Dyeing of textiles
Practical Action
The choice of mordant for a particular plant is
dependant upon the material with which it will
be used. It is necessary to check a recipe before
using a plant, or one can experiment to see what
effect a mordant has for a particular application.
It is recommended that plants be grown
specifically for the purpose of dyeing. Harvesting
plants from the wild on a non-sustainable basis
can endanger the survival of the plant. Many
lichens are registered as protected organisms and
it is illegal to gather them from the wild. One
source of lichen is from timber mills where
logged trees are being processed, but ask first!
Figure 3: Groundnuts
Testing dyes
It is always useful and interesting to test the dye which is to be used on a sample of the
yarn or fabric to be dyed. The outcome will depend on the fabric, the mordant that has
been used and dye that has have been chosen. Testing is best carried out on a series of
marked (for identification) samples, which have been mordanted with a number of different
mordants. Tests can be carried out for light, water and washing fastness using simple
standard test methods. Box 1 shows a simple test for washing fastness. Similar tests exist
for water and light fastness (and are given in detail in the same book).
Box 1
Test method for fastness to washing
To test for fastness follow these steps:
1. Take two pieces of fabric about 5cm by 5cm, one of which is undyed cotton and the other
undyed wool. Stitch them together along one side.
2. Take some sample strips of the dyed yarn and spread them evenly between the two pieces
of cloth so that they overlap both sides. If dyed fibre is being tested a combed sample
can be used in place of the yarn.
3. Sew around all four sides of the cloth so that the yarn is held in place.
4. Prepare a similar specimen with dyed materials that has satisfactory properties and place
them in two jars with screw lids containing a solution of 5gm per litre soap or detergent
solution at 30oC.
5. Agitate the two jars gently for 30mins, then remove the fabrics and wash them gently in
clean water for 5mins. Open the stitching and separate the pieces to dry in air.
Examination:
6. Place the dyed yarn next to a sample of the same material which has not been tested,
and compare the change which has taken place. Compare also with the control sample
with satisfactory properties. If the dyeing being tested shows equal or less change than
the satisfactory sample, then it is as good as the satisfactory sample.
7. Place the wool and cotton cloths next to samples of the same material which have not
been tested and compare them with the cloths that have been tested with a satisfactory
dyeing. Equal or less staining shows equal or better fastness.
Source: Dyeing and printing: a handbook, ITDG Publishing
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