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Friday 24 February 2012

Introduction of Pressing Fastness Test | Color Fastness to Pressing

Posted at  23:15  |  in  TTQC

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


Purpose and Scope:
This method is used for determining the resistance of the colour 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.

Apparatus and Reagent
 
  • Hand iron of proper weight to give a pressure of approximately 30g/sq.cm at the temperature indicated in the following ;
  1. Cotton & Linen 190-200C˚
  2. Wool, Silk & Viscose 140-160C˚
  3. Cellulose acetate & Polyamide 115-120C˚
  • White bleached cotton cloth weighting approximately 125g/sq.meter. Five pieces not less than 14×4 cm are required. 
  • Gray scale by assessing change in colour and staining.(ISO scale)  
  • The size of the specimen is 10×4cm
Working Procedure
Specimen preparation
Specimen of materials, which has been subjected to any heat or drying treatment, must be allowed to condition at 65% RH, temp. 20±2C˚, before they tested.

Dry Pressing

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.

Damp Pressing: 
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.

a) Soon after the end of the test
b) After conditioning for 4 hours under standard atmospheric circumstances.
The staining to undyed fabrics is evaluated by grey scale.

Wet Pressing

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.

Assessment
Assess the change in colour of the specimen with appropriate grey scale.

Standard
Dry Pressing 4
Wet Pressing 3-4 

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