Natural dyes – the eco friendly alternative !

Natural dyes – the eco friendly alternative !

Colours by Nature

Colours by Nature

Nature  celebrates  with  colours  and  these  celebrations  are  a  visual  treat. The  living  world  bursts  in  to  a  colourful  expression, especially  around  the  onset  of  spring  (वसंत ऋतू  )  Even  non  living  forms  seem  to  join  the  celebrations  with  their  myriad  hues. And  these  colours  have  always  fascinated  mankind  right  through  the  ages. No  wonder  then  that  Man  has  tried  to  bring  colours  in  to  his  life.

TheUntamedEarth  brings  you this  article  which  talks  about  man’s  tryst  with  colours  and  its  beginning  with  natural  dyes. It  also  explores  the  relevance of  natural  dyes   today.

TheUntamedEarth  thanks  Dr  Sujata  Saxena  of  ICAR – CIRCOT  for  this  wonderfully  informative  article.

TheUntamedEarth

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Natural dyes  –  the eco friendly alternative !

Introduction

Dyes  are  colored  substances  which  enhance  the  aesthetic  value  of  a   substance  by imparting  them  a  reasonably  permanent  colour. In  olden  days  they  used  be  derived from  natural  sources  like  plants, animals  or  minerals  with  plant  parts  such  as  leaves, stem, bark, roots  and  flowers  being  the  main  source. Human  association  with  colours  dates back  to  prehistoric  times. The  myriad  colours  of  nature  have  inspired  man  through the  ages  to  recreate  those  in  the  garments  and  other  items  of  usage,  by  harnessing locally  available  materials. Remnants  of  coloured  cotton  or  flax  textiles  have  been found  at  the  archeological  excavations  sites  of  almost  all  ancient  civilizations  such  as  India, Egypt, Greek, Aztec  and  others  in  spite  of  the  degradable  nature  of  the natural  fibre  textiles. Fragments  of  the  red  coloured   cotton  cloth  dating  back  to around  3000  B.C. were  found  in  the  excavations  at  Mohenjo – Daro,  a  site  of  Indus valley  civilization. As  the  civilizations  developed,  the  art  of  colouration  of  textiles  from  the  dye  bearing materials  also  progressed. In  India, the  craft  of  dyeing  and  printing  of  textiles developed  to  a  great  extent  and  contributed  significantly  to  the  its  wealth. Indian  Calicos  or  printed  cottons  were  extremely  popular  in  Europe  in  17th  and  18th centuries;  they  had  such  a  disastrous  effect  on  domestic  textile  production  in England  that  their  import  was  banned  by  English  parliament  in  1721 A.D. Many villages  in  India  were  specially  set  or  wholly  utilized  only  for  catering  to  the  huge export  demand.

India  is  believed  to  be  the  oldest  centre  for  cultivation  and  use  of indigo  dye  from  where  it  was  introduced  to  Roman  and  Greeks. Other  than  indigo, plants  such  as  madder, aal,  pomegranate,  safflower,  turmeric etc.  were  cultivated  for dyes. Besides, there  were  many  other  trees  as  well  as  creepers, shrubs  and  small herbs  yielding  dyes  and  auxiliaries  which  were  collected  from  the  forests  for  use  in dyeing.

Synthetic  dyes  however  are  of  petroleum  origin  and  therefore  difficult  to  biodegrade. Only  a  part  of  these  gets  fixed  onto  the  fabrics  during  dyeing. The  rest  remains  in the  dyebath  and  along  with  other  dyeing  auxiliaries  and  chemicals  gets  discharged  as  effluent  making  it  highly  coloured  and  polluting. Effluent  treatment  process followed  by  most  of  the  industries  is  not  able  to  degrade  the  dyes  and  these  are merely  separated  as  solid  colored  sludge  requiring  further  disposal. Natural  dyes  on the  other  hand  are  of  biological  origin  and  hence  are  easily  biodegradable  and  do not  give  rise  to  such  problems.

