unstable nature; it
reduces to oxygen within a very short span of 60 min. in air and 20 mins. in
water. This reduction reaction releases one atom of oxygen with act as a very
powerful oxidizing agent as a very powerful disinfectant, on the principle of
oxidation the garments are treated and the color, look appears on the treated
Originally published in The Stitch Times; May 2009