| INTRODUCTION
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| | in this field.
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| Textile industry is a mother industry
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| | A lot of dynamism is thus going to be
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| upon which millions of people are
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| | apparent in the coming years with efforts
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| dependent. Out of the various sectors of
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| | to improve market shares.Mercerisation
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| textile's production, the processing
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| | improves lustre, enhances dyeability, and
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| segment is one of the weak sectors
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| | improves the strength and also the soft
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| although weaving and garmenting also fall
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| | feel. For the cotton fabrics 50 to 54oTw
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| in the same category. Share of Indian
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| | (22.5%) sodium hydroxide solution is used
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| textiles and clothing production is 3.3%
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| | at room temperature for 45 to 60 seconds
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| of the world production and the world
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| | in which case caustic pick up varies from
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| textile export has been growing at the
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| | 25 to 40%. Normally 10% of the caustic is
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| rate of 5.58% per annum and clothing
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| | consumed in the operation on the weight of
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| export 6.44% per annum. The overall
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| | the fabric and 75% of the caustic is
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| textile and clothing export growth rate is
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| | recovered. For the viscose rayon 8 - 10%
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| around 6% per annum. We can say, the
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| | caustic soda is to be used the parameters
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| finished products are being more welcomed
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| | of mercerisation followed by scouring and
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| than the unfinished textiles.From the
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| | washing should be so adjusted that the
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| business strategy point of view too, the
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| | final fabric should be almost neutral. Wet
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| maximum value addition is possible when we
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| | on Wet mercerisation and hot mercerisation
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| go for supplying finished material as RMG
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| | are the additional two processes. In the
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| fabric or the Garments. Due to the
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| | latter 60oC temperature is used causing
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| increase in the demand for clothing, the
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| | the even effect on the skin and core of
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| processed goods are now in large
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| | the fabric and the better dyeability can
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| demand.CHANGE IN TRENDS
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| | thus be obtained. Hot mercerisation can
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| There are lots of factors which are
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| | make use of shorter machine. The
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| responsible for the present day change in
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| | efficiency of such mercerisation operation
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| scenario of the wet processing of
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| | can reflect in barium activity number or
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| textiles. Good quality at competitive
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| | deconvolution count, the former method is
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| prices is becoming the key factor with
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| | however preferred to latter.DYEINGThe
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| trade globalisation. Hence, the wet
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| | proper selection of dyes and machines as
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| processing sequence is accordingly being
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| | well as the dyeing aids are the key
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| changed, keeping in mind the end objective
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| | factors to get right first time products.
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| of obtaining high quality goods at the
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| | The shade matching, the production of
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| most competitive prices.To get the best
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| | solid shades and defect free dyeing are
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| quality fabric of international standards,
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| | the day to day challenges faced by the
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| one needs to have the best of spinning and
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| | dyers.Once the fabric undergoes controlled
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| weaving technologies employed, before
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| | pretreatments and brought in a ready to
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| subjecting the fabric to various
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| | dye stage, the dyeing becomes the next
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| operations of wet processing. However, for
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| | challenge to get uniform and consistent
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| a textile wet processor, it becomes the
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| | shades right at the first attempt (RFT).
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| most challenging task to get the right
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| | The proper selection of dyes and machine
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| shades at first time and also at
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| | depends upon number of factors. The first
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| competitive cost with the best quality.
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| | and the topmost is the nature of the
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| The high performance standards expected by
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| | fibre, the variety and the quantity of
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| the consumer are to be met with, in
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| | fabric being processed as well as quality
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| addition to the adherence to the norms of
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| | standards required. Number of challenges
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| eco-friendly processing, which is the need
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| | faced by the dyer includes shade matching,
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| today. All these characteristics lead the
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| | production of solid shade and defect free
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| direction of research in textile wet
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| | dyeing. With the general knowledge of the
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| processing and the various operations
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| | nature of the dyestuff and performance
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| actually carried out in the processing
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| | properties as well as their applicability
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| industry. Many a times, it has been
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| | on various fibres, the selection of a
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| observed that there is a huge difference
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| | given class of dye is not a big problem.