The  environmental  awareness  about  the  pollution  caused  by  the  use  of  synthetic dyes  has  resulted  in  a  global  revival  of  interest  in  natural  dyes  since  the  last decades  of  20th  century.  The  ban  on  certain  azo dyes  synthesized  from  suspected  carcinogens  by Germany  and  other  EU countries  in  1995, has  further  boosted  this interest. A  niche  market  for  textiles  dyed  with  natural  dyes  is  thus  created   due  to  the  demand  from  environment  conscious  consumers  and  it  has  led  to  a  rediscovery  of  natural  dyes. As  the  bulk  of  traditional  knowledge  which  was  passed  down  from father  to  son  and  from  the  master  craftsman  to  the  apprentice  was  lost  due  to  the years  of  neglect, attempts  were  made  all  over  the  world  to  reconstruct  the  dye extraction  and  application  processes  by  interacting  with  a  few  surviving  practitioners of  this  art  in  remote  villages  and  scanning  whatever  old  records  of  this  practice were  available. It  led  to  the  publication  of  a  number  of  books  and  articles  about  the various  natural  dye  sources  and  their  application  processes. Many  natural  dyes  if applied  properly, can  match  the  colourfastness  properties  of  good  synthetic  dyes.

Textiles  dyed  with  natural  dyes  have  their  own  beauty  as  the  colours  are  soft  and earthy, though  the  colour  range  is  rather  limited.

Plant  Extract  Dyed  UV  Protective  Garment

Plant Extract Dyed UV Protective Garment   

Manjistha   Dyed   Polyester  Cotton   Fabric

Manjistha Dyed Polyester Cotton Fabric

Organic  Cotton  Terry  Towel  Dyed  With  Natural  Dye.

Organic Cotton Terry Towel Dyed With Natural Dye.

Sources  of  natural  dyes …

Natural  dyes  unlike  synthetic  dyes  are  not  available  in  ready  to  use  form. These  are obtained  from  natural  materials  and  based  on  their  source  of  origin  are  broadly classified  as  plant, animal, mineral  and  microbial  dyes, though  plants  are  the  major source  of  natural  dyes.

Plant  origin  dyes …

In  natural  dyes, out  of  the  three  primary  colours- blue, yellow  and  red,  blue  is almost  always  obtained  from  indigo  while  there  are  various  sources  for  red  and  yellow  dyes. Some  of  the  important  dye  sources  derived  from  plant  parts  like  leaves, wood, bark, stem, roots  and  flowers  etc. are  listed  below.

Blue dye (indigo) – Leaves  of  the  plants  from  the  Indigofera  genus like I. tinctoria,   I. errecta, I. sumatrana  are  the  best  source  of  this  dye. This  very  important  dye popularly  known  as  the ‘king  of  natural  dyes’  has  been  in  use  from  the  ancient  times  to  the  present  day, for  producing  blue  color. Today  it  is  the  most  popular  dye for  denim  fabrics  though  most  of  it  is  synthetic. Both  are  chemically similar – the chemical  being  known  as   indigotin - but  the  colour  of  natural  indigo  appears  richer due  to  the  presence  of  the  small  amounts  of  a  red  dye  indirubin.  Apart  from Indigofera  species, there  are  several  plants  which  can  be  used  to  produce  indigo  dye. Woad  was  the  natural  indigo  producing  plant  in  Europe. Dyers  knotweed (Polygonum tinctorium), Pala  Indigo (Wrightia tinctoria) and  Khum (Strobillanthes flaccidifolius) are  some  other  plants  traditionally  used  to  produce  indigo.

Red  dyes - Main  plant  sources  are  madder – European madder (Rubia tinctorum- roots) and Indian madder – manjishtha  or manjith (Rubia cordifolia – roots and stem), aal (Morinda citrifolia – roots and bark), safflower (Carthamus tinctorius – florets), Sappan wood  or  patang (Caesalpina sappan) / Brazilwood (Caesalpinia echinata),  ratanjot (Onosma echioides – roots and bark).

