Colour fastness


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Colour fastness

  1. 1. IMPORTANCE OF TESTING Research and development to enable new and desirable textile products to be produced. Product performance and evaluation to determine if the fabric is suitable for the intended end use. Quality control to ensure that the fabric will be made properly and efficiently. Thus claims and returns will be minimized. Problem analysis to determine why a fabric or textile product is not performing as desired Product comparison to determine which material would be the better value and to prevent wasteful buying. Proper advertising to enable ads to be truthful and not misleading or false Adherence to government regulations so that the textile product can be sold without violating any laws.
  3. 3. COLOR FASTNESSProperty of a pigment or dye to retain its original hue, especially without fading, running, or changing when wetted, washed, cleaned; or stored under normal conditions when exposed to light, heat, or other influences.
  4. 4. Factors Affecting ColorFastness Fiber Type Class of Dye Used Dyeing or Printing Process used Types of Finishing Treatments Used Action Of Laundering Detergents
  5. 5. Qualities Of The Color Evaluator A special individual needed who:  Possesses a knowledge of dyes and pigments.  Knows why color change  Is skilled in colorfastness tests and knows their limitations.  Has the ability to evaluate and report color changes.
  6. 6. Measured Using…Color fastness in• Paper: fadeometer,• Cloth: launderometer.Explained Further…
  7. 7. Types Of Colorfastness Adversely affected by:  Washing  Light  Crocking  Abrasion  Gases in Atmosphere  Frosting  Perspiration  Heat
  8. 8. GRAY SCALE Arrangement of Achromatic gray chips in a scale from light to dark. Nine pairs of non-glossy neutral grey coloured chips, which illustrate the perceived colour differences. give a corresponding fastness rating of 5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, and 1)
  9. 9. Using A Gray Scale… Uses a class 5-4-3-2-1 rating system. Class 5 best, Class 1 worst. Half Rating, such as 3-4 also used. 5-Excellent, 4-good, 3-fair, 2-poor, 1- very poor. Specimens of a given hue are matched against these gray chips. They equate differences in lightness with differences in color.
  10. 10. Methodology Of Testing.. A control fabric is used, usually white or un-dyed; also assessed for the staining which results from contact with the test material. Results assessed by grading against standard A04/A05 greyscales Grade of 5: no change in colour, staining Grade of 1: substantially different.
  11. 11. Methodology Of Testing(Contd).. Usually only one specimen of fabric used. If material dyed or printed uniformly throughout the fabric, then specimen chosen should be representative of entire lot. For multi –colored printed fabric, each color should be tested in order to evaluate every color.
  12. 12. Gray Scale For Staining… Used to evaluate a fabric’s resistance to staining. Normally a multi-fibre strip of 6 fibre components used for staining test: Acetate, Cotton, Acrylic, Polyamide, Polyester and Wool. Same as the other gray scale, except for the chip in each pair that remains the same is a standard white. Various contrasting pair of chips are given numerical color fastness ratings, from class 5 to class 1. Utilizes samples of undyed fabric to determine if a colored fabric will stain an adjacent fabric.
  13. 13. Multifibre Fabric Strip
  14. 14. Grey Scales for Staining
  15. 15. Grey Scales For Coloring
  16. 16. Limitations Of Grey Scale Disagreement when bright colors are used. Works well with most colors otherwise.
  17. 17. CHROMATICTRANSFERENCE SCALE  used to evaluate fabrics resistance to crocking.  six sets of color chips.  Each set is graduated from light to dark with different rating.
  18. 18. Lighting Used For Evaluation When visually evaluating or comparing, standardized light source should be used. COLOR MATCHING BOOTH frequently used for color checking.
  19. 19. COLOR MATCHING BOOTH Contains 4 different standardized lights:  Daylight  Incandescent Light  Cool White Fluorescent Light  Ultraviolet Light Each used to view specimens by pushing a switch. Daylight used when evaluating colorfastness as color appears closer to way usually seen.
  20. 20. COLORFASTNESS TOWASHING Ability of the fabric to with stand the effect of laundering. Launder-ometer is used to evaluate colour fastness to washing with the help of grey scales. The washing of fabric results in the removal of dye, therefore staining can occur, inorder to determine the staining, a white multifiber strip is attached to the specimen being tested for CF to washing. The staining effect on each fiber in the multifiber test fabric should be rated using the grey scale for evaluating staining. It is checked afterwards for the effects of bleeding or colour migration. AATCC standard detergent 124 used.
  21. 21. The Laundrometer Specimen placed in a metal cylinder containing water, detergent, steel balls, and chlorine. Rotating action of these cylinders produces the same effect as textile products being laundered.
  22. 22. Testing Procedure: Overview The specimen is placed in a metal cylinder in which water, detergent, metal balls and chlorine are placed. The amount of detergent ,temperature, agitation and bleach can be controlled.
