Domestic Method of Silk Dyeing with Raw Natural Colours

Abstract

Commercial natural dyes are quite costly as manufacturers are to follow multi-step extraction and purification procedures for standardisation purposes. Upon cost comparison, they lose in the market to synthetic dyes. However, in the handicraft sector, reproducibility may be of lesser importance against cost. In the present study, a domestic method of dyeing silk with the aqueous extract of raw plant/tree components (flower, leave, bark and root) by using a natural mordant and alum will be described. Good dyebath exhaustion and washing and light fastness are observed for some of the natural colouring matters.

Full text

RJTA Vol. 19 No. 3 2015
32
*
Corresponding author:
Tel.: +919433023166
E-mail address: akrc2008@yahoo.in (Asim Kumar Roy Choudhury)
Domestic Method of Silk Dyeing with Raw Natural Colours
Prof. Asim Kumar Roy Choudhury
1*
and Mr. Suman Mitra
2
1*
Govt. College of Engg. and Textile Technology, Serampore
Serampore - 712201, Dt. Hooghly (W.B.), India
2
Birla Century (A Div. of Century Textiles & Ind. Ltd.), Bharuch, Gujarat, India
ABSTRACT
Commercial natural dyes are quite costly as manufacturers are to follow multi-step
extraction and purification procedures for standardisation purposes. Upon cost comparison,
they lose in the market to synthetic dyes. However, in the handicraft sector, reproducibility
may be of lesser importance against cost. In the present study, a domestic method of dyeing
silk with the aqueous extract of raw plant/tree components (flower, leave, bark and root) by
using a natural mordant and alum will be described. Good dyebath exhaustion and washing
and light fastness are observed for some of the natural colouring matters.
Keywords: Natural Colouring Matters, Natural Mordant, Dyeing, Colour Fastness, Silk,
Munsell
1. Introduction
The textile industry has been condemned as one
of the world’s worst offenders in terms of
pollution because of two issues (Business Week,
2005):
1) as many as 2000 different chemicals and a
large number of dyes are used, and many of
them are known to be harmful to human (and
animal) health, and
2) the consumption and subsequently release of
large quantities of water contaminated with a
wide spectrum of processing chemicals as
effluent.
1.1 History of Colourants
Until the end of the 19
th
century, all colouring
materials were obtained from natural sources. The
majority were of vegetable origin; plants, lichen
and trees, although a few were obtained from
insects and molluscs. Over thousands of years, a
large number of natural dyes had been used; it is
significant that only a dozen or so proved to be
practically useful, thus reflecting the instability of
nature’s dyes (Gordon & Gregory, 1987).
In the many past centuries, people learnt various
complicated methods of the application of
colourants to make bright and colour-fast shades.
These include precious “Tyrian purple” or
“Cochineal scarlet” exclusively used by kings and
emperors, madder red by guards and soldiers, and
Brazilwood and logwood by commoners. These
were closely guarded secrets among specific
countries and communities. Textiles were mass
consumption products next to food products. Its
high demand resulted in fierce battles amongst
various countries. At the beginning of the
twentieth century, synthetic dyes were
commercially produced in increasingly larger
quantities. Superior quality and well-defined and
widely-circulated application procedures made
dyeing processes more universal.
1.2 Disadvantages of Natural Colourants
Two hundred years or more ago, the production of
crops such as indigo (and woad), weld and
madder was based on labour-intensive agronomy,
and time-consuming downstream manufacturing
processes for preparing the dye were necessary.
The trade of natural dyes began to decline in the
second half of the 19th century and now 100
years later, many of the dyes that were once
commonplace are little known and difficult to
obtain. Although dyes such as madder, cochineal,
fustic, Brazilwood, sanders-wood, cutch, indigo,
logwood and weld are obtainable, they are
relatively expensive and retailed in small amounts.
What attracts people to textiles coloured with