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| in the process sequence to be ideally
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| | However, depending upon structure of
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| followed vis-a-vis the one actually
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| | individual dyes, its chormophores and
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| practiced at the shopfloor. Otherwise,
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| | auxochromes, hues and substantivity
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| e.g., how do you explain high twisting of
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| | differ. e.g. as a class, reactive dyes
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| microdenier yarn and weight reducing the
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| | react with the cellulosic fibres and thus
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| fabric made out of it with causticisation
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| | said to be giving vary good performance
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| process? There are many other examples.Wet
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| | properties. But they suffer many a times
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| processing can be broadly divided into
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| | with poor extent of fixation, problem of
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| pretreatment, dyeing, printing and
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| | hydrolysis, sensitivity to metal ions,
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| finishing. Irrespective of the various
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| | poor chlorine bleach fastness etc.The use
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| stages of operations falling under the
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| | of salt in reactive dyeing further adds
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| above mentioned classification, every
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| | TDS to the effluents. The advancement in
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| single method followed finds its basis and
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| | this class of dyes are thus aimed at
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| objective of the following:. Maintenance
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| | improving their exhaustion and fixation by
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| of high quality
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| | improving the reactivity and decreasing
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| . Cost effectiveness
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| | their sensitivity to temperature and pH
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| . Better performance
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| | variations. HE and ME dyes showing high
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| . Lower effluents and minimum input cost
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| | exhaustion are thus recommended for dyeing
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| . Minimum use of chemicals
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| | of Knit goods, which is carried out on
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| . Environment friendly process
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| | winches where a lot of variation in
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| . Application of latest machinery which
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| | temperature and pH occur. While the former
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| can guarantee the reproducibility of the
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| | is homo bi-reactive system, the latter one
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| product once
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| | is hetero bi-reactive system and their
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| approved.PRETREATMENTDegumming
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| | fixation claimed to be as high as 85%. The
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| DesizingAlthough, acid desizing, rot
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| | reactive dyes of LS type which make use of
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| steeping and enzymatic desizing are quite
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| | low salt and some based on fluorine are
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| well accepted methods of desizing the
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| | increasingly recommended. While dyeing the
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| fabric containing starch based sizes,
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| | compound shades, the rate of dyeing as
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| different types of amylase base enzymes
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| | well as compatibility of dyes have to be
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| are available in the market and as its
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| | taken into consideration so that the
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| consumption as well as production is
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| | shades do not go off the tone.The vat dyes
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| increasing day by day, the cost of enzymes
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| | are the costliest class of dyes, although
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| is coming down and the processors thus
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| | they offer best of performance properties
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| been able to make use of such enzymes,
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| | and many a times in polyester/cotton
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| which are quite specific in action with
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| | blends, disperse- reactive and
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| respect to concentration, pH, temperature
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| | disperse-vat are recommended. In such
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| and do not pose any danger of fiber
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| | blends selection of disperse dyes is also
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| degradation.In pretreatment, either the
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| | equally important which are stable to
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| yarn or the fabric requires to be treated
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| | alkali so that, once the polyester
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| with such chemicals that subsequently are
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| | component is dyed, the vat pigment
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| turned to be receptive to the dyes and
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| | mechanically deposited is reduced in
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| chemicals as well as finishes. In case of
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| | alkaline blank vat solution. While the vat
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| silk, most of the quality goods
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| | dye thus gets fixed on the cotton
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| manufacturers degum the silk in the hank
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| | component the additional reduction
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| form before subjecting it for bleaching
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| | clearing treatment is totally eliminated
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| and then dyeing. Since, they intend to use
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| | in this case. The recent trend is also to
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| these yarns for woven designs; the
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| | cationise cotton or the cellulosic
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| treatment in the hank form as well as its
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| | material and apply the reactive dyes in
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| colouration becomes handy. Besides the
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| | acidic conditions so that the protonated
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| age-old method of degumming of silk using
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| | or cationised cotton adsorbs the reactive
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| Marsellies soap or sometimes 501 soap,
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| | dye anions at the enhanced rate and
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| nowadays enzyme like Degummase is used to
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| | subsequent fixation in alkaline medium
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| remove the sericin, the cementing agent of
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| | gives very high shade build up. Number of