Yellow  dyes - Turmeric (Curcuma longa- rhizome), saffron (Crocus sativus – dried stigma of flowers), annatto (Bixa orellana – seeds), Barberry (Berberis aristata - roots, barks and stems), Flame  of  the  Forest, tesu or Palas (Butea monosperma – flowers), pomegranate (Punica granatum - rinds), Myrobolon (Terminalia chebula – fruits  and leaf  galls), marigold (Tagetus sp.), onion (Allium cepa – outer skins), dolu  or  Indian rhubarb (Rheum emodi - roots and rhizome), Kamala (Mallotus phillipensis – fruits) etc.

Brown  dyes - Catechu  or  cutch  obtained  from  the  heartwood  of  Acacia  catechu  dyes cotton, wool  and  silk  to  brown  color.

Manjistha  for  Reds

Manjistha for Reds

 Shades  from  Marigold

Shades from Marigold

Animal  origin  dyes …

Tyrian  purple  from  the  Murex  mollusc  found  in  Mediterranean  sea  was  a  prized natural  dye  in  ancient  days  due  to  its  brilliant  purple  shade  and  very  good  fastness  properties. It  was  highly  expensive, as  thousands  of  molluscs  were  needed  to  get  a gram  of  the  dye  and  hence  was  reserved  for  the  use  of  the  royalty.  Most  of  the other  animal  dyes  are  derived  from  insects  and  yield  red  colour, for  example  lac, which  is  the  hardened  secretion  (stick lac)  of  the  insect  Kerria  lacca, cochineal obtained  from  the  bodies  of  female  insect  Dactylopius  coccus, Kermes  from  the insect  Kermes  licis  also  produces  crimson red colour.

Mineral  origin  dyes …

Some  mineral  pigments  found  in  nature  such  as  cinnabar, red  ochre, yellow  ochre, raw  sienna, malachite, ultramarine blue, azurite, gypsum, talc, charcoal  black etc. have been  used  for  coloration  purposes. Apart  from  the  red  ochre  which  was  used  by  the monks  for  coloration  of  their  robes, these  were  mainly  used  in  paintings  and  murals along  with  gum  as  binder  and  did  not  find  application  in  textiles.

Bacterial  and  fungal  origin  dyes …

Some  bacteria  also  produce  coloured  substances  as  secondary  metabolites.  Bacillus Brevibacterium, Flavobacterium, Achromobacter, Pseudomonas, Rhodococcus  spp. are some  of  the  pigment  producing  bacteria. Serratia  marcescens  produces  deep  red pigment. Some  bacteria  have  also  been  reported  to  produce  indigo  upon  exposure  to petroleum  products. Pigments  from  fungus  Monascus  purpureus  are  used  for coloration  of  some  traditional  oriental  food  items  and  also  for  fabric  coloration. Orchil  dye  from  lichens  was  used  for  violet  and  purple  shades  as  a  cheap  alternative  to  expensive  Tyrian  purple. Some  mushrooms  are  also  known  to  yield dyes. These  were  extensively  used  in  Europe  for  dyeing.  Cortinarius  species  have intensely  colored  fruiting  bodies  and  are  reported  to  be  the  best  mushroom  dyes. Cortinarius  sanguineus (blood – red  webcap)  contains  about  6%  red  pigments. Apart  from  the  above  mentioned  sources, various  researchers  have  been  exploring local  flora  for  its  potential  to  dye  textiles. Leaves, flowers, wood, bark  etc. of  several plant  materials  have  been  utilized  for  dyeing  of  various  textile  substrates  with varying  results  in  terms  of  deepness  of  color  produced  on  textile  substrates  and  its colorfastness  properties. Every  year  new  additions  are  being  made  to  the  list  of  plant  species  which  can  be  used  as  dye  source.