  23. 23. TEST PROCEDURESPECIMEN PREPERATION: Cut the specimen 2 x 6 inches, stapled with the multi fiber fabric.PROCEDURE: Place the sample in the container along with the steel balls and detergent Run the machine for 45 minute After taking the specimen rinse it with water and soak it in acetic solution and rinse it again with water. Remove the excess solution Dry the specimen and test fabric together using an hand iron Remove the test fabric and compare it with the gray scale to find the fastness.
  24. 24. Process Diagram
  25. 25. COLORFASTNESS TO LIGHT This refers to the ability of the fabric to withstand the sun light. The resistance of the sunlight depends on:  the intensity of the light  inherent properties of the fabric.  Season  altitude  distance from the equator.
  26. 26. Measurement Method Original standard method: Sunlight method  samples are placed in a glass cabinet and exposed to sun light from 9 am-3 pm. It is time consumable process. Weather-o-meter and Fade-o-meter most widely used instruments. Both this instruments use different light source and the temperature and humidity are controlled with in the machine Specimens placed around the light source , and remain there until the end of test. Then evaluated as to changes in color resulting from radiation Weather-o-meter is a newer and more versatile machine It enables specimen to be sprayed with water during the test, if desired. It also is able to alternate light and dark periods if continuous light exposure is not desired. These conditions are used in the Weather-o-meter to test fabric for such end uses as outdoor furniture, tents or rainwear.
  27. 27. Instruments and Fastness… Both machines have either a carbon-arc lamp or a xenon- arc lamp as the light source. The degree of fastness required depends on end use.As an example, a coat material should have more color fastness than a colored dress shirt. Similarly clothes not intended to worn outside should also have certain color fastness to enable drying in sunlight.
  28. 28. WEATHER-O-METER  Newer, versatile.  It enables the specimen to be sprayed with water if needed.  It also manipulates the light and dark period if continuous exposure is not needed.  These make it most suitable for testing fabrics for end uses like outdoor furniture, tenting or rainwear.
  29. 29. Using Weather MeterTwo testing methods are used: Time method Standard fading method
  30. 30. TIME METHOD  The specimen is exposed to light for a particular amount of time.  After the termination of time the specimen is taken out and evaluated.Disadvantage Specimen is not exposed to the same amount of light each time the test is performed.
  31. 31. Test ProcedureSpecimen Preparation Cut the specimen 2.5” x 8” with the longer dimension in lengthwise.Test Procedure Mount the specimen in the cardboard holder and remove the perforated strips so that half of the specimen area will be uncovered. Insert the cardboard holder into the metal holder and place in to the machine. Expose the specimen for 20 hours. At the end of the desired exposure time period, remove the specimen and allow it to relax in the dark at room temperature for atleast 2 hours in order to regain moisture from the air. Using the grey scale for evaluating colour change, determine the colour fastness rating for the test fabric.
  32. 32. COLOR FASTNESS TOCROCKING The rubbing off of colors is called as crocking. Fabrics with large amount of surface dyes like dark color cotton fabric tend to have poor colorfastness to crocking, pigment dyed or printed fabrics also face the same problem. Some time in order to increase the depth of the colors the surface dyes are not washed off which also results in crocking.
  33. 33. Crock Meter  The crock meter is used to find the color fastness to crocking.  This instrument has a finger covered by a white cotton fabric which would rub against the specimen.  This test should be performed both as wet and dry test.  The wet test is an severe test since moisture helps in removal of dyes
  34. 34. COLOR FASTNESS TO CROCKING ProcedureSpecimen Preparation Cut two specimens on the bias, 8”x8” and place the test specimen on the crock meter so it will be rubbed in the bias direction. Test Procedure Mount a dry, white crock test cloth over the finger section of the crock meter so that it will be rubbed in the bias direction. Lower the covered finger, causing the crock test cloth to slide over the coloured specimen for 10 complete cycles. Remove the specimen and the white crock test cloth. Perform a wet crocking test by the same procedure. Rate the crock test cloths using the colour transference chart.
  35. 35. COLOR FASTNESS TOPERSPIRATION.  Perspiration can cause a fabric to change color as well as resulting in staining of adjacent material.  The test is attempted to stimulate the actual condition. the specimen is heated for 6 hours at 38°C .  A multifibre test fabric is placed against the specimen, the test is carried out and later evaluated for bleeding or color migration.  After the test is completed ,the specimen is evaluated using the gray scale and the average rating is reported.