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| the silk fibroin. Many also prefer to
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| | quaternary amines and cationising agents
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| remove the sericin to a limited extent, so
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| | are used towards this purpose and in many
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| that the strength of silk yarn is kept
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| | cases reactive dye systems can eliminate
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| intact. Companies
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| | the use of salt. This not only reduces,
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| like Himatsingka exporting almost 100 per
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| | the TDS of the effluent, but also
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| cent of their products - upholstery and
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| | drastically reduces unfixed dye being
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| curtain materials, have found an enviable
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| | drained out in the effluent. Polyester
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| position in this business. The Central
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| | fibre dominating the apparel scene, it is
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| Silk Board as well as the ministry of
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| | but natural that one chooses Disperse
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| textiles are working on improving the
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| | dyes. While they are being selected, one
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| quality of silk and training silk reelers
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| | needs to take into consideration their
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| so that India can not only increase the
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| | energy class, diffusion number, migration
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| silk yield but also improve its share in
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| | rating etc. The dyeing is based on
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| the silk trade.Enzymes such as proteases
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| | diffusion-controlled mechanism and thus
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| are also used in wool processing. Not only
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| | for the compound shades, it is highly
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| are the scales removed, imparting
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| | necessary that these dyes are selected
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| anti-felting property, but the wool fibre
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| | from the same subclass so that in general
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| is found to give improved dye uptake.
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| | the performance properties and shade build
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| Cotton fabric is normally subjected to
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| | up are not drastically affected. Serilene
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| desizing and a number of research methods
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| | brand of VX dyes of Yorkshire chemicals,
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| talk about desizing with hydrolytic and
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| | UK offers most compatible range of
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| oxidative desizing agents, plasma
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| | disperse dyes in which case shade
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| treatment, etc. The rot steeping, acid
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| | prediction and matching become relatively
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| desizing and enzymatic desizing are the
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| | easy and their edge in performance can be
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| conventional hydrolytic desizing
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| | apparent from pale to dark shades. Now a
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| techniques which are widely followed.
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| | days, trend is to shorten dyeing cycles
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| However, the recent trend is to use the
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| | and many a times one bath dyeing of the
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| size paste based on acrylic and PVA
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| | binary and ternary blends is attempted.
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| formulations which are easily washable and
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| | Disperse dyes applicable in alkaline
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| the quantity of starch in the size paste
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| | conditions are also offered by some of the
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| is greatly reduced so that BOD in the
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| | manufacturers which are most suitable in
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| effluent is accordingly
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| | polyester cotton blends where the cotton
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| diminished.Different types of enzymes
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| | component requires alkalinity for
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| mainly "amylase based" are in the market,
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| | application of reactive, vat or sulphur
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| which being concentration specific, pH
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| | dyes. One of the methods developed makes
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| specific and temperature specific, are
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| | use of simultaneous disperse-acid dyeing
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| most satisfactorily used. Some of the
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| | and finishing of polyester/cotton bland
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| enzymes require sodium and potassium
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| | .Initially the method was developed for
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| chloride to increase their activities,
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| | one bath acid dyeing -resin finishing of
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| whereas the heavy metal ions such as
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| | cotton/cellulosic material.The selection
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| mercury, copper, zinc, iron are strong
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| | of acid dye however is quite critical and
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| inhibitors for the action of enzymes of
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| | it should have abstractable-H in its amino
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| amylase type. Although the enzymes -
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| | group substituent .Finishing agent like
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| pancreatic, bacterial and malt type work
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| | DMDHEU gets attracted to cotton to one end
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| in the range of 6-7, 5-7 and 4.6 - 5.2 pH
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| | while anchoring or holding acid dye
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| range and the temperature 40-55ø, 60-70ø
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| | molecules on the other end. Dyeing was
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| and 40-50øC respectively, special
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| | quite fast and so called non substantive
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| desizing agent such as Finogene DH 250 N,
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| | acid dyes can be applied on cotton
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| (Korean company) works in the range of pH
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| | simultaneously resulting in improvement in
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| 5-9 and the advantage of such enzyme is
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| | crease recovery angles. When the same
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| that the cotton waxes get partially
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| | system is extended to polyester/cotton
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| emulsified due to the alkalinity, which
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| | blend for disperse-acid-dyeing-cum resin
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| can be removed in subsequent operations.