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33
natural dyes may be one or a combination of
factors, including a preference for naturalness,
environmental friendliness, harmonising natural
shades or just for novelty. In recent years,
considerable research work has been carried out
in various institutes on the standardisation of the
process for the extraction and application of
natural dyes. Efforts are also being made in
simplifying and modifying existing dyeing
techniques to improve the fastness properties,
particularly washing (Roy Choudhury, 2006).
1.3 Revival of Natural Colourants
From the beginning of the 20
th
century, synthetic
dyes with superior properties came into the
market and slowly replaced natural dyes
completely. After a century-long use, we have
realised now that most synthetic dyes are poorly
biodegradable and some are even carcinogenic,
hence they need to be substituted (Roy Choudhury,
2006). On the other hand, natural colours
extracted from vegetables, trees and insects are
eco-friendly and biodegradable. A number of
studies have been made that verify the
eco-friendliness of natural dyes (Sathianarayanan
& Bhat, 2008; 2012; Talreja et al., 2003; Umbreen
et al., 2008).
However, the extraction of dyes from natural
sources is a slow, inefficient, wasteful and very
labour intensive process. Natural colourant
manufacturers follow tedious extraction and
purification procedures and thereby, natural dyes
are marketed at very high prices, which most
dyers cannot afford to purchase.
Natural dyes are generally applied along with
mordants. Mordants are water-soluble and
subsequently fixed or insolubilised by metallic
salts, such as potassium dichromate, copper
sulphate, aluminium salts, etc. Many of these salts
are not eco-friendly.
The present work is an attempt to study the
possibilities of the application of a few freely
available tree/plant components by directly using
domestically available products in small batches.
Most of the colouring matters used are house
waste or can be obtained from very common
types of trees around us. The materials can be
supplied gratis or may be procured at a negligible
cost. The cost advantage against synthetic dyes is
apparent, which are to be procured from dye
manufacturers. One inherent problem of such a
method is poor reproducibility. However, this
problem may be overlooked for silk dyeing which
is mostly done in small batches, particularly in the
handicraft sector.
A cost comparison is not possible because the
colouring matters used in this study are either
waste or collected from locally available trees.
Even if those are to be procured, the cost will be
very low as compared to the cost of synthetic
dyes. Hence, the cost of dyeing in the proposed
process is very low.
With regard to eco-friendliness, the colouring
matters used here are commonly used domestic
materials which are harmless and biodegradable.
In the usual method of dyeing with natural
colourants, various metal salts are used, which are
toxic. However, in the present study, only alum is
used, which is non-toxic. Hence, the proposed
process is completely eco-friendly.
In a similar study (Roy Choudhury et al., 2013),
the authors concluded that silk can be directly
dyed with natural colouring matters without
mordant to obtain wash-fast and light-fast shades.
However, the colour depths are lower. Hence, in
this study, a natural mordant is incorporated.
2. Materials
2.1 Fabric
The specifications of the raw silk fabric used were
picks/cm = 44 ends/cm = 48, G.S.M = 45 & after
degumming, the G.S.M. was 34.
2.2 Natural Colourants Used
Most of the colouring matters used were
household products/waste or obtained from very
common types of trees around us. The drying of
the natural colouring matters was carried out in
open air under shade without any external heating
followed by conditioning in a chamber at a
relative humidity of 65% and temperature of
27
0
C.
The nine types of colourants used in this study
were collected from various parts of trees/plants,
namely:
1) tesu flower (PF),
2) marigold yellow flower (MYF),
3) marigold red flower (MRF),