  36. 36. Diagram Perspiration tester
  37. 37. TEST PROCEDURESPECIMEN PREPERATION: Cut the specimen of 2 ¼” x 2 ¼” Cut the multifiber fabric to 2 x 2 inchPROCEDURE: Immerse the test sample and the specimen in the acid solution for 15 min. With draw the fabric and remove any excess liquor Place the specimen in the perspiration tester Load the tester with 10 pounds of pressure. Place the loaded tester in an oven and heat it to 100*f for 6 hours Remove the tester from oven and allow the fabric to dry at room temperature. Remove specimen and test cloth and Compare with gray scale.
  38. 38. COLOR FASTNESS TO FROSTING Frosting is the change of color caused by a localized , flat abrasive action. Fabrics that have poor dye penetration possess poor colorfastness to frosting. Fabric that are cross dyed also possess poor color fastness (due to differences in the abrasion resistance) .
  39. 39. Difference Between Crocking Test andFrosting Test Crocking evaluates the appearance of the specimen Frosting only evaluates the rubbing cloth, not the specimen.
  40. 40. COLOR FASTNESS TO GASES INATMOSPHERE The dyes in the textile material are affected to a various degree by atmospheric gases. The major cause for this is due to the reaction of disperse dye with ozone and oxides of nitrogen. The disperse dyed with acetate fabric has the maximum effect while nylon, polyester, acrylic has low effect. Inhibitors are used for this purpose but are not permanent. Darker, brighter change more dramatically. Typical changes: Blues turning pinkish, browns turning reddish, greens turning brownish.
  41. 41. Instruments Used GAS FADING CHAMBER:-tests the effects of oxides of nitrogen. OZONITER (ozone exposure chamber):-tests the effect of ozone.
  42. 42. General Procedure The specimens are placed in the gas filled chamber for a particular time along with the control fabric. The tests are conducted at 140*F for approximately 2-3 hours. The relative humidity is normally kept low due to the heating of gases. Gas fading termination: when blue sample turns a specific purple color. Ozone fading test: gray sample turns a standard brown color
  43. 43. Gas Fading Chamber
  44. 44. TEST PROCEDURESPECIMEN PREPERATION: Cut the specimen 2 x 4 inches ,with the long direction length wise Cut the blue acetate control swatch 2 x 2 inches longTEST PROCEDURE: Place the specimen(2x4inches)and control sample(2x2inches)in the gas fading chamber. Heat the chamber to about 140*f by using Bunsen burner. Leave the specimens in the chamber until the color changes from blue to purple. Change the control sample and repeat the procedure (only for ozoniter test, sample changes from grey sample turns brown. Using The Gray Scale Determine The Color Fastness Rating.
  45. 45. TEST PROCEDURESPECIMEN PREPERATION:Cut two circular specimen of 4 ½ inches (emery method)Cut two circular specimen of 5 inches (screen wire method)PROCEDURE(EMERY METHOD): Place the emery paper and the specimen on the tester The pressure on the diaphragm is set to be 3 psi and place a 3 pound load on the head. Start the tester and allow it to run for 100 continuous cycles. Remove the specimen and vaccum it n order to remove fibre and abradant residue. Hand rinse the specimen by bolting it between two white cotton fabric hand iron at 300*f. Repeat the procedure for other specimen, using gray scale find the color fastness.
  46. 46. Diagram of gas fading chamber
  47. 47. COLOR FASTNESS DUE TO HOTIRON The change in color of the garment due to hot iron and dry heat can be found by Contact Heat Tester.
  48. 48. CONTACT HEAT TESTER  The heat contact tester consist of 3 pairs of individually controlled heaters  allows simultaneous testing of 3 differing temperatures in the range 100°C to 230°C.  After the allocated time the specimens are taken out and is compared to the gray scale from which the color fastness is found out
  49. 49. COLOR FASTNESS TO WATERSAMPLE PREPERATION: Cut the specimen and the multi fiber specimen of 6 x 6 cm and sew it together.PROCEDURE: Place the specimen in a Petri dish and add distilled water to a depth of 1.5 cm Soak the specimen at room temperature for 15 min with occasional agitation After removing the excess water place the specimen in perspir-o-meter with a load of 10 pounds. Place the total unit in the oven at an temperature of 38*c for 18 hours Remove he specimen from the oven and dry it at standard atmosphere. Compare the sample with the gray scale to find the fastness.
  50. 50. Shade Matching….
  51. 51. What Makes One Perceive Color ? Light falls on the object and is partially absorbed. The light that is not absorbed is reflected and falls on the color receptors in the eye. The receptors convert the incident light into stimuli, which are then conducted via nerves to the brain. Here the stimuli are interpreted and a color perception is formed
  52. 52. How are colors defined ?Three numerical values: Hue The actual color of the sample.  Similarity of one or a mixture of one or more colors out of the primary ones. Value  Property that arises out of the fraction of incident light being reflected from the sample.  Saturation Of Color Chroma  View at a given illuminance level.  Brightness of the Sample Form the basis of colourimetry. Human eye can perceive light wavelength of 350 to 750 nm .
