Fundamentals basic terminologies in dyeing
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Fundamentals basic terminologies in dyeing
- 1. FUNDAMENTALS:BASIC TERMINOLOGIES USED IN DYEING BY B. Venkatesh Asst. Professor, Dept. of Textile Technology VFSTR University
- 2. • DYE AFFINITY • Attraction of the dye to the fibre or the tendency of the dye to go on the fibre on its own without any external influence of heat or chemicals • EXHAUSTING AGENTS • which help in transferring the dye molecules inside the fibre or fabric structure • % SHADE • Example: 4Kgs of dye is taken for dyeing of 100 Kgs of material, it is said to be dyed with 4% Shade. • It can be easily calculated as, • % Shade = (Wt of dye taken for dyeing / Wt of material) X 100 = (4kgs / 100Kgs) X 100 = 4%
- 3. • M.L.R. • Example: When 100 Kg of material is dyed by using 1000 litres of Liquor (chemicals + water), the MLR is 1:10 • RETARDING OR LEVELLING AGENTS • Dyeing assistants are added in the dye bath which gets combined with the dye to form a loose complex. • It cannot enter the fibre or fabric structure. • However, this complex has to be broken subsequently. • Generally by raising the temperature so that the dye is again made available, but gradually for the dyeing process. • These assistants slow down the rate of dyeing and help to produce level dyeing results; they are called retarding agents or levelling agents.
- 4. • SATURATION DYEING • If we go on increasing the % Shade of dyeing at certain depth, the fibre will get saturated with the dye • There will be no further increase in the depth, while the excess dye remains in the dye bath
- 5. • RATE OF DYEING • It is the amount of dye transferring into the material per unit time. • APPARENT DEPTH • This is the actual depth (or shade) which you get after completing the dyeing process. • ON-TONE DYEING • When the tone of the fabric is not changing with time only depth increases
- 6. • % EXHAUSTION • The dye uptake of the fibre during dyeing is expressed in terms of % Exhaustion of the dye bath. • % of the amount of dye goes into the fibre during dyeing from the initial amount of dye taken. • Thus if a dyebath contains ‘x gm/ltr’ of the dye before dyeing and ‘y gm/ltr’ at the end of dyeing, • % Exhaustion = (x – y / x) X 100 • Example: if 2 Kgs of dye is taken for dyeing and only 1 kg of dye actually transferred onto the fibre while the remaining 1Kg is left behind in the dye bath than it is said to have attained 50% Exhaustion.
- 7. • % EXPRESSION OR % WET PICK-UP • It is the amount of liquor in gms carried by per 100gms of fabric after passing through the padding mangle, which is expressed as a percentage. • Example: 1 Kg of fabric is padded on a mangle and after passing through the mangle if the weight of the fabric rises to 1.7 Kg. 0.7 Kg of liquor is than expressed as % to the initial weight of the fabric • % Expression = {(Final Wt of Fabric – Initial Wt of Fabric) / Initial Wt of Fabric} X 100 = (1.7 Kg – 1 Kg / 1) X 100 = 0.7 X 100 = 70 %
- 8. • % OWM (On Weight of Material) • The amount of chemicals in gms to be used per 100 gm of material is called % OWM. • Example, for 5% OWM Na2CO3, 5gms of Na2CO3 is to be used per 100gm of material • GPL (Grams per Litre) • The amount of chemical in gms to be used per one litre of liquor is called gpl. • Example, for 40 gpl NaCl, 40gms of NaCl is to be used per 1000ml of liquor.
- 9. • COLOUR FASTNESS • It can be defined as the dye or colour present on the material after the dyeing process should not easily come out during • washing, • rubbing, • exposing to light, • perspiration, • saliva etc..
- 10. THANK YOU