Source:The Stitch Times


Over the last eight years, Ozone has made a prominent placefor itself in the garment processing industry all over the world. Widely usedas a bleaching agent, Ozone remains a powerful, secret tool within the denim industriesthat gave denim garments an unique and distinctive look and feel from othertraditional processing.


Even today, many manufacturers in India still feel that byusing Ozone Gas their denim garments they would simply bleach them to lighter blueonly. This is true since the Indian denim manufacturers and users are used tothe brighter colour of Indigo achieved with the help of optical brightenersthat sometimes it is difficult for them to accept the duller colours achievedthrough Ozone processing.


Though it changes the colour of the Indigo dye, Ozone eliminatestinting 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 alsodestroys all air borne micro-organisms including bacteria, virus, mold, fungi,spores, etc. It also oxidizes the volatile organic chemicals, includingaromatic chemicals reducing them into lower molecular organics which are no morearomatic in nature; hence the hand-feel in garments is enhanced after thetreatment. Furthermore, the discharge of the Ozone purifies the atmosphere byadding freshness and giving clear, pollution free-oxygen rich air.


Since ozone has the bleaching property, low ozone dosagehelps in avoiding bleaching action, while enabling the washed clothes come outbrighter it also sanitized them at the same time. Ozone's sanitizing propertymakes it very relevant to the hospitals as also the hotels. The use of ozonereduces the requirement of detergents and also the wash can be achieved atlower temperatures. Thus, a specially designed Ozone system helps in reducingthe use of water as well as energy cost for heating, resulting in largesavings. Besides this, the added advantage is that the waste water from the laundryhas much lower detergent contents which requires very little or no waste watertreatment prior to letting it out in to the sewage system.


In the Ozone processing system, first the Ozone is generatedby isolating pure Oxygen from atmospheric air through sophisticated electrodes andpump that air to next equipment fitted with another set of electrodes thatconvert oxygen into ozone and pumps it for garment processing. To maintain thepurity of the ozone generated, the temperature is kept below 14C during theconversion for which chilled water is used. Special chillers are used for thispurpose along with ozone generators.


Tumbler is the third part of this process, where ozone gasis 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 8to 10 min. holding time for the Ozone gas. During this time; tumbling actionslowly turns over the garments for even exposure to the gas circulating in theentire tumbler. Later, with the help of the exhaust pipe the gas in the tumbleris flushed into the atmosphere or to effluent treatment system.


About the Author


S.P. Keshan is Managing Director of Spectrum Washing PrivateLtd., Sonepat, who has been successfully using ozone system from Dr AykanTextiles and Celikhan Makine, Istanbul, Turkey.


About Ozone


Ozone is tri-atomic oxygen, it exists in nature within thestratosphere (from a height of 10 kms to 50 kms), small amounts of ozone isconstantly being produced by the action of sun's UV radiation that splitsoxygen (O2) to from single oxygen atoms. These atoms combine with the remainingoxygen molecules to form Ozone (O3) molecules, which are very effective atabsorbing suns UV rays.


Ozone is also formed from the pollution from burning fossilfuel which creates smoke and carbon monoxide, and lighting creates nitrogenoxides. All of these chemicals, combined together with unstable compounds andin the presence of sunlight, form ozone as a by-product. At ground level, ozoneat atmospheric conditions is very unstable, due to this unstable nature; itreduces to oxygen within a very short span of 60 min. in air and 20 mins. inwater. This reduction reaction releases one atom of oxygen with act as a verypowerful oxidizing agent as a very powerful disinfectant, on the principle ofoxidation the garments are treated and the color, look appears on the treatedgarments.


Originally published in The Stitch Times; May 2009