Dye  Extraction …

Unlike  synthetic  dyes  which  are  available  in  a  purified  ready  to  use  form, natural dye  bearing  materials  contain  only  a  small  percentage  of  coloring  matter  along  with a  large  quantity  of  other  plant  or  animal  constituents  and  therefore  extraction  of colouring  matter  is  an  essential  step. Most  of  the  practitioners  prepare  their  own dyes. It  is  economical  and  also  ensures  authenticity. Dye  extract  is  prepared  by soaking  the  dye  containing  material (after  powdering  for  hard  materials  like  bark, roots,  wood   etc. in  water  in  earthen  or  metal  (stainless  steel  or  copper) vessels  and then  boiling  and  simmering  the  solution. Residual  matter  is  then  removed  by filtering  through  a  cloth  and  the  extract  is  used  for  dyeing. Sometimes, depending upon  the  dye  material, addition  of  acidic  or  alkaline  substances  such  as  vinegar  or lime  may  facilitate  better  dye  extraction. It  may  also  change  the  hue  of  dye  by changing  the  dye  components  that  get  extracted. Indigo  is  extracted  by  an  entirely  different  process  known  as  fermentation. Freshly harvested  indigo  leaves  and  twigs  are  soaked  in  warm  water  whereby  the  indigo present  in  the  leaves  as  glucoside  gets  released  by  the  action   of  an  enzyme,  also found  in  leaves. The  fermentation  is  complete  in  about  10-12  hours  and  the  greenish yellow  liquor  containing  the  indigo  is  then  transferred  to  beating  vats. Here  it  gets oxidised  by  the  atmospheric  air  to  the  blue  colored  indigotin  which  settles  down  at the  bottom. It  is  collected, washed  and  after  removing  excess  water  is  pressed  into cakes  and  marketed.

Application  of  Natural  Dyes …

Natural  dyes  are  generally  used  to  dye  textiles  made  of  natural  fibres  like  wool, cotton  and  silk  where  they  strengthen  their  inherent  eco-friendly  nature  though dyeing  of  synthetic  fibre  textiles  such  as  polyester, nylon  etc. has  also  been  reported. Natural  dyes  can  be used  to  dye  textiles  at  all  stages  such  as  fibre, yarn  or  fabric. Wool  is  generally  dyed  in  yarn  form  and  traditional  dyers  almost  always  prefer  yarn dyeing  for  all  materials  as  it  offers  versatility  in  designing  during  weaving. As  in synthetic  dyeing, the  textile  material  to  be  dyed  is  first  made  free  from accompanying  impurities  like  wax, pectin, oil, grease  etc. and  made  white  and absorbent. Traditionally, multiple  treatments  with  sheep  or  cow  dung  along  with alternate  wetting  and  sun  bleaching  of  the  fabric  were  used  to  achieve  this  and  the process  used  to  take  many  days. Presently, the  fabric  is  generally  scoured  with  soap or  alkali  and  bleached  with  hydrogen  peroxide  to  quicken  the  process. For  synthetic  dyes, the  amount  of  dye  used  is  normally  given  as  %  shade  which  is the  amount  of  dye  used  to  dye  100  gram  fabric. The  same  convention  may  be  used for  natural  dyes. As  the  actual  dye  content  of  the  natural  dye bearing  materials  is very  low, it  is  common  to  use  15-25 % shade  whereas  only  about  1-3 %  shade  is required  for  synthetic  dyes  as  these  are  purified  chemical  products.

Mordanting  …

Only  a  few  natural  dyes  like  turmeric  can  directly  dye  textile materials  and  are  called  direct  dyes. Majority  of  natural  dyes  need  mordants  for fixing  on  to  the  textiles  particularly  for  cellulosic  textiles  like  cotton  which  unlike wool  and  silk, do not  have  amino  or  carboxyl  group  for  attaching  with  the  dye  molecule. Mordants  are  the  substances  which  have  affinity  for  textile  fibres  as  well as  dyes  and  thus  act  as  a  link  between  them. Such  dyes  are  known  as  mordant  dyes.