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34
4) butterfly pea flower (BF),
5) dried tea leaves (TL),
6) eucalyptus bark (EB),
7) jackfruit bark (JB),
8) latkan seeds (LS), and
9) Manjishta root (MR).
The details of the colourants are as follows:
PF  Botanical name: Butea monosperma;
Commercial name: Palas; Butea or Flame of the
Forest is a genus of flowering plants that belong
to the pea family, Fabaceae. Its dried flowers are
used to dye different textiles. It gives yellowish
shades with an acceptable fastness rating.
MYF and MRF ー Commercial name: Genda;
Botanical name: Calendula Officinalis; Marigolds
are hardy, annual plants and great for cheering up
any garden. Marigolds come in different colours,
with yellow and orange being the most common
ones. Most marigolds have a strong, pungent
odour and great value in cosmetic treatments.
BF ー Commercial name: Aparajita; Botanical
name: Clitoria ternatea; The BF is a perennial
herbaceous plant. Its leaves are elliptic and obtuse.
The most striking feature about this plant is its
vivid deep blue flowers (about 4 cm x 3 cm in
size). They are solitary, with light yellow
markings. There are some varieties that yield
white flowers.
TL ー Commercial name: Tea; Botanical name:
Camellia sinensis; As a cultivated evergreen plant,
tea plants are usually trimmed to less than six feet
in height. Their chemical content and flavour are,
however, different due to their respective
fermentation process. Green TL are allowed to
wither in hot air, then pan-fried to halt the
oxidation (fermentation) process. The black TL
used in this study are fermented in cool, humid
rooms, until the entire leaf is darkened (Iziko,
2004).
TL contain many compounds, such as
polysaccharides, volatile oils, vitamins, minerals,
purines, alkaloids (e.g. caffeine) and polyphenols
(tea tannins called catechins and flavonoids)
TL give brown shades with acceptable fastness
ratings. Even exhausted TL after the liquor has
been extracted for drinking contain considerable
colouring matters for use in dyeing.
EB ー Commercial name: Iron Bark; Botanical
name: Eucalyptus globulus labill. Eucalyptus is a
tall evergreen tree. It attains a height of more than
300 feet. The appearance of its bark varies with
the age of the tree. Its bark consists of long fibres
and can be pulled off in long pieces.
JB  ー Commercial names: Jackfruit, Kathal;
Botanical name: Artocarpus heterophyllus; The
jackfruit tree is unique in that it directly produces
large fruits from its stems. The jackfruit tree is
most probably native of the rain-forests of the
Western Ghats. Jackfruits have a strong yellow
colour.
LS  ー Commercial names: Annatto, Latkan;
Botanical name: Bixa Orellana; Latkan trees are
an evergreen shrub or small tree, and 2-8 m in
height. Their fruits are spherical or broadly
elongated ovoid capsules, more or less densely
cloaked with long bristles, green, greenish-brown
or red when matured; and their seeds are
numerous, with a bright orange-red fleshy coat.
‘Bixa’ is derived from a local South American
name.
MR  ー Common Names: Madder, Manjistha,
Majith; Botanical Names: Rubia cardifolia
(Indian madder) Rubia tinctoria (European
madder); Natural Dye: Red, pink and orange
dyestuff for textiles.
Madder is one of the oldest natural dyes. In a way,
indigo and madder are the primary ancient natural
dyes used by humans for dyeing textile
throughout the ages. The cultivation of madder
needs a sub tropical climate and preferably, moist
soil. It is cultivated at the foot of the Himalayas in
large quantities.
2.3 Mordant and Fixing Agents Used
Mordant ー Harda (vernacular name in Hindi);
Botanical name: Terminalia chebula Retz;
Commercial name: Myrobolan; Dye ingredient:
Dried fruit skin after grinding; Natural Dye:
Greenish yellow dyestuff and a natural mordant
for textiles.
Myrobolan is a fruit of the Terminalia chebula
tree. It is used as greenish yellow dyestuff for
textiles, and also as a natural mordant in many
cases. Myrobolan is used as a substitute for tannic
acid.
Fixing agents  ー Potash Alum, K
2
SO4, Al

