ITC Logo Cambodia Export Diversification and Expansion Program

ITC Logo Cambodia Export Diversification and Expansion Program (CEDEP I)/High Value silk project Training for Synthetic Dyeing of Silk Yarn and Fabrics Chomnab HO National consultant Phnom Penh, June 4 -5, 2014

Color Theory - Primary color Secondary color Tertiary color

Color Matching

Calculation We need to know a basic of calculation in order to compute dye stuff and other auxiliary substances. The basic calculation of the proportion or ratio for dye stuff. For example: - Blue 0. 5% - Green 0. 3%

Measurement Unit Kilogram Hectogram Dekagram Decigram Centigram Milligram 0 1 0 0 0 Gram 1 0 0 0 1

Using the scale ON/OFF UNITS RE-scale Warning: Check the capacity of the scale before using. Over capacity usage damages the scale

Degumming Silk material is immersed for 30 mm to 90 mm at 100 0 C in the degumming solution consisting of the following chemical: – 15% Dish washing Soap – 5%- Soda Ash – 2% Sodium hydrosulfite • water (liquor ratio of 1: 30) • Percentage of each chemical was based on the weigh of the materials to be dyed

Flow Process of Degumming Silk Fabric Degumming at the boil Dish washing Soap Sodium hydrosulfite Soda Ash 30 -90 mm. Water. LR 1: 30 Temperature 100 0 C 10 mins 70 0 C 100 0 C Drain Wash 6 x at gradual Temperature

Neutralization 1. Measure the same amount of water using liquor ratio (L/R) 1: 30 2. Add 2 ml/L glacial acetic and mix thoroughly 3. Soak for 15 minutes at room temperature 4. Drain the solution, wash and dry the material.

What is Dyeing? It is the process of imparting color to the material. Purpose of Dyeing • Impart attractive hue on the material • Enhance the aesthetic quality of material • Increase the value or cost • Cope up with the growing demand of fashion in the global market

Factors Affecting Good Exhaustion • Dyestuff • p. H of the dyebath • Dyeing temperature • Dyeing time • Types of fibers • Process Used

Common Dyeing Process • Basic Dyeing – Most commonly used dyes for handicraft products and acrylic – Almost all indigenous fibers can be dyed with basic dyes – High coloring power and marked by brilliance of shades • Low breaking strengths – Nylon, silk, wool, etc can be dyed acid dyes – Good colorfastness to light and washing.

Common Dyeing Process • Reactive Dyeing – Good Colorfastness property – Best for cellulosic fibers specifically cotton, rayon, abaca and pineapple • Disperse Dyeing – For dyeing polyester

Common Problems • Inaccurate weights of raw materials, dyestuffs, auxiliaries and chemicals • Insufficient treatment time • Inappropriate treatment temperature • Inadequate washing • Inappropriate ratio of material to water

Acid Dyeing Flow Chart Glauber’s salt Material to be dyed X% dyestuff Acetic Acid (0. 6 g/l) Drain Temperature : 100 0 C Duration: 30 -60 mm 70 0 C Rinse

ACID DYEING PROCEDURE 1. Weigh the dried pretreated material. 2. Compute and measure the amount of water needed based on a liquor ratio. 3. Compute and weigh the required chemicals. 4. Pre-dissolved the dyes and each of chemicals by taking some amount of water measured in step 2. 5. Add required amount of glacial acetic acid to the measured water in step 2 to obtain p. H 4 -5 Stir thoroughly. 6. Soak materials in the solution for 10 minutes. 7. Remove or lift the materials then add pre-dissolved dyes. Bring the solution to a boil. 8. Remove or lift the materials then add glauber salt. Continue boiling for 30 minutes – 1 hour 9. Drain solution, wash materials until water is clear of dyes. Then air dry.

Sample Computation • Weigh of materials = 500 g liquor ratio = 1: 30 Volume of water = weigh of materials x LR = 500 x 50 ml/g = 25, 000 ml or 25 L • Weigh of Glauber salt = 10 g/L x 25 L = 250 g • Weigh of dye (2. 5%) = (2. 5%/100)x 500 g = 12. 5 g • Weigh of 40% acetic acid = 12. 5 g

Color Fastness Customers always want high quality of products. Producers have to ensure the products are high color fastness. Fixing process is required for some colors which have low color fastness, for example, turquoise. Process of color fixing: 1. compute and measure the amount of warm water needed based on a liquor ratio 1: 15 2. Compute Laverfix 50 -100 g/l 3. Add the amount of laverfix into the water and stir thoroughly. 4. Immerse silk yarn or silk fabric into the solution and soak for 20 mm 30 mm 5. Drain, hang and air dry in the shade. 6. Check the dried silk yarn or fabric to ensure high color fastness.

Precautions in dyeing • Chemicals, if not handled properly, maybe poisonous and irritating to the eyes and skin. • All fine powders whether toxic or not, are potentially harmful if inhaled. • Mix acid to water never water to acid. • Do not eat, drink and smoke while using chemicals. • Keep pots, pails, tongs, measuring devices and basins solely for pretreatment and dyeing. Never use the same equipment for food preparation or cooking. • Wear rubber gloves and face masks when using corrosive and toxic chemicals. • Always work in a well-ventilated place • Azo dyes when in contact with skin are carcinogenic.

Sample of dye information sheet Date: ………… Raw material: ………… Weight: ……………. . Liquoration…………… Dye stuff use…………. Formula ……………………………. % Auxiliary use Acetic acid……………………. . g/l Glauber salt………………. . . g/l Sample of colored yarn/fabric