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Staining Science: Make the Boldest, Brightest Dye!

A colorful challenge from Science Buddies



George Resteck

Key concepts
Chemistry
Dyes
Fabric

Introduction
Have