RJTA Vol. 19 No. 3 2015
35
2
(SO
4
)
3
, 24H
2
O
3. Methods
3.1 Extraction of Natural Colouring Matters
First, 1 litre of deionised water was heated and the
dried chips of a natural colouring matter (20 g/l)
were added into the hot water and stirred with a
glass rod. The liquor was allowed to boil for
25-30 min until the volume was reduced to about
700-800 ml. Then, the solution was filtered by
using an open structured nylon bolting cloth
(usually used for making printing screens) with
50 denier 130 mesh (threads/inch) monofilament
nylon. The volume was adjusted to one litre by
adding deionised water and stirred well with a
glass rod before use (Seri, 2000).
3.2 Preparation of Silk
Raw silk fabric needs to be degummed to remove
unwanted sericin from the fabric before dyeing.
The fabric was first treated by using the following
items and parameters:
washing soap (Sunlight) – 5 g/l,
soda ash – 2 g/l,
temperature – boiling,
pH =10.5,
time – 2 hours, and
M:L ratio – 1:40.
The fabric was further treated by using the above
without soda ash under identical conditions. This
was followed by cold washing and treatment with
5 g/l liquid ammonia at room temperature for 15
min. The fabric was washed cold and dried. The
weight loss due to degumming was about 24.5%
3.3 Dyeing Method
Step 1: Treatment with mordant (myrobolan)
In this step, the fabric was treated with an
extracted solution of myrobolan (extraction
procedure is the same as the dye extraction
procedure).
Myrobolan = 20 g/l
M:L ratio = 1:100
Temperature – 80 ºC
Time – 30 min
Step 2: Treatment with fixing agents in a bath that
contains alum (20 g/l), with the following
parameters:
M:L ratio = 1:100
Temperature – 80 ºC
Time – 30 min
Step 3: Dyeing with the natural colouring matters
under three different dyeing conditions:
a) acidic (AC) (by adding 1% o.w.m. glacial
acetic acid, purity: 99.5%, make: SD Fine
Chemicals Ltd., Mumbai),
b) alkaline (AL) (by adding 1% o.w.m. soda ash,
minimum assay (acidometric): 99.5%, make:
SD Fine Chemicals Ltd., Mumbai), and
c) neutral (N) conditions.
The pH values of the extracts under the three
conditions above are shown in Table 1.
Table 1. pH of the Extract (20 g/l) of Natural
Colouring Matters
Colouring
matter Original
pH pH after addition of
acid alkali
PF 6.6 5.4 7.9
MYF 6.4 5.5 7.8
MRF 6.4 5 7.5
BF 6 5 7
TL 5.8 4.8 7.1
EB 6 5 6.8
JB 6.5 5.3 7.2
LS 6 5 7
MR 7 6 7.8
Dyeing conditions:
Weight of fabric = 1 g.
M:L ratio = 1:100
Dyeing temperature – 85ºC – 90ºC
Dyeing time – 1 hour
3.4 After Treatment
After dyeing, the fabric was washed with cold
water, and Then, soaped with a non-ionic
detergent (Sandozin NITI, alkyl phenol
polyglycol ether, Clariant) (2 g/l) at a temperature
below 60
0
C to increase the rubbing fastness.
Finally, the dyed fabric was washed with cold
water and dried.

RJTA Vol. 19 No. 3 2015
36
4. Measurements
4.1 Measurement of Colour
The % transmittance and absorbency of the dye
solutions were measured by using an X-RITE
Colour i5 spectrophotometer.
The colour measurement of the dyed samples was
carried out by a computer colour matching system
(Color iControl) in terms of CIELAB co-ordinates
L, a
*
, b
*
, and % colour strengths WSUM and
SWL values.
The value of the Munsell parameters, namely, the
Munsell hue, was measured in two ways.
Instrumentally, these were predicted by the
software that was provided with the
spectrophotometer.
Furthermore, the Munsell parameters of the
samples were visually assessed by using the
SCOTDIC colour specifier under a Variolux
colour matching cabinet (D65 lamp) after proper
training.
SCOTDIC (Scotdic Colour Book, Kensaikan Ltd.,
Higashi-ku, Osaka 541 Japan), a textile version of
the Munsell system created by the fusion of two
different systems – the Standard Colour of Textile
(Japan) and Dictionnaire Internationale de la
Couleur (France), is adopted by over 8000
companies worldwide. The standard textile
colours of the SCOTDIC colour system are
widely used as colour tools by fashion colour
professionals. The system has three versions -
glossy (2468 colours on polyester crepe fabric),
matte (2038 colours on cotton poplin fabric) and
yarn (1100 colours on wool yarns). The matte
version is used in this study.
4.2 Fastness Assessment
4.2.1 Washing Fastness
The ISO washing fastness test no. 2 (The Society
of Dyers and Colourists, 1978) of the dyed
samples was carried out by treating the dyed
fabric stitched with adjacent white fabrics at 50°C
(±2.0) for 45 minutes with 5 g/l soap (without
soda) in an AATCC launder-o-meter, followed by
assessing the change of colour and staining by
using the respective grey scales.
4.2.2 Light Fastness
The light fastness of the dyed samples was
assessed by exposing them in a Xenotest 150S
(M/s Atlas) light fastness tester by following the
BS 1006 B02-1078 method.
5. Results and Discussion
5.1 Absorbency of dye solutions
The change in absorbency or optical density (OD)
at λ
max
with change in concentration for various
colouring matters was studied. The extract of the
natural colouring matters was diluted to different
extents and the OD of the dilution was measured
by using a spectrophotometer in the transmission
mode and plotted against the concentration. The
trend line (OD vs. Conc.) was plotted and
considered as the calibration curve for each
colouring matter. The curve was utilised for
determining the concentration of residual
colourant in the exhaust dyebath.
Figure 1 shows the calibration curve of PF, MYF,
MRF, LS, and MR, while Figure 2 shows the
calibration curve for BF, TL, EB, and JB. The
coefficient of correlation (R
2
) values between OD
and concentration of colouring matters are shown
in Table 2. The table shows that the correlations
are very high in all of the cases, and the lowest is
for MYF (0.9437). The high correlation confirms
that the solutions of the colouring matters obey
Beers-Lambert’s law and there is no aggregation
of the colouring matters in the solutions. Only
three points were considered for MYF as at higher
concentrations, the OD is very high versus that of
the others and may cross the range and violate the
Beers-Lambert’s law.
5.2 Dyebath Exhaustion
Figure 3 shows the % exhaustion of the dye bath
for each colouring matter after dyeing under AC,
AL and N conditions which may be summarised
as follows:
1) poor exhaustion (around 15%) – LS;
2) moderate exhaustion (around 30-40%) - PF
and TL; and
3) good exhaustion (around 40-50%) - MYF,
MRF, EB, JB, and MR.