Advantages  of  Natural  Dyes …

Natural  dyes  are  eco – friendly  as  these  are  obtained  from  renewable  resources  as compared  to  synthetic  dyes  which  are  derived  from  non – renewable  petroleum resources. They  are  biodegradable, hence  the  effluent  produced  in  natural  dyeing  can be  easily  treated  thereby  reducing  the  pollution  from  dyeing  units. The  residual vegetable  matter  left  after  extraction  of  dyes  can  be  easily  composted  and  used  as fertilizer. They  produce  soft  colours  which  are  soothing  to  the  eye  which  are  in harmony  with  nature.

Plants  irrigated  with  natural  dyeing  plant  effluent  at  Wardha,  Maharashtra.

Plants irrigated with natural dyeing plant effluent at Wardha, Maharashtra.

In  addition  to  these  environmental  benefits, natural  dyes  also  offer  functional benefits  to  the  wearer  and  users  of  such  textiles. Many  of  the  natural  dyes  absorb  in  the  ultraviolet  region  and  therefore  fabrics  dyed  with  such  dyes  should  offer good  protection  from  ultraviolet  light. Tannin  treatment  during  mordanting  itself  is able  to  improve  the  UV  protection  of  textiles. Many  natural  dye  materials  possess antimicrobial  properties  and  therefore  dyed  fabrics  have  been  reported  to  be  odour free  by  the  users. These  fabrics  were  also  found  to  be  mosquito  repellent  and /or moth  repellent. Many  natural  dyes  such  as  myrobolon  fruits, turmeric, manjishth root, Arjuna (Terminalia arjuna) bark, safflower  florets  etc. possess  curative  properties   and  have been  used  in  traditional  medicinal  systems  and  these  benefits  may  reach  the  wearer by  absorption  of  medicinal  compounds  through  skin. Textiles  produced  in  Kerala, India  by  dyeing  with  herbs  as  per  the  traditional  Ayurvedic  system  of  medicine  are known  as  ‘Ayurvastra’  and  have  become  popular  as  health  and  well – being  textiles and  are  being  exported  to  various  countries. Various  companies  are  now  marketing naturally  dyed  textiles  as  health  and  well – being  textiles.

Limitations  of  Natural  Dyes …

In  spite  of  their  several  advantages, natural  dyes  at  present  are  not  part  of  the mainstream  textile  processing. Less  than  1 %  of  textile  production  is  being  dyed  with natural  dyes  and  they  are  mainly  used  in  cottage  sector  or  small  scale  processing units. Their  limited  shade  range  and  inability  to  dye  synthetic  fibres  like  cellulose acetate, polyester etc. and  also  availability  and  supply  issues  are  a  big  hindrance  for wider  adoption. At  the  present  level  of  world  textile  production,  natural  dyes  can only  replace  a  fraction  of  total  textile  dye  consumption  as  food  crops  are  the  first priority  for  land  use. There  is  a  danger  of  deforestation  if  already  depleting  forest cover  is  over  exploited  for  use  in  dyeing. It  is   due  to  these  issues  that  though natural  dyes  would  be  the  first  option  for  dyeing  organically  grown  textile  fibres, Global  standard  for  Organic  Textiles (GOTS)  has  also  permitted  the  use  of  safe synthetic  dyes. Exploitation  of  the  by  products  and  waste  material  from  food processing   industry  and  establishment  of  collection  and  supply  mechanism  for  some agro  by  products  and  forest  products  would  be  of  help  in  improving  the  natural dyes  availability.  Use  of  non  eco friendly  mordants  by  some  processors  due  to  their ignorance, makes  the  natural  dyeing  application  process  non  eco- friendly  and  false claims  of  natural  dye  usage  for  synthetically  dyed  textiles,  are  the  issues  affecting both  consumers  and  natural  dyeing  practitioners  and  need  to  be  tackled  with training  and  government  initiatives.

