Color Fastness to Hot Pressing

Last Updated on 25/12/2021

Color Fastness to Hot Pressing:
Hot pressing fastness test of dyed and printed textile products is performed to determine of resistance of textiles to ironing and to processing on hot cylinders. Different tests are performed according to when the textile is dry, when it is wet, and when it is damp.

Purpose and Scope:
Color fastness to hot pressing method is used for determining the resistance of the color of textile of all kinds and in all forms to ironing and processing on hot cylinders. Tests are given for hot pressing when the textiles are wet, when it is damp, and when it is dry. The textile end use usually determines which tests should be made.

Therma plate for Color Fastness to Hot Pressing
Fig: Therma plate for color fastness to hot pressing

Apparatus and Materials:

  1. Heating device, providing even heat transfer to the specimen from the top by close contact at a controlled temperature and giving a pressure on the specimen of 40±10 g/cm2.
  2. A smooth heat resistant sheet.
  3. Wool flannel of approximately 260 g/m2. Two layers of this material are used to make a pad of approximately 3 mm thickness. Similar, smooth wool fabrics or felt to give a pad about 3 mm thick could be used.
  4. An undyed, bleached and not mercerized cotton cloth, with a smooth surface 100-130 g/m2.
  5. Gray Scale for Color Change.
  6. Gray Scale for Staining.

Important Points for Hot Pressing Fastness Test:

  1. Hand iron of proper weight to give a pressure of approximately 30g/ at the temperature indicated in the following ;
  2. Cotton and Linen 190-200˚C
  3. Wool, Silk and Viscose 140-160˚C
  4. Cellulose acetate and Polyamide 115-120˚C
  5. White bleached cotton cloth weighting approximately 125g/sq.meter. Five pieces not less than 14×4 cm are required.
  6. Gray scale by assessing change in color and staining (ISO scale).
  7. The size of the specimen is 10×4cm

Specimen Preparation:
Specimen of materials, which has been subjected to any heat or drying treatment, must be allowed to condition at 65% RH, temperature 20±2˚C, before they tested. Three specimens for each color and material measuring 4 cm x 10 cm; one for dry pressing, one for damp pressing, and one for wet pressing.

Working Procedure of Color Fastness to Hot Pressing:

Dry Pressing:
The dry specimen is pressed with a heating device of a specified temperature, time and weight. Place the specimen on the piece of dry cotton cloth on a smooth horizontal surface. Place the iron on the specimen and leave it for 15 Sec.

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Damp Pressing: 
The dry specimen is covered with a wet, undyed cotton cloth and pressed with a heating device of a specified temperature, time and weight. The adjacent fabric in dimensions of 100 mm x 40 mm is immersed into the water and, squeezed as 100% pick up. Dry specimen is placed onto the undyed cotton fabric on the filler and, the wet adjacent fabric is placed onto them. The top layer of the device is pulled down and, dry specimen is pressed for 15 seconds at the determined temperature. The change in color of the specimen is evaluated in two different ways according to grey scale.

  • Soon after the end of the test
  • After conditioning for 4 hours under standard atmospheric circumstances.

The staining to undyed fabrics is evaluated by grey scale.

Wet Pressing:
The wet specimen is covered with a wet, un-dyed cotton cloth and pressed with a heating device at specified temperature and weight. Soak the specimen and cotton cloth in distilled water and squeeze or extract them to contain their own weight of water. Place the wet specimen on a piece of the dry cotton cloth and place the wet cotton cloth on the specimen, press by moving the iron to and fro over the wet cloth (without additional pressure) for 15 sec.

Assess the change in color of the specimen with appropriate grey scale.


  • Dry Pressing 4
  • Wet Pressing 3-4

Evaluation and Classification:
For determining change in color, samples are evaluated immediately and after the sample have been allowed to condition for 4 hours at 20˚C, using the gray Scale for Evaluating Color Change, and staining.

You may also like:

  1. What is Color Fastness | How to Improve Colorfastness | Importance of Color Fastness
  2. Different Types of Colour Fastness Test | Factors Affecting Colour Fastness
  3. Gray Scale for Color Change and Color Staining
  4. Colour Fastness to Washing Procedure (ISO 105 C06)
  5. Various Fastness Methods Given to the Dyed Material
  6. How to Determine colour Fastness to Wash
  7. Light Fastness of Textiles: Factors Affecting and Control Measures
  8. Colour Fastness to Laundering Test
  9. Factors Affecting the Rubbing Fastness of Textile Materials
  10. Colour Fastness to Water Test Method (ISO 105 EO1)
  11. Color Fastness to Sea Water (ISO 105 E02)
  12. Color Fastness to Perspiration Test Method
  13. How to Improve the Fastness Properties of Pigment Printed Cotton Fabric

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