RJTA Vol. 19 No. 3 2015
37
Table 2. Coefficient of Correlation (R
2
) of Optical
Density of the Various Colouring
Solutions
Colouring
Matter
Coefficient of Correlation
of Optical Density vs. Conc.
PF
0.9798
MYF 0.9437
MRF
0.985
BF
0.9981
TL 0.9762
EB
0.9957
JB
0.9978
LS 0.9987
MR
0.9992
Fig. 1. Optical Density vs. Concentration Curve
of PF, MYF, MRF, LS, and MR Extracts
Fig. 2. Optical Density vs. Concentration Curve
of BF, TL, EB, and JB Extracts
The exhaustion also depends on the pH of the dye
bath. The highest exhaustion under AC conditions
was obtained by using MRF and MR. So, they
behave like acid dyes. The highest exhaustion
under N conditions was obtained by using MYF
and JB; so, they behave like direct dyes. The
highest exhaustion under AL conditions was
obtained through the use of PF and EB. This may
be linked to their higher solubility in the presence
of alkali. The colour of the dyebath also changed
to varying extents after dyeing due to the changed
pH and also the addition of alum. The change was
considerable in the case of BF and hence, the
concentration of the residual dye bath of BF could
not be measured.
5.3 Colour Strength WSUM (%)
The colour strength value is a single numerical
value related to the amount of colour absorbing
material (colourant) contained in a specimen. The
colour strength value of specimens measured on a
spectrometer most often involves the calculation
of the Kubelka-Munk function (K/S value) at one
or more wavelength intervals. A commonly used
equation for the calculation of the K/S value for
opaque specimens (i.e. textiles) at a specified
wavelength (λ) is:
where K = coefficient of absorption
S = coefficient of scattering
R
λ
= reflectance at wavelength λ
WSUM denotes the K/S value weighted by a
visual function (such as
λ
x
,
λ
y
,
λ
z
functions
under the D65 illuminant) and averaged over a
wavelength interval within the visible spectrum,
then divided by the number of wavelength
intervals averaged.
WSUM = ( Σ
λ
[(K/S
λ
×
λ
x
* E
λ
) + (K/S
λ
×
λ
y
×
E
λ
) + (K/S
λ
×
λ
z
× E
λ
)])/n (2)
E = Relative spectral power distribution of the
illuminant (normally D65)
λ
x
,
λ
y
,
λ
z
= tristimulus weighing values for
selected observer (normally 10
0
)
n = number of wavelength intervals used.
)1(
2)1(
2
λ
λ
λ
R
R
S
K−
=







RJTA Vol. 19 No. 3 2015
38
% strength WSUM =
(Colour Strength WSUM
sample
/Colour Strength
WSUM
standard
) × 100.
i.e. the relative difference in colour strength
between the standard and a sample (AATCC,
1996).
Figure 4 shows the colour strength (WSUM) of
various colouring matters under N and AL
conditions by considering the colour strength of
the sample dyed under AC conditions (standard)
as 100%. The figure shows that the colour
strength of the dyed sample under N and AL
conditions in many cases is higher than the colour
strength of the respective sample dyed under AC
conditions. The colour strength under N
conditions is higher (than that under AC
conditions) in the cases of PF, BF, TL and JB.
This means that these colouring matters may
probably behave like direct dyes. MYF, MRF, LS
and MR show higher colour strength in AC
conditions, thus indicating that they behave like
acid dyes.
On the other hand, the colour strength under AL
conditions is higher in the cases of PF, JB and LS
than that under N conditions, which may be due
to the higher solubility of alkali.
Under AL conditions, less than 90% colour
strength is observed in the cases of MYF, MRF
and MR. Under N conditions, only MYF shows
less than 90% of the exhaustion under AC
conditions.
Fig. 3. Dyebath Exhaustion (%) of Natural
Colouring Matters under Three
Different Dyeing Conditions
Fig. 4. Colour Strength (WSUM) of Silk Dyed
with Natural Colouring Matters under
Acidic Conditions (AC) as Standard.
5.4 Colour Value (Strength) SWL
The Colour Value SWL is calculated at a single
wavelength (usually at λ
max
).
(Colour Value)
swl
=
λ