Conclusion …

Policy  incentives  to  promote  better  utilization  of  agro  and  agro  processing  residues, cultivation  of  dye  plants  in  wastelands  and  setting  up  of  natural  dyeing  units  would help  in  popularizing  use  of  natural  dyes. Establishment  of  proper  characterization and  certification  protocols  for  natural  dyes  textiles  dyed  with  them  would  improve the  consumer  confidence  in  such  textiles  and  benefit  both  producers  and  consumers. In  future, if  the  availability  of  natural  dyes  can  be  increased  to  very  high  levels  by biotechnological  interventions  such  as  tissue  culture  or  genetic  engineering  resulting in  mass  production  of  these  dyes  by  microbes  at  low  costs; their  usage  can  become sustainable  for  main  stream  textile processing. At  present, use  of  natural  dyes  is sustainable  only  for  small  scale  applications  and  they  can  complement  synthetic  dyes  as  an  eco  friendly  option  to  the  environment  conscious  consumer.

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Dr. Sujata  Saxena

Dr Sujata Saxena

Dr. Sujata Saxena  has  a  Ph.D.  in  Chemistry  and   is  currently  working  as  Principal  Scientist  and Head  of  Chemical  and  Biochemical  Processing  Division  at  Central  Institute  for  Research  on  Cotton Technology  (CIRCOT), Mumbai. Her  current  research  interests  are  pre-processing, dyeing  and finishing  of  cotton  and  its  blends  using  natural  and  eco-friendly  agents  and  processes. She  has special  interest  in  developing  methods  for  application  of  natural  dyes  to  cotton  and  in  improving their  colourfastness  properties.

She  has  been  a  consultant  to  National  Handloom  Development Corporation (NHDC), Lucknow  for  developing  methods  for  dyeing  of  cotton  textiles  with  lac, berberin  and  manjitha  natural  dyes. She  was  also  associated  with  multi- institutional  projects funded  by  UNDP (United Nations Development Programme) and  ICEF (India- Canada Environment Facility) on  development  and  promotion  of  natural  dyes  for  cotton.

She  has  published  more  than  45  scientific  papers, articles  and  book  chapters, has  applied  for  4 patents  and  has  presented  more  than  a  dozen  papers  at  national  and  international  Conferences.

She  has  been  associated  with  National  as  well  as  International  professional  societies  and  is currently  Joint  Secretary  of  the  Indian  Fibre  Society, Mumbai  and  Treasurer  of  Indian  Society  for Cotton  Improvement, Mumbai. She  has  recently  been  awarded  the  Fellowship  of  Textile Association  of  India, Mumbai. She  has  been  associated  with  various  BIS  sub-committees  on  textiles  and  is  a  reviewer  for  National  and  International  journals.

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3 Responses to Natural dyes – the eco friendly alternative !

  1. Dr. Sujata Saxena says:

    The article has taken a really good shape and is pleasant to read. The green background is very apt and soothing. The colourful photographs of flowers in the beginning as also the photographs of dyed fabrics are very good and complement the article well.

  2. Saudamini Shevade says:

    Dear Dr. Saxena,

    Thank you for the great article! It was not only informative, but also insightful. The analysis of the reasons why natural dyes haven’t entered the mainstream industry was very interesting to read. I hope a good balance can be found between being eco-friendly and the commercial considerations for production of naturally dyed textiles, and more and more people start using them as a more eco-friendly alternative.

    Thanks to TheUntamedEarth team for hosting the article!

    - Saudamini

    • Thank you for your comments and observations. TheUntamedEarth would be delighted to bring more of such interesting stories to our readers. Would be only too happy to see environment friendly processes become mainstream … and not just for dyes.

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