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. 

Now that you've finished reading this post, what are you going to do? You should join the Forum.

Some Selected Notes on Textiles - Part 1

- Strength of Cotton is in between silk and wool. Silk is the strongest fiber.

-  Cotton is less elastic than Silk.

- Cotton wrinkles as the cellulose from which it is made has hydrogen bonds that break when washed due to agitation or mechanical action. They are formed again when ironed but in different places. Read more...

- Perspiration is of two types- Alkaline and acidic. Majority of the perspiration is alkaline. Cotton is not affected by alkaline perspiration whereas silk does.

- Coloration principle involves physical absorption of water soluble dyes, transferring of dye on to fiber, dye becoming water soluble and is retained inside the fiber.

- Reactive dyes physically react with fibers and form covalent bonds. The process involves two steps: 1. Dyeing with the dye in presence of salt to effect as exhaustion as possible ( transferring of dye from solution to fabric) and 2. Chemically reacting the dye with water in presence of alkali like soda ash.

- Reactive dyes also react with the water in which they are dissolved.  This is called hydrolysis of dyes. These hydrolysed dye has to be removed from the fiber by proper soaping else color fastness will be a major issue.

- Disadvantage of reactive dyes are that the hydrolysis accompanies fixation, as told earlier. Also there there is approximately 30% wastage of dye due to hydrolysis. Only 70% of the dye react with fiber.  To remove hydrolysed dyes there is an excessive consumption of water. Also colored effluent discharge is a major problem. It also involves large amount of electrolyte ( Common salt) as a exhaustive agent. It is also costlier. 

Now that you've finished reading this post, what are you going to do? You should join the Forum.

Thanks for Your Submission !!

Toda Embroidery- A Tango of Needles

Toda Embroidery

 

Toda people have a unique way of dressing. Both men and women cover themselves with a unique shawl  called Puthukuli which is designed and embroidered by themselves. It is intricately embroidered with red and blue or black threads at the borders. It is worn like a Roman Toga.  On one end of the cloth three stripes- two of red and one of black are woven into it. It is in these stripes that the embroidery is worked.  The darning stitch is used for embroidering motifs and patterns.  The base fabric is  bleached white cotton with a balanced weave structure. It enables the artisan to count and embroider the pattern.  No embroidery  frame is used  but instead they use their fingers to see, count and pick up threads by stretching the fabric. At each turn little tufts of threads are left protruding body. This technique ensures that each pattern created has a rich texture.  Patterns used for embroidery are similar to the ones used for tattoo marks.

Sources of Images and Text

1. http://www.cohands.in/handmadepages/pdf/331.pdf

2. http://www.parikramaholidays.com/pdf/Poothukuly-A-Toda-Ceremonial-Shawl.pdf

3.  A very nice story for children depicting Toda Culture http://www.arvindguptatoys.com/arvindgupta/22nbt-%20The%20Toda%20&%20The%20Tahr%20by%20E.R.C.%20Davidar.pdf