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Assesment of colour fastness

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Colour fastness
Colour fastness
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Assesment of colour fastness

  1. 1. Presentation by:- Rashmi.R 1st MHSc (TAD )
  2. 2.  Assessment of Color Fastness in Textiles
  3. 3.  Fastness is the resistance of a textile material to specific chemical agencies. Poor color fastness in textile products is a major source of customer complaint. The fastness of a color can vary with the type of dye, the particular shade used, the depth of shade and how well the dyeing process has been carried out. Dyes can also behave differently when in contact with different agents, for instance dyes which may be fast to dry-cleaning may not be fast to washing in water. It is therefore important to test any dyed or printed product for the fastness of the colors that have been used in its decoration. Fastness
  4. 4.  Colorfastness A distinction should be made between dyeing(internal pigmentation) and printing(external pigmentation). The buyer has a right to expect dyed fabrics to withstand the deterioration elements or influences to which the finished cloth will be subjected such as:- Sunlight Perspiration Washing Friction
  5. 5.  Evaluation of fastness properties of a dye is done by measuring:- Washing- Wash Wheel Light- Xenoster Rubbing - Crock meter Perspiration- Perspirometer Evaluation of Fastness Properties
  6. 6.  Fastness To Sunlight  XENOMETER XENOSTER •This is used to test the light fastness of the dyed fabric. •color fastness to light, By Xenotester
  7. 7.  Commercial testing agencies frequently use standard tests to light fastness specially designed powerful carbon arc lamp has the same effect as that of sunlight. Samples to be tested revolved around this lamp for definite period of exposure.  After processing, comparison in the change in color of the specimen with the changes that have occurred in the standard pattern under suitable illumination is carried out to determine the fastness of light. Function of Xenometer
  8. 8. The best way in which to determine fastness to launder a fabric. A10 x 4 cm swatch of the dyed fabric is taken and is sand wiched between two adjacent fabrics and stitched. The sample and the adjacent fabric were washed together. Five different types of washing are specified as different washing methods. •The solution should be preheated to the required temperature of washing. After soaping treatment, the specimen is removed, rinse twice in cold water , Squeezed and dried in air at a temperature not exceeding 60°C. the value is evaluated with the help of grey scales. Fastness to Laundering
  9. 9.  Features of Washing Fastness Tester:-  •It is fabricated out of quality stainless steel.  •Possess electric heater to heat water in water bath.  •The microprocessor based programmer is provided for temperature control.  Buzzer to indicate the completion of the process cycle or step. WASH FASTNESS
  10. 10.  WASH FASTNESS TESTER
  11. 11.  FASTNESS TO RUBBING  The test is quite:- Sensitive and for getting consistent result, it is necessary to use  Standard crock meter  Cloth,  Maintain uniform pressure for applying rubbing strokes and number of strokes.
  12. 12.  Crock meter is used for testing the transference of color from the surface of one material to another by either wet or dry rubbing.
  13. 13.  In this there are two types of Crocking:- Dry crocking:- A 2” square of colored fabric rubbed against a piece of white sheeting. Any discoloration of the fabric itself, the color is not fast to dry crocking. Wet crocking:- A piece of white sheeting should be dampened and rubbing against the piece of untested colored fabric. Any discoloration of the white cloth should be noted. If this occurs, the color is not fast to wet crocking. COLOUR FASTNESS TO RUBBING
  14. 14.  Fastness to perspiration  •The fastness of colored fabric with reference to alkaline and ac idic perspiration was evaluated. For the alkaline (pH‐8) and aci dic (pH‐5.5) liquors were prepared and the composite specimen s were dipped in acidic and alkaline solution separately for 30 minutes. Good and uniform penetration of the solution was ens ured. The liquor was poured off and the excess water and air b ubbles, if any were removed by passing the specimens in betwe en two glass rods. Composite specimens were then placed bet ween glass/acrylic plates with a pressure of 12 kpa per spirometer.  The perspirometer,was kept for four hours at a temperature of 37 ( ±20C). Afterwards, the fabrics were removed, separated and drie d in air below 60°C. The values were rated as per the grey scale. T he details of the values assigned for these properties are:
  15. 15.   •5 =Negligible (Excellent)  •4 =Slightly changed (Good)  •3 =Noticeable changed (Fairly good)  •2 =Considerably changed (Fair)  •1 =Much changed (Poor) The values were rated as per the grey scale. The details of the values assigned for these properties are:-
  16. 16.  Perspirometer
  17. 17.  There are two types of pressing:- Hot pressing Wet pressing Color fastness to Pressing
  18. 18.  Hot pressing
  19. 19.   Soak the test specimen and a piece of cotton adjacent fabric in distilled water and squeeze it to maintain 100% pick up.  Place the soaked cotton fabric on top of the dry test specimen and repeat Wet pressing
  20. 20.  COLOUR FASTNESS ASSESSMENT BY USE OF GREY SCALE
  21. 21.  A different set of grey scales is used for measuring staining. Fastness rating -5 is shown by two identical white samples and rating 1 shows a white and a grey sample. The other numbers show geometrical steps of contrast between white and a series of greys. A piece of untreated, unstained, undyed cloth is compared with the treated sample that has been in contact with the test specimen during the staining test and a numerical assessment of staining is given. A rating of 5 means that there is no difference between the treated and untreated material. If the result is in between any two of the contrasts on the scale, a rating of, for example, 3-4 is given. Sets of grey scales, examples of which are shown in Fig: can be supplied by the British Standards Institution.
  22. 22.  References:- Wingate Isabel Barnum and Mohler, Textile Fabrics and their selection Book,1984 , New Jersey, page (187-192). textilelearners@gmail.com- Google search engine
  23. 23. THANK YOU…………

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