S
K
(3)
where
λ
is the wavelength over the available range
of the spectrophotometer.
Figure 5 shows the Colour Value (strength) SWL
of various colouring matters under N and AL
conditions by considering the colour strength of
the sample dyed under AC conditions as 100%.
The average trends of the colour strength under
AC, N and AL conditions are very similar to those
in the case of Colour Strength WSUM. There are
only one or two cases where the predicted Colour
Strength SWL was different from that of WSUM.
For example, dyeing with PF under N conditions
showed lower Colour Strength SWL than that
under AC conditions, while the colour strength
predicted was higher in the case of Colour
Strength WSUM.
Fig. 5. Colour Strength (SWL) of Silk Dyed with
Natural Colouring Matters under Acidic
Conditions (AC) as Standard.

RJTA Vol. 19 No. 3 2015
39
Fig. 6. CIE Lightness Values of Silk Dyed with
Various Colouring Matters
5.5 Lightness
Figure 6 shows the CIE lightness of silk dyed
with various colouring matters under AC, N and
AL conditions. The figure shows that for all
colouring matters, the lightness values are more
or less similar when dyed under AC, N and AL
conditions.
On the basis of lightness (L*), the dyed samples
may be classified into three groups, as those with:
Fig. 7. CIE a*-b* Diagram of Silk Dyed with PF,
MYF, MRF, BF an d TL.
Fig. 8. CIE a*-b* Diagram of Silk Dyed with EB,
JB, and LS.
• High lightness (around 60): PF,EB, JB
and LS (lighter shades);
• Moderate lightness (around 55): MRF and
BF (moderate shades); and
• Poor lightness (around 45): MYF, TL and
MR (darker shades).
5.6 a*-b* diagram
Figure 7 shows the a*-b* diagram (CIELAB) of
PF, MYF, MRF, BF and TL under the 3 dyeing
conditions.
• With the use of PF and TL, the silk samples
dyed under AC, N and AL conditions are
very similar in colour as indicated by their
close locations in the a*-b* diagram.
Fig. 9. CIE a*-b* Diagram of Silk Dyed with MR
under Three Different Dyeing Conditions

RJTA Vol. 19 No. 3 2015
40
Fig. 10. Colour Difference (CMC 2:1) of Silk
Dyed withDifferent Natural Colouring
Matters under Acidic Conditions (AC)
as Standard
• Silk dyed under AL conditions with MRF (i.e.
MRF-AL) and samples dyed under AC
conditions with MYF (i.e. MYF-AC) are
quite different in colour than the other
corresponding dyed samples. Among these
four colouring matters, TL shows the most
red and MRF shows the most yellow versus
the other two, i.e. PF and MYF have
intermediate shades.
Figure 8 shows the a*-b* diagram (CIELAB) of
samples dyed with EB, JB, and LS colouring
matters. They are very close to each other in the
a*-b* diagram thus showing similar hue and
chroma values. The chroma values are quite low
as indicated by the low a* value (<4).
Figure 9 shows the a*-b* diagram (CIELAB) of
samples dyed with MR under AC, N and AL
conditions. The very high a* and b* values
(around 30) indicate the high chroma values of
these samples.
5. 7 Colour Difference
Figures 10 and 11 shows the colour differences of
silk dyed under N and AL conditions in terms of
∆E (CMC) and ∆E (CMC) respectively by
considering silk dyed under AC conditions as the
standard. The colour difference values are much
higher on the CIELAB scale versus the values on
the CMC scale. The ∆E (CMC) values range from
0.17 to 1.9 while ∆E (CIELAB) range from 0.32
to 4.1. Except for a few cases, ∆E (CIELAB) is
around double the respective ∆E (CMC) values.
Fig. 11. Colour Difference (CIELAB) of Silk
Dyed with Different Natural Colouring
Matters under Acidic Condition s(AC)
as Standard.
Fig. 12. Instrumental and Visual Munsell Values
of Silk Dyed with PF, MYF, MRF and
BF
• The colour differences under three different
pH conditions are very close (within 1 ∆E
(CMC) unit and 2 ∆E (CIELAB) units) in the
cases of PF, EB, JB and LS.
• The colour differences of the samples dyed
under N and AL conditions are quite high
against the samples dyed under AC
conditions in the cases of MYF, MRF, and
BF.
• The samples dyed under N and AL
conditions are quite close in colour (less
colour difference) in the cases of PF, MYF,
BF and LS.
• The colour of the samples dyed under N and
AC conditions is quite close while respective
samples dyed under AL conditions are quite
different in the cases of MRF, TL, EB and
MR.

