PLANTS AND PEOPLE--Dyes

The powerpoint for this lab is here.

 

INTRODUCTION

 

We live in a colorful world, surrounded by food, fabric, leather, paper, plastics, and so on that have been dyed. Dyes offer us beauty and a chance for self-expression. Today we will study the history of dyes and the dyeing process. We will dye some fibers with natural dyes using the solar dyeing method.

Objectives for this part of the lab are to:

learn the components and qualities of dye and mordant mixtures

□ outline the steps in the dyeing process

□ learn about the properties of various types of dyes

□ study the plants used to make dyes–indigo, madder, turmeric, etc.

discuss how natural dyes differ from synthetic dyes

dye some fibers with the solar dyeing method

 

Safety concerns:

Some mordants are highly toxic or corrosive. We will use safer alternatives, but wear appropriate

    gear (gloves, eye protection) and use caution.

□ Dyeing is wet and messy. Wipe up any water that spills on the floor.

Use caution with clippers, knives, and other methods of chopping up dyeplants

If you have skin allergies, wear gloves and be careful when handling dyeplants.

The blender is electric; we are using lots of water. Be careful mixing the two.


WHAT IS A DYE?

 

A dye is a soluble, colored substance that has an affinity for a fiber or other substance, meaning that it will adhere to the surface. (In contrast, a pigment is insoluble an usually has no affinity.) Dyes can be made from plant, animal, and mineral substances.

 

HISTORY OF NATURAL AND SYNTHETIC DYES

 

In the beginning, all dyes were made from natural substances. When the first man sat on the first berry, he discovered dye. The oldest known dyed articles date to about 36,000 years BP. By about 5,000 years ago, dyes were widely used. Throughout history, colored fabrics have signified wealth, status, occupation, etc. Like spices, dyestuffs are light, easy to ship, and often non-perishable, so they were valued and expensive trade goods, along with other substances used in the dyeing process.

 

Natural dyestuffs produce beautiful, nuanced colors, but they may be laborious to collect or process and can vary widely from batch to batch. Also, natural dyes only work on natural fibers or fibers derived from cellulose–wool, cotton, silk, ramie, hemp, wood, rayon, etc. They will not dye man-made fibers such as polyester, vinyl, spandex, and so on.

 

The first synthetic dye was produced in 1856, and since the Industrial Revolution, chemists have developed thousands more. Synthetic dyes are cheap to produce, do not vary from batch to batch, and will dye a wide range of substances. However, some of them may be dangerous to handle.

 

So why use natural dyes? For beauty–the colors have a depth that synthetics often cannot match, and they all seem to go together. For fun–there is always an element of surprise, as slight variations in dyestuff, water, and process can produce unexpected results. For a link with the past–the dyestuffs our distant ancestors used are mostly still available.

 

FASTNESS

 

Fastness refers to the permanence of a dye. A light-fast dye will not fade with exposure to sun, and a wash-fast dye will not fade with laundering.

 

 

THE COMPONENTS OF THE NATURAL DYEING PROCESS

 

Dyestuff–This is the plant material being used. Depending on the plant, the dye may be found in the roots, leaves, fruit, flowers, stems, and/or wood. Sometimes one plant can produce a whole range of colors. Hundreds of “recipes” exist. The usual ratio is one pound of plant material to one pound of fiber.

 

Mordant–A mordant is a chemical which helps the dye molecules adhere to the fiber and stay there. That is, they help dyes be more fast. Many are metal salts and were discovered when dyers noticed that dyepots made of different materials yielded different colors. Different mordants work best with different dyestuffs and fibers. Some dyes need no mordant.

 

1. iron–makes colors darker
2. alum, aluminum, chrome, tin--brighter or different shades
3. copper (sulfate)--greener
4. urea
--often from human waste Don’t laugh! Some of the most prized shades in history depended on urea, and dyers used to keep a large vat into which passers-by could urinate.

 

STEPS IN THE NATURAL DYEING PROCESS

 

It is vital to keep a record of the whole process so that pleasing results can be duplicated and failures can be avoided in the future.


 A. Wash fiber–Remove oil, dirt, sizing. Fibers must be wet for dyeing. The water used makes a difference. Most tap water has salts which will affect the color for good or ill.

