Dyeing materials with plants is an ancient art practiced since biblical times. There are many plant materials that can be used for dyeing yarns and materials: roots, bark, leaves, berries, seeds, twigs, branches, tubers, and nuthulls, each capable of producing a range of colors with various mordants and yarns. In addition, when properly applied, natural dyes are fast, resisting fading due to exposure to sunlight.


Although there are many recipes for natural dyes, this experiment will only be concerned with a simple recipe for the preparation of a dye bath and the use or mordants to provide a variation in colors.


Mordants are chemical additives that sometimes help a fiber accept a dye that it might otherwise reject. (The word mordant comes from the Latin "morders" which means "to bite") Some of the more common mordants are listed in the table below.

 


Although you will be doing this process as a laboratory exercise, it is, not necessary to work in a laboratory or with highly technical equipment to do natural dyeing. You can easily work on a kitchen range, household-type hot plate or even an open fire and get equally good results. Remember to use soft water and utensils made of glass, stainless steel or enamel in order to get true colors. Don't forget to protect your hands with rubber gloves to prevent dye stains and to prevent excessive exposure to mordants.


Safety Precautions


  • Wear goggles at all times in the laboratory.
  • Wear rubber or plastic gloves when working with mordants and dye baths.
  • All the mordants used in this experiment can cause minor respiratory irritations if inhaled and possible mild skin irritation. In the event of skin contact, wash the affected areas with water.


Disposal


  • Dispose of all mordant solutions in the containers provided in the laboratory.
  • Solutions of natural plant dyes can be poured down the drain with running water.


 

Materials Needed


  • 400-mL beakers
  • Glass stirring rod
  • Funnel
  • Filter paper
  • Forceps or tongs
  • Beaker tongs
  • Alum, aluminum potassium sulfate, KAl(SO4)212 H2O
  • Cream of tartar - potassium bitartrate, KHC2H4O6
  • Iron (II) sulfate, FeSO47H2O
  • Tin (II) chloride, SnCl2
  • Potassium dichromate, K2Cr2O7
  • Suggested plant material: onion skins (red or yellow); marigold flowers; snapdragons; zinnia; tomato vines, coffee and tea
  • 2 x 5 cm strips of cotton, wool, and silk


Procedure


Preparation of dye bath


  • Add enough plant material to a 400-mL beaker to cover the bottom, (at least 10 g). Add 50 mL of distilled or deionized water (or enough to cover the plant material).
  • Heat the mixture to boiling and boil it for about 20 minutes. Occasionally add distilled water to replace any water that boiled away.
  • Filter the hot solution and discard any plant material left in the filter paper.
  • Dilute the filtered solution with distilled water to 200 mL.


Preparing the cloth for dyeing


  • Weigh out 0.3 grams of aluminum potassium sulfate and add to a 400-mL beaker. Weigh out 0.1 gram of potassium bitartrate and combine it with the alum. Add 100 mL of distilled water to the beaker.
  • Add 1 strip each of cotton, wool, and silk to the solution and heat to boiling. Remove the solution from the heat and let stand for 5 minutes.
  • Remove the cloth strips and press the excess solution from it. The cloth is now ready for dyeing.
  • Repeat the above procedure using 0 .2 grams of iron (II) sulfate in 100 mL of distilled water.
  • Repeat the above procedure using 0.2 grams of tin (II) chloride in 100 mL of distilled water.
  • Repeat the above procedure using 0.2 grams of potassium dichromate in 100 mL of distilled water.


Dyeing the Cloth


  • Heat the dye bath to boiling and lower the heat to maintain it at a simmer.
  • Add the three strips of material that were treated with the alum-cream of tartar mordant and continue to simmer for 5 to 10 minutes.
  • Remove the cloth strips from the dye bath and rinse them in a beaker of hot distilled water. Then repeat the rinse in a beaker of room temperature distilled water, continue to rinse until no more color is coming from the material.


  • Label the cloth immediately with name of plant material used and the mordant.
  • Repeat the dyeing process using the same dye bath and the material treated with the iron (II) sulfate.
  • Repeat the dyeing process using the same dye bath and the material treated with the tin (II) chloride.
  • Repeat the dyeing process using the same dye bath and the material treated with the potassium dichromate.
  • Repeat the dyeing process using the same dye bath and some cloth strips that have been wetted with distilled water. (Press out excess water.)


For your laboratory report, compare the colors obtained with the different mordants and materials.

 

References


Natural Plant Dyeing, A Handbook, Brooklyn Botanic Garden, Brooklyn, N.Y. (May be out of print. Contact Brooklyn Botanic Garden, 1000 Washington Ave., Brooklyn, N.Y. 11225, or www.bbg.org on the Internet)


Natural Dyes: Plants and Processes, Jack Kramer, Charles Scribner's Sons, New York, N.Y., 1972


If you are interested in trying some natural dyeing at home, consult the above books or check your local library or book store. Also check online at www.amazon.com or www.barnesandnoble.com



About the Author:


The author is associated with Department of Chemistry, Pima Community College, USA.


Originally Published at:


http://www.chymist.com/Natural%20dyes.pdf



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