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41
Fig. 13. Instrumental and Visual Munsell Values
of Silk Dyed with TL, EB, JB, LS and
MR.
Fig. 14. Instrumental and Visual Munsell Chroma
of Silk Dyed with PF, MYF, MRF and
BF
5.8 Visual Colour Parameters
The instrumental colour attributes (L*, a*, b*)
can not express colours in terms of visual colour
perception. In the Munsell colour order systems,
any colour is represented by three parameters;
namely, hue, value and chroma. While hue
represents the colour of the sample, value
represent lightness and chroma represents the
saturation of colour.
In the present study, the Munsell parameters re
both visually and instrumentally measured. In the
visual system, the colour of the dyed samples is
assessed by using the Scotdic colour atlas.
SCOTDIC, a textile version of the Munsell
system created by the fusion of two different
systems – the Standard Colour of Textile (Japan)
and Dictionnaire Internationale de la Couleur
(France), is adopted by over 8000 companies
worldwide. The instrumental Munsell parameters
were obtained from a spectrophotometer.
Fig. 15. Instrumental and Visual Munsell Chroma
of Silk dyed with TL, EB, JB, LS and
MR
Fig. 16. Washing Fastness Ratings of Silk Dyed
with Natural Colouring Matters under
Three pH Conditions
Table 3 shows the Munsell hues of the dyed
samples measured by both instrumental and visual
methods. As these are alpha-numerical values,
graphical representations are not possible. All
the dyed samples belong to the Y and YR hue
groups. The respective instrumental and visual
hues for all of the dyed samples are very close. In
the case of MYF, the instrumental hues belong to
the Y hue group while visual hues belong to the
YR hue group. However, if we consider the prefix
number to the hue name, they are very close to
each other in the hue circle. The same is the case
for the colouring matter MR.
Figures 12 shows a comparison of the
instrumental and visual Munsell values for PF,
MYF, MRF and BF used under AC, N and AL
conditions while Figure 13 shows that for TL, EB,
JB, LS and MR.

