Colour Fastness in Textile Testing


Colour Fastness in Textile Testing
Jay Trivedi
Department of Textile Manufactures,
Government Polytechnic, Nagpur, Maharashtra.

What is Color Fastness?
Colour fastness is defined as property of pigment or dye to retain its original hue, especially without fading, running, or changing when wetted, washed, cleaning, when exposed to light, heat, or other influences.

Colour Fastness Test:
  • Colour Fastness to Hot Press
  • Colour Fastness to Water
  • Colour Fastness to Washing
  • Colour Fastness to Rubbing
  • Colour Fastness (SOLVENT)

FASTNESS TO HOT PRESS
  • Scope: This method covers the determination of the amount of fabric stretch.
  • Apparatus: Stretch testing instrument, measuring scale, 4 LB dead weight
  • Sample collection: 1.5 Mt fabric sample immediately after beam gaiting/loom starting
  • Machine used: Washing machine, TMT, and sample dyeing machine ( overflow)
  • Reagent used: Detergent

 Testing Procedure:
  • Cut 10 cm x 4 cm testing sample, place an un dyed cotton cloth of approx. 14*4 cm on flat horizontal surface.
  • Place testing sample over it, place the heated iron 140 C TO 160 C on top and leave it for 15 sec.
  • After 15 second remove the iron and evaluate the change in colour of the testing sample and staining on un dyed cotton piece.

COLOUR FASTNESS TO WATER

  • Scope: This testing is used to determine the colour fastness of fabric to water.
  • Sample collection: Random sampling
  • Sample size: 40 cm full width fabric
  • Atmospheric condition: 70° to 90° F
  • Conditioning timing: Minimum 1 hour
  • Apparatus used: Perspirometer, Air oven, Aluminium  container, Grey scale for assessment.

Testing Procedure:
  • Cut the specimen to the size of 10cm * 4 cm
  • Cut the standard covering fabric to the sample size.
  • Sandwich the specimen between the standard covering fabric and stitch all the four sides.
  • Take distilled water in 1:50 ratio and fully  wet the sandwiched specimen for 30 min.
  • Now place the wetted sample between two plastic plates  and place all plastic plates one above the other.
  • Now transfer the plates on bottom metal plate of the perspirometer.
  • Place the top metal plate and adjust the load with the help of thumb screws.
  • Then keep the loaded instrument in the air oven for 4 hours at a temperature of 38+- 1° C
  • After 4 hours remove the sample specimen from the instrument and remove the stitching
  • Compare the test specimen with the original sample for change in colour compare with scale also.
  • Compare the standard covering cloth with the fresh sample.


COLOUR FASTNESS TO WASHING

  • Scope: This testing is used to determine the colour fastness to washing.
  • Sample collection: Random sampling          
  • Sample size: 40 cm full width fabric
  • Atmospheric condition: 70° to 90° F
  • Conditioning timing: Condition the fabric sample at least for 1 hour before testing.
  • Apparatus used: Laundrometer, measuring jar, balance.
  • Preparation of soap solution: Weight 5 gm of washing soap and dissolve in 1000 ml of water.

Preparation for Testing:
  • Cut the specimen to the size of 10 cm x 4 cm.
  • Cut the standard covering fabric to the sample size.
  • Stitch all the 4 sides by sandwiching the test specimen between the two standard covering fabric.

Testing Procedure:
  • Take soap solution in the ratio of 1:50 (For 1 gm of material 50 ml of soap solution) in the pots of laundrometer
  • Set the laundrometer at 60°C
  • Then introduced the weighed previously prepared specimen in to the pots.4)
  • Start the machine and run it for 30 min.
  • After 30 min take out the specimen and wash with water., then dry in the air oven at temperature at 50 ° C.
  • Take out the soap solution from the laundrometer and compare the same with fresh soap solution and observe for colour bleeding
  • Compare the tested specimen with fresh sample and observe the colour fastness to washing with the help of grey scale

FASTNESS TO RUBBING
  • Scope: This testing is used to determine the colour fastness to rubbing ( DRY and WET)
  • Sample collection: Random sampling          
  • Sample size: 40 cm full width fabric
  • Atmospheric condition: 70° to 90° F
  • Conditioning timing: Minimum 1 hour
  • Apparatus used: BTRA, Crockmeter.

Testing Procedure:

DRY SAMPLING:
  • Cut the specimen having dimension more than 8 x 20 cm.
  • Mount the specimen on the emery paper platform of the instrument lightly avoiding wrinkling or fold.
  • Cut a white cotton fabric having a size of 5 x 5 cm (approximate)
  • Fix the test specimen to the rubbing finger with the help of specimen holder.
  • Place the rubbing finger (with rubbing white cotton) over the sample and give 10 rubs/second by rotating the handle in clockwise only.
  • After 10 rubs remove the white piece and compae it with original white fabric and assessing the staining on white cloth with the help of grey scale.

WET SAMPLING:         
  • Cut the specimen having dimension more than 8 x 20 cm.
  • Mount the specimen on the emery paper platform of the instrument lightly avoiding wrinkling or fold.
  • Cut a white cotton fabric having a size of 5 x 5 cm (approximate)
  • Wet the white fabric with water and squeeze excess water.
  • Fix the test specimen to the rubbing finger with the help of specimen holder.
  • Place the rubbing finger (with rubbing white cotton) over the sample and give 10 rubs/second by rotating the handle in clockwise only.
  • After 10 rubs remove the white piece and compare it with original white fabric and assessing the staining on white cloth with the help of grey scale.
  • After the test dry the white fabric in white condition.
  • Then assess for staining with the help of grey scale.

COLOUR FASTNESS (SOLVENT)
  • Scope: This testing is used to determine the colour fastness to NN DMF/ Acetone/Perchloroethylene (Solvent)
  • Sample collection: Random sampling          
  • Sample size: 40 cm full width fabric
  • Atmospheric condition: 70° to 90° F
  • Conditioning timing: Condition the fabric sample atleast for 1 hour before testing.
  • Apparatus used: Beaker, test tube, measuring cylinder and stopwatch.

Testing Procedure:
  • Take solvent in the ratio of 1:30 (for 1 gm of material 30 ml of solvent) in the beaker.
  • Then introduce the weighed previously prepared specimen in to the beaker.
  • Start the stopwatch and stir it for 3 minutes.
  • After 3 minutes take out the solvent from the beakr and compare the same with fresh solvent and observe for colour bleeding.
  • Compare the tested specimen with fresh sample and observe the colour fastness to solvent with the help of grey scale.
  • Observe the color staining on the standard covering cloth.


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