netural dye

1. PRAVEESH KUMAR
Nitra technical campus
TC – 3rd Year

2.  Natural dyes can be defind as those colours
which are extracted from a combination of
vegetable, mineral and insect sources.
 Natural dyes are obtained from plant
sources, viz flowers , leaves, barks, seeds,
roots etc.
 There are as many as 500 plant species
identified as source of dyes.

3.  Natural dyes are simply dye substances
extracted from natural sources.
 Although the main source of dyes for early
times, they have largely been replaced by
synthetic dyes, which are usually more reliable,
cheaper and can be supplied more readily.
 The word ‘natural dye’ covers all the dyes
derived from the natural sources like plants,
animal and minerals.
 Natural dyes are mostly non-substantive and
must be applied on textiles by the help of
mordants, usually a metallic salt, having an
affinity for both the colouring matter and the
fibre.

4.  Due to their non toxic properties, less side
effects, more medicinal values, natural dye
used in day to day food products and in
pharmaceutical industry.
 Dyes obtained from natural sources are free
from chemicals and they do not have a bad
effect on the skin of the wearer .
 It is the need of the day to exploit the forest
wealth which can provide us with the
significant sources of imparting beautiful
dyes.

5.  These metallic mordant’s after combining
with dye in the fibre it forms an insoluble
precipitate or lake and thus both dye and
mordant get fixed to become wash fast to a
reasonable level.

6.  Natural coloring matters are broadly classified
in three categories.
 Vegetable origin:- Colorants derived from
root, leaf, bark, trunk, fruit and flowers of
plants.

7. Animal origin:
Lac, Cochineal and kermes have been the
principal dye yielding insects.

8. Mineral origin:
Various inorganic metal salts and metal oxides

9.  There are primarily four sources from which
natural dyes are
 Specialised plant and animal sources: Many
plants and some animals have been
identified as potentially rich in natural dye
contents, and some of them have been used
for natural dyeing for quite some time.
 Various parts of plants like roots, stems,
barks, leaves, fruits and seeds may contain
colouring matter.

10.  Normally natural dyes are extracted from
the roots, stems, leaves, flowers, fruits of
various plants, dried bodies of certain insects
and minerals.
Some plants may have more than one
colour depending upon which part of the
plant one uses.
 The shade of the colour a plant produces
will vary according to time of the year the
plant is picked, how it was grown, soil
conditions, etc. The minerals in the water
used in a dye bath can also alter the colour.
Some natural dyes contain natural mordants.

11.  Few natural dyes are colour-fast with fibres.
Mordants are substances which are used to
fix a dye to the fibres. They also improve the
take-up quality of the fabric and help
improve colour and light-fastness. The term
is derived from the Latin mordere, to bite.
 Some natural dyes, indigo for example, will
fix without the aid of a mordant; these dyes
are known as ‘substantive dyes’. Others
dyes, such as madder and weld, have a
limited fastness and the colour will fade with
washing and exposure to light.

12.  Mordants are substance used to fix the
natural dyes to natural fibres- protein or
animal based like wool and silk and cellulose
or plant based like cotton. Mordants can also
affect the resulting colour the fibre will take
from the natural dye. For the purpose of the
test three mordants are used i.e. copper
sulphate, ferrous sulphate and aluminium
potassium sulphate.

13.  Mordants and dyes may be applied in three
ways.
 Pre-mordanting where the mordant is applied
first, followed by dyeing.
 Post-mordanting where the dyeing is done
first and then mordanting is carried out.
 Simultaneous mordanting where the mordant
and dye are mixed together and are applied.

14.  Selection of medium for the extraction of
dye:-
 To select best media of extraction of dye,
following three medium for extraction were
studied:
 Acidic Medium
 Alkaline Medium
 Aqueous Medium

15.  Alkaline Medium: - Alkaline medium was
prepared by adding sodium carbonate by
maintaining the pH 8to 10 in 100ml of distilled
water.
 10g of dye stuff was added in a beaker and it
was made to boil at 80oC for 60 min. The
solution was filtered and then it was oven dried
until the solution turns into powder. Accurate
amount of distilled water was added and again
pH is checked, if the pH is 8 to 10 then dyeing is
carried out for 1hour at 600C. Then the samples
were allowed to cool at room temperature then
it was taken out, rinsed in water and dried in
shade.

16.  Acidic Medium :- Acidic Medium was
prepared by adding few drops of acetic acid
in 100ml of distilled water by maintaining
the pH 4 to 5. 10g of dye stuff was added in
a beaker and it was made to boil at 80oC for
60 min. The solution was filtered and then it
was oven dried until the solution turns into
powder. Accurate amount of distilled water
was added and again pH is checked, if the pH
is 4-5 then dyeing is carried out for 1hour at
600C. Then the samples were allowed to cool
at room temperature then it was taken out,
rinsed in water and dried in shade.

17.  Aqueous Medium:- Aqueous Medium was
prepared by adding 10g of dyestuff in 100ml in
water by maintaining the pH from 6 to 5 without
using any chemicals. 10g of dye stuff was added
in a beaker and it was made to boil at 80oC for
60 min. The solution was filtered and then it was
oven dried until the solution turns into powder.
Accurate amount of distilled water was added
and again pH is checked, if the pH is 6 to5 then
dyeing is carried out for 1hour at 600C. Then the
samples were allowed to cool at room
temperature then it was taken out, rinsed in
water and dried in shade.

18. Fibre content determines the type of dye required
for a fabric:
Cellulose fibres: cotton, linen, hemp, ramie,
bamboo, rayon
Protein fibres: wool, angora, mohair, cashmere, silk,
soy, leather, suede

19. • They are obtained from
renewable sources.
• Natural dyes are cost effective
• Natural dyes cause no disposal
problems

20. • It is time consuming to extract
from the raw materials.
• Availability of the natural dyes
are limited.
• Synthetic fibers, which are
becoming widely popular can not
be dyed with natural dyes.

21.  Natural dyes are known for their use in coloring of food
substrate , leather as well as natural protein fiber like
wool and silk and cotton as a major areas of application
from pre-historic times.
 Non-toxic and non-allergic effects of natural dyes instead
of synthetic dyes.
 These are biodegradable
 Natural dyes produce very soothing and soft shades as
compared to synthetic dyes
 However, natural dyes are expensive