  53. 53. VALUE 10P(89) 10RP(01) 10PB(75) 10R(11) 10YR(19)HUE10B(65) CROMA 10Y(31) 10BG(57) 10G(49) 10GY(41)
  54. 54. Color order system Any systematic rational method of arranging all possible colors or subsets by means of material samples selected so that they represent all object color.
  55. 55. NEED FOR COLOR ORDERSYSTEM Human Inability to distinguish between tens of millions of shades perceived.
  56. 56. Merits of color order system Realistic, easy to understand. Standard viewing conditions. No instrument required. Calibrated in terms of tristimulus values. Visually uniform color spaces, such as Munsell and OSA can prove a useful way of organizing the colors of a digitally controlled color television monitor.
  57. 57. Demerits of color order system Not easily convertible amongst the wide varieties available. Difference between the intended aim color and actual color of the physical samples quite high for an atlas. It is not possible to include all perceivable colors in any color order system. The appearance of larger samples of identical color notably different. Difficult to compare samples with color standards of different texture and material.
  58. 58. Type of color order system Munsell color order system OSA color order system Chroma cosmos CIE colorimetric system RAL system Practical color coordinate system OSA-UCS system etc.
  59. 59. COLOR MATCHING Color matching can be done in two ways:  Visual color matching under illuminant.  Computerized color matching system (Spectro photometer)
  60. 60. Process Of Color Matching Basic information needed:  light source  fabric quality  Specific requirements (process flow)Visual color matching Shade matching is done under light box in a darkroom. Both standard and sample are placed under same illuminant and matched visually. A trial and error method.
  61. 61. Light Viewing CabinetsBy Gretag Macbeth
  62. 62. Different Light sources Illuminantsstandard light sources defined by specific spectral power distribution(SPD). These may be:  Natural day light  Tungsten lamp  Tungsten-Halogen Lamp  Carbon arc lamp  Mercury and sodium vapor lamps  Xenon arc lamps  Fluorescent tubes  Lasers  UV lamps  Cool white
  63. 63. Lab Facilities for ColorMatching Spectrophotometer
  64. 64. Process for color matching inSpectrophotometer Standard shade fed to the spectrophotometer by measuring its reflectance value. difference of the reflectance value(DE) obtained. DE should be as close as possible to standard shade.
  65. 65. Working of spectrophotometer
  66. 66. Wavelength (nm) Reflectance (%) wavelength
  67. 67. DE Measurement Two methods present:1)Lab method, DE= sqrt[(dl/l)^2+(da/a)^2+(db/b)^2]2)Lch method, DE= sqrt[(dl/l)^2+(dh/h)^2+(dc/c)^2] dL=Value da=red or green values (RGB Value) db=yellow or blue relative values dc=Chroma dh= Hue
  68. 68. Color development by CCM Based on the reflectance value computer will calculate some recipes of different dye stuff which may ultimately produce the desired colour Colour matching is a trial and error method. The shade which was produced by computer prediction may not match under particular light source which are checking visually in the light cabinet. If the shade doesn’t match with the standard then a second attempt is taken with the help of CCM or by visual analysis.
  69. 69. Read X,Y,Z of std & data for dyes & substrate Select a new combination of 3 dyes Calculate C1,C2,C3 For 3 dyesYES Negative conc. Or outside tolerance? NO Calculate reflectance & XYZ value for formula Calculate new Conc. from ΔXYZYES Compare XYZ values close enough? NO Calculate colour difference under different illuminants (metamerism) & cost YESNO All possible combinations covered? OUTPUT
  70. 70. Metamarism A colored object appears to be one colour under a given light source such as daylight, but appears to change colour under another light source five types:  Illuminant  Observer  Geometrical  Field-size metamerism  instrumental metamerism
  71. 71. Metamarism
  72. 72. Methods for Shade Development Cold Pad Batch (Silicate/Soda Ash/Mixed Alkali) Pad Dry Chemical Pad Steam (Reactive & Vat Dyes) Pad Steam (Reactive Dyes) Wet on Wet (Reactive & Vat Dyes) Pad Dry Cure (Caledon Dyes) Pad Thermosol (Reactive ECONTROL & PES/CO Blends)
  73. 73. Discussion…For each of the following garment, give 3 color fastness tests which would determine if the indicated dyed fabric is suitable for the end use: • 100% nylon bathing suit • 100% acetate summer daytime dress • 100% wool winter coat • 100% acrylic winter sweater
  74. 74. Discussion…Which Rating is better for colorfastness to light for a woman’s summer dress: Class 5- 20 hours Or Class 4- 40 hours?
  75. 75. Thank You.