Sunday, 15 May 2011

Some Selected Notes on Textiles- Part 2



- Acid dyes are used for silks. There are three categories of acid dyes- Leveling or strong acid dyes, Milling or weak acid dyes and super milling or fast acid or neutral dyes. The colorfastness of fabric is decided by which of these dyes are used.

- Colorfastness to wet scrubbing is only for pigment printing. Pigment has no affinity to fiber yet it can be applied to all the fibers.  Here a brush is used to see the shade change. 

- Colorfastness to ozone is used only for Denim, which tends to turn yellow either due to atmospheric fumes or ozone. 

- REACH- Registration Evaluation Authorisation of Chemicals is a European document which enlists 800 chemicals which are carcinogenic. Out of which 56 chemicals are SVHC- substances of very high concern. Out of these 56, only 25 are related to textiles. 

- Presence of Alkyl Phenol Ethoxylate is a compound present in cheap detergents. 

- Colorfastness is the property of a color to retain its color under different conditions of use. 

- Colorfastness to washing is checked for many different fibers using a multifiber fabric. It is important to know the colorfastness against different fibers as we don’t know which all fibers will go together in a washing load. Please see Picture Source and Procedure here.

Washing Fastness Tester




- ISO grey scales are used. There are two types of shade cards- color staining and color change ( shade change).  Grey scales are used as opposed to colored scale because only intensity of color change is seen vis-a –vis intensity of grey scale. 

- Internationally a ½ point deviation is acceptable. Normally the evaluation should be done by minimum two people. This is done with D-65 light source for evaluation. 

- This scale is used  for all tests except light fastness ( For light fastness we use 8 scale- Blue wool scales are used)

- Cross staining is transfer of color from a darker to lighter component within the fabric. 

- A case is sited where there was a red dress with white piping. The red dress had a colorfastness of 4-5. But still it was enough to make the white piping pink which was not acceptable. For this case the minimum acceptable fastness was 5. 

- When measuring colorfastness to washing, the test replicates 5 typical home launderings. 

- The Load contains multi fiber test fabric, standard reference detergent, steel balls, washing devices and grade 3 water ( grade 1 is the purest). Addition of steel balls accelates the process. In testing silks steel balls are not used. 


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