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| | finishing from single bath by pad -
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| Thermozyme, an enzyme stable at high
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| | thermosol technique, it was found that
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| temperature is known to bring about
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| | polyester and cotton component can be dyed
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| desizing almost instantly at higher
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| | with respective dyes, and heat-setting as
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| temperature.Oxidising type of desizing
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| | well as finishing take place almost
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| agents are energy saving, acting on all
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| | simultaneously. Washing- off problem in
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| the sizes and offer shortening of the
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| | reactive dyes is always a challenging task
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| process sequence. Sodium bromite and
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| | which impairs the fastness properties of
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| potassium persulphate are quite important
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| | the dyes if hydrolysed dye is not fully
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| oxidative agents.ScouringAlthough soda
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| | washed out. Though non-ionic detergent is
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| boil is so far the best method of
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| | recommended for the same, the recently
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| scouring, the efforts are on to make use
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| | introduced Bio rinsing making use of
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| of pectinase and lipase together as one
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| | Bylase RP / Assist RP, the enzyme which
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| shot chemical in which case, it is
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| | decolorises selectively the hydrolysed
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| understood that while pectinase will
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| | dyestuff from the fabric and also the
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| loosen the hydrophobic waxes due to the
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| | unfixed reactive dyestuff in unexhausted
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| hydrolysis of pectins and the lipase can
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| | bath provides a great promise. This
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| bring about the hydrolysis of waxes.The
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| | reduces the consumption of water, energy
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| persulphate could be incorporated in the
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| | and time as it is claimed to be quite
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| scouring process, eliminating separate
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| | efficient washing- off process. The use of
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| desizing stages. Simultaneous desizing and
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| | cationic dye-fixing agent is quite common
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| scouring can be carried out by padding the
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| | in the case of direct dyed material which
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| cloth in 2-3 gpl potassium persulphate and
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| | is obvious as they have very high
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| 40-50 gpl NaOH and subsequently steaming
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| | solubility in water imparting poor wash
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| in J box. While desizing can be achieved
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| | fastness properties. However, due to the
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| in 1-3 mins, scouring takes 90 to 120
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| | presence of unfixed hydrolysed dye on the
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| mins, in J box or 2-10 minutes in vapour
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| | fabric as a result of incomplete
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| locks machines. Of all these methods, acid
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| | washing-off, it becomes essential even in
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| steeping, enzyme and bromite desizing and
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| | case of the reactive dyed material, to
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| simultaneous scouring and desizing with
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| | subject it for the treatment of cationic
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| persulphate are the cheapest as far as
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| | dye fixing agent. The hydrolysed dye
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| cost considerations are concerned. As far
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| | acting as a direct dye being held on the
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| as scouring operation is concerned,
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| | fabric by hydrogen bonding, complexes with
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| although a number of attempts have been
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| | cationic dye fixing agent and brings about
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| made at scouring the fabric using Lipase
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| | fixation of dye, improving its wet rubbing
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| type of enzymes to hydrolyse the
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| | fastness at least by half a grade.In case
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| triglycerides which are hydrophobic in
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| | of garment dyeing, in case of the post
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| nature, there has been no substitute
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| | finishing process, reactive dyes can be
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| really worth mentioning to the soda boil,
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| | used provided the garments so finished are
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| which can give expected absorbency.The
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| | already subjected during finishing with
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| pectinase enzyme is used to hydrolyse the
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| | certain nitrogen containing additives.