             B. Gather plant–Approx. 1 lb per lb of fiber, be responsible in gathering

             C. Make dyebath–Chop the plant, then boil, simmer, or ferment to extract the dye

 D. Mordant– Fiber is soaked in mordant before dyeing or rinsed with a mordant solution after dyeing.

             E.  Dye–Simmer-dyeing works with most. Some dyes require a cold-fermentation process. Solar dyeing involves soaking in a clear glass jar in sunlight over several days.

             F.  Rinse –To remove excess or unadhered dye molecules.

             G. Dry–Usually away from sunlight.

 H. Additives–Sometimes compounds are added to the dyebath or rinse water to adjust the color--salt, vinegar, iron, tannic acid, etc.

          

 

WHICH PLANTS TO USE?

 

Again, results are not wholly predictable and will vary with plant, season, temperature, fiber, mordant, strength and length of dyebath, post treatment, water quality and pH, and storage. There are guidebooks which will tell you which local species may be used, and there are mail-order houses which sell prepared dyestuffs

 

1. red --madder, cochineal (actually comes from an insect that feeds on prickly pear cacti), brazilwood (Brazil was named after the dye found in a species of indigenous tree!)

            2. orange/gold/yellow -- weld, onion, goldenrod, osage orange, saffron, turmeric, many others

            3. green --blue over yellow, sedges

            4. blue --logwood, woad, indigo (needs fermenting), alkanet (purple-blue)

            5. purple --orchil lichens (rare), cabbage, berries

            6. tan/brown/black –walnut, oak galls; often with an iron mordant or tannic acid treatment

 

 


ACTIVITY: SOLAR DYEING

 

We will dye fiber in lab this week. We’ll use the solar-dyeing method because it eliminates the need to simmer the fiber in the dyebath for long periods of time. We will choose dyeplants and mordants that are safest to work with, avoiding the toxic mordants such as chrome and aluminum salts. We will use a dyeplant that is locally abundant. We might also try a purchased dyestuff such as madder or indigo.

 

We will need:

 
kitchen scale

wool yarn

cotton fabric prepared for dyeing

dyeplants

knives and cutting boards

non-reactive pot for extracting dye, mordants

alum (mordant)

salt

measuring spoons

hotplate


 

scissors and clippers

large glass jars with lids

spoons

rubber gloves

eye protection

lots and lots of water

lab coats or aprons

soap, if needed for pre-washing fiber


NOTE: Recipes will vary for the particular plant you are using and the fiber you are dyeing. Keep a record of what you do.

 

Prepare the plant according to the recipe. This usually involves chopping it into small pieces and boiling or simmering it to release the dye. Let the dyebath cool.

 

Wash the fiber if necessary. Cloth labeled PFD (prepared for dyeing) does not need to be washed.

 

Prepare the mordant bath, being careful to measure accurately. Soak the fiber well in water and then follow the recipe for the time and temperature of the mordant bath. Rinse the fiber afterwards, if the recipe tells you to do so.

 

Place the dyebath and the fiber in a large, lidded glass jar. Depending upon the recipe, you may also be adding the remains of the dyestuff. Place the jar in a bright, sunny window. We will check the jars in a week. When we are pleased with the results, we will rinse and dry the fiber.

 

 

QUESTIONS FOR THOUGHT, REVIEW, AND STUDY: Refer to lecture, Powerpoint, textbook, and lab notes, as well as to what you learned and observed during the laboratory activity.

 

 

1. What is a dye?

 

2. What is one plus to using natural dyes rather than synthetics? What is one drawback?

 

3. From what part(s) of the plant are dyes obtained? Is it the same for all plants?

 

4. What is a good rule of thumb for the ratio of plant to fiber for natural dyeing?

 

5. On what sorts of fibers will natural dyes work? On what will they not work?

 

6. What is a mordant? Which one did we use and why?

 

7. What are the components of the natural dyeing process?

 

8. What are the steps in the natural dyeing process?

 

9. Why is it important to keep a detailed record of each dyeing event?

 

10. What is meant by fastness?

 

11. Name some important natural dye plants and the colors they produce.



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last updated 12-13-2010