GARMENTS WET PROCESSES

Lecture #: 16

INTRODUCTION TO GARMENTS MANUFACTURING GM-2041

Faculty of Engineering & Technology

National Textile University Faisalabad.

NAUMAN ALI

Wet Processing Department

• It’s the department in which garment is under some physical wet processes. Where garment image or out look is enhanced after applying following techniques.

Desizing Enzyme application Bleaching KMnO4 application Tinting/Dye Neutralization Single/Double Stone Wash Garment Wash Fixer & Softeners

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Desizing Desizing removes the solution added to the fabric during the

sizing process. Through the use of desizing agents, the size is either degraded or solubilized. Enzymatic desizing, the most popular method of desizing, uses amylase enzymes to eat away at the sizing; however, the process can also be accomplished with an oxidizing agent or sulfuric/hydrochloric acid.

Enzyme application ECOSTONE® cellulase enzymes contain both neutral, acid and

hybrid enzymes in different concentrations, offering unique combinations that make these enzymes highly effective in creating a rich variety of effects on denim. They give denim finishers the flexibility to use a wide range of washing parameters, depending on the precise requirements of the process.

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Wet Processes

Wet Processes

Enzyme application – Enzyme wash is most common in denim wearing. Typical in denim,

due to its unique fabric construction gets antique look with time passing. An old jean is famous for the white and blue texture that appears on warp and weft of garment. In fashion it is required on fresh articles and enzyme wash is designed to create this effect on garments.

• Bleach Wash: • Bleach wash or light stone wash refers to light blue shades of

denim. The additional step is bleaching to stone wash. This bleaching is usually carried out by strong oxidizing agents. In industry, most widely used chemicals are sodium hypo-chlorite, calcium hypo-chlorite, hydrogen per oxide and potassium permanganate.

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KMnO4 Spray

1. KMnO4 Spray

• Potassium permanganate spray is done on jeans to take a bright effect on sand blast area. One important thing about potassium permanganate spray is, this is usually a sporting process to increase the effect of sand blast. Potassium permanganate solution is sprayed on blasted area of jeans garment with the help of normal spray gun. This potassium permanganate spray appears pink on garment when fresh and turns to muddy brown on drying. The garment is hanged in open to dry after potassium permanganate spray and when the potassium permanganate turns its colors completely then it is considered to ready for next process.

• It is always followed by neutralization process. Sodium Meta bisulphate is most commonly used neutralizer. A number of products are available in market for neutralization process like sodium meta bisulfate selected on the bases of effect required on blasted area

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KMnO4 Spray

1. KMnO4 Spray

• Potassium permanganate spray in best is done in specific spray booths, where rubber dummies are installed for holding garments. Garments are mounted on the dummies and air is filled so the garment is full fit exposed. Specific dummies are used for different sizes and styles, like for kids, trousers, jackets, shirts etc. The booths are fitted with proper air exhaust system. This system leads the spray to treatment room where the chemical mixed air is usually passed through the water showers. Potassium permanganate is dissolved in water and the clean air is blown to open. Shower water is further treated with mild quantities of neutralizer before adding to main drain. But where the potassium permanganate spray is used in low concentrations then there is now need to treat shower water. This mild potassium permanganate mixed water is rather useful for water reservoirs to keep the water clean and germs free.

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KMnO4 Spray

1. KMnO4 Spray – Potassium permanganate spray concentrations ranges

form 0.25 grams per liter to 15.00 grams per liter depending to required results and fabric types. Usually indigo died fabrics are treated with low concentrations whereas Black Sulfur Fabric requires high concentrations to treat with. Sulfur is not much affected with potassium permanganate and hence requires high concentrations and even sometime multiple spray operations. It is more effective to add potassium permanganate brushing to aid the spray effect. It is very important to equip the operator with gloves, gas mask and gaggles. Long time breathing in potassium permanganate spray may cause health complications so proper preventive measures are to be taken for this department.

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KMnO4 Spray

1. KMnO4 Spray

• Garments are mounted on air filled rubber dummies and chemical is sprayed on blasted areas. The variables in spray process are as follow;

• Distance of spray gun to garment- less distance will give more defined and sharp effect where as distant spray will result to more mild and merged effect. Distance ranges form one foot to two and a half foot.

• Air to Water Ratio of Gun- this is to be set very carefully. Low air pressure possibly will through KMnO4 drops on garment resulting to bright white spots whereas high pressure will produce very low bright effect spray effect to areas where it is not required.

• Potassium Permanganate Solution Concentration- of course, this will control the extent to brightness.

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TINTING

• What is TINTING?

After denim pant is being faded, the pants have dyed with very light color(.001% or .002%yellow or pink).This dyeing process is called Tinting/Overdyeing .This process is applied only on garments, not in fabric or yarn. Necessity of Tinting

• For making new fashions. • To give the finished garments a better appearance. • For inventing a new process.

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TINTING

Tinting is a temporary application of color to give a used look. The direct dyes used for tinting do not react with the fabric, where reactive Dyes used for Dyeing make a chemical bond with the fabric. Thus garment dyeing have a good wash fastness and tinting does not. Tinting gives free hand to change the color tone of denim. Excess tint results in a very poor fastness to home laundry.

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TINTING

• Process of Tinting It is a process where very less amount of tint is involved & mainly direct dye is being used to do this process. This is being done to change hue/cast/tone of indigo. As soon as quantity of tint color increases & it cover up indigo, reaches the level of dyeing. Tinting being used to give garments a used / vintage & muddy look. This process takes from 5 minutes to 15 minutes time for better results followed by dye fixing & clean up of superficial dye. Dyeing is being done on very light shade of Indigo, Ecru/ grey denim & Ready for dyeing denim. There are various Types of dyes;

1. Direct Dyes 2. Reactive Dyes 3. Pigment Dyes 4. Sulphur Dyes

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NEUTRALIZATION

Neutralization process in denim

– A process is provided in which manganese dioxide stains in denim fabric which has been partially decolorized with potassium permanganate are neutralized or removed by an aqueous solution of per acetic acid containing at least 1 part by weight acetic acid and 1.5 parts by weight hydrogen peroxide by weight per acetic acid.

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STONE WASH

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STONE WASH

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STONE WASH

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GARMENT WASH

• Garment Wash: • Indigo jeans were once the only item processed by

the garment washing method, but this is no longer the case. A wide variety of different types of woven and knit fabrics dyed by different systems are now used in apparel that is garment washed before retail distribution. Emphasis is on comfort and softness. Also, some fashion trends favor the broken-in look and worn/faded seams that can only be achieved through garment processing.

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GARMENT WASH

Procedure of Garment Washing: 1. Garments can be inverted to minimize unwanted abrasion streaks (especially useful when preset creases are present). 2. Load machine with garments. 3. Desize with alpha amylase enzyme and detergent. 4. Drain. 5. Rinse. 6. Fill machine with water and heat to 60◦C. The liquor ratio can range from 10:1 to 20:1. A number of synthetic detergents can be used. Also, alkaline products such as soda ash or caustic soda can be added in amounts ranging from 0.5 to 2.0 grams/liter. Some chemical suppliers offer special products that accelerate the wash down process, dependent upon the particular dyestuff used. 7. Wash/tumble action for 20-60 minutes, depending upon desired effect. 8. Drain and rinse. 9. Apply softener. 10. Tumble dry. 11. Invert garments, if previously turned. 12. Press, if required. 17

FIXER & SOFTNERS

• Softening and fixing

– To give the soft hand feel to the garment some softeners like silicon or detergents are applied. And for curing or all pre process on denim some resins are applied to fix all effects.

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