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| pectins and remove the same from cotton
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| | These additives used during finishing
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| causing loosening of the hydrophobic waxes
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| | render the dyeability to the finished
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| which are easier to get rid of in
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| | garment and upto about 85% dyeability can
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| subsequent washing. The action of lipase
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| | be regained even after finishing the
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| subsequently brings about hydrolysis of
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| | garment at the intermediate level, which
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| such hydrophobic waxes and thus nowadays,
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| | otherwise is known for displaying only
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| the pectinase and lipase are getting
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| | 15-20% dyeability. This phenomenon of
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| increasing importance in the process of
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| | additives improving the finished goods
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| scouring. One research study indicates the
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| | dyeability works similar to process of
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| pretreatment of the fabric with chloroform
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| | Cationisation and requires almost similar
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| followed by pectinase treatment. But one
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| | conditions as used in dyeing of cationised
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| can understand the limitation of
| |
| | cotton.From the environment point of view
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| application as chloroform is used here to
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| | the general trend is to make use of
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| dissolve non-cellulosic impurities.Solvent
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| | non-dusting powders of the dye and thus
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| assisted scouring makes use of five per
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| | granules are preferred to dusting powders.
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| cent solvent, which is emulsified and also
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| | Higher concentrates of dyes are also used
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| can be coupled with bleaching and
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| | to decrease the volume being handled. As
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| desizing. In this case the hydrogen
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| | the automation is increasingly accepted
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| peroxide not only acts as bleaching agent
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| | and high quality standards become pivotal
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| but also as an oxidative desizing agent.
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| | part of the business, the most modern
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| In other words, alkaline scouring till
| |
| | machines with auto dispensing systems are
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| today remains the most suitable way of
| |
| | coming in use .To cater to such modern
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| scouring. Solvent scouring is of
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| | machine with colour kitchen and auto
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| theoretical importance so far as cotton is
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| | dispensing systems, liquid dyes become an
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| concerned. However, in case of silk and
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| | important and essential formulation.
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| wool, solvent such as perchloroethylene is
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| | Presently the Dispersol and Procion T dyes
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| used, provided sophisticated machinery is
| |
| | are supplied in liquid formulation and so
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| available for total recycling of the
| |
| | also some of the soluble sulphur dyes.
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| solvent. The carbonisation of wool after
| |
| | However, very soon most of the dyestuffs
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| solvent treatment is done with H2SO4.Kier
| |
| | would be required to be supplied in liquid
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| and J boxes are used for scouring of
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| | formulation, so that most modern automatic
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| cotton fabric with soda boil at 4-5 per
| |
| | and microprocessor based systems of dyeing
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| cent on the weight of the fabric with
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| | can be made use of, especially in which
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| wetting agent upto 3 gpl. Sodium sulphite
| |
| | case the shade reproducibility is of
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| (about 1%) brings down the scouring time
| |
| | utmost importance. The Procion T dyes are
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| in the pressure boil which otherwise
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| | acid fixable liquid reactive dyes based on
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| requires 8-12 hours at 30 PSI (1.5-2 Kgs
| |
| | phosphoric acid condensation products and
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| Cm2). Open width scouring though initially
| |
| | they also carry the potential of making
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| was carried out on the jiggers, now pad
| |
| | the fabric flame retardant while being the
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| roll process can also be used. The
| |
| | integral part of the fabric.To continoue
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| recently introduced continuous bleaching
| |
| | to read more articles on Textile, Fashion,
|
| range of Benninger is becoming popular
| |
| | Apparel, Technology, Retail and General
|
| although capital investment is high. The
| |
| | please visit If you wish to download
|
| small processing units can make use of
| |
| | republish the above article to your
|
| modern jiggers for scouring, bleaching and
| |
| | website or newsletters then please include
|
| dyeing in which the goods weighing upto
| |
| | the "Article Source". Also, you have to
|
| about 1,400 kg (3,000 mts bottom weight)
| |
| | make it hyperlinked to our site.Copyright
|
| can be processed.Key pointsIncreasing
| |
| | © 2006Fibre2fashion has emerged as a
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| environment consciousness leading to
| |
| | distinctive B2B platform for global
|
| eco-friendly textile processing has driven
| |
| | Textile, Apparel, Fashion and Retail and
|
| our R&D efforts in search of safe
| |
| | allied industries. offers business
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| substitutes for the dyes and finishes.
| |
| | solutions, news, articles and information
|
| The specific needs of the customers such
| |
| | that help to survive and sustain in the
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| as flame-retardancy or anti-bacterial
| |
| | most hostile and competitive business
|
| properties have further created challenges
| |
| | environment.
|