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42
Table 3. Munsell Hue of the Dyed Samples
Colouring
Matter
Dyeing
Condition
Instrumental
Visual
PF AC 3.1Y 2.5Y
N
3Y
2.5Y
AL
3Y
2.5Y
MYF AC 1.1Y 10YR
N
1.2Y
10YR
AL
1.1Y
10YR
MRF AC 4.9Y 5Y
N
5Y
5Y
AL
4.9Y
5Y
BF AC 9.1Y 7.5Y
N
8.3Y
7.5Y
AL
8.5Y
7.5Y
TL AC 9.5YR 10YR
N
9.4YR
10YR
AL
10YR
10YR
EB AC 2Y 2.5Y
N
3.1Y
2.5Y
AL
3.2Y
2.5Y
JB AC 3.8Y 5Y
N
3.6Y
5Y
AL
3.7Y
5Y
LS AC 4Y 5Y
N
4Y
5Y
AL
4.1Y
5Y
MR AC 9.3R 1.25YR
N
9.1R
1.25YR
AL
9R
1.25YR
Both figures show that the Munsell values
measured instrumentally and visually are very
close to each other. The instrumental values are
little higher in all cases, except for MYF and MR
than the respective visual values. The Munsell
values of PF, EB, JB and LS are high (around 6)
and those of MYF and MR are low (less than 5)
thus indicating lighter and darker shades
respectively. The other colouring matters (MRF,
BF and TL) have intermediate Munsell values.
The Munsell values of silk dyed under AC, N and
AL conditions are more or less similar for all of
the colouring matters.
Figures 14 and 15 show a comparison of the
instrumental and visual Munsell chroma of silk
dyed with the natural colouring matters under AC,
N and AL conditions.
Figure 14 shows the data for PF, MYF, MRF and
BF, while Figure 15 shows the data for TL, EB,
JB, LS and MR. Instrumentally measured values
are about 1 or 2 units lower than those of the
visually assessed Munsell chroma, except for
MYF (higher) , TL (equal) and JB (very close). It
is important to note that chroma values for
samples dyed under AC conditions are either
equal or even lower in a few cases. Silk samples
dyed under N and AL conditions have more or
less similar chroma. The figures show that silk
fabrics dyed with MR under all three pH
conditions have visually measured chroma of 10
followed by PF (around 7), MYF (around 6) and
EB (around 6). The others have poorer chroma,
and BF has the poorest chroma.
5.9 Washing Fastness
Figure 16 shows wash fastness ratings of the dyed
samples. Washing fastness ratings are good (4-4.5)
in the cases of BF, EB and LS. MR has
comparatively, the poorest washing fastness. For
other colouring matters, the fastness ratings are
moderate. For most of the colourants, the
washing fastness ratings are the same for samples
dyed under AC, N and AL conditions.
All of the natural colouring matters used in this
study are practically non-staining on cotton
(mostly 4-4.5), silk (4.5-5), wool (mostly 5) and
viscose (mostly 5). Minimal staining was
observed with PF while dyeing under AC and AL
conditions.
5.10 Light Fastness
Figure 17 shows the light fastness of the dyed
samples tested in the Xenotest 150S. The light
fastness ratings are acceptable when PF, EB, JB,
LS (around 4) are used and the highest rating
obtained by the use of MR (5). The light fastness
is moderate in the cases of BF and TL (around 3
and less). The light fastness is very poor (1) in the
cases of both types of marigold flowers – MYF
and MRF.

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43
Fig. 17. Light Fastness Ratings of Silk Dyed with Natural Colouring Matters under Three Different Dyeing
Conditions
6. Conclusion
Silk fabric is dyed with nine natural colouring
matters; namely, PF, MYF, MRF, BF, TL, EB, JB,
LS, and MR in the raw form.
Good dyebath exhaustion is observed with the use
of MYF, MRF, EB, JB and MR.
In the cases of PF, BF, TL, and JB, the colour
strengths are higher under N conditions than the
respective colour strengths under AC conditions.
This means that these colouring matters probably
behave like direct dyes. MYF, MRF, LS and MR
show higher colour strength in AC conditions,
thus indicating that they behave like acid dyes.
Moderate CIELAB lightness (L*) values of silk
dyed with MRF and BF indicate that they possess
moderate depths of shade while silk dyed with
MYF, TL and MR are darker.
The a*-b* diagrams (CIELAB) of PF, MYF, MRF
and TL show that TL provides the most red, MYF
the most yellow, while PF and MRF give
intermediate hues. EB, JB and LS provide very
similar colours, but have poor Munsell chroma.
MR provides a very bright colour and gives high
chroma values.
The very low colour differences in the cases of PF,
EB, JB and LS used under AC, N & AL
conditions indicate that they are identical in
colour, while with the use of MYF, MRF and BF,
the samples dyed under AC conditions are very
different than those dyed under N and AL
conditions.
The Munsell hue shows that most of the shade
belongs to the Y and YR Munsell hue groups.
Only few have the Munsell ‘R’ hue. The hues
measured by visual and instrumental methods are
very close. Silk dyed with PF, MYF, MRF and
MR have Munsell chroma values above 6.
The washing fastness (ISO W. Test No. 2) is good
(rating 4) in the cases of BF, EB and LS. For other
colouring matters, except for MR, the rating is
moderate (3). No staining during washing can be
observed on any type of textile fibre.
The light fastness is good for silk dyed with PF,
EB, JF, LS and MR (rating 4-5) and moderate (3)
in the cases of BF and TL. It is very poor (1) in
the cases of MYF and MRF.
So it may be concluded that except for the
marigold flowers, other colouring matters can be
used to obtain yellow and reddish yellow shades
on silk. In considering the very low cost of the
colouring matters used, these eco-friendly means
of dyeing silk can be utilized.
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44
Textile Industry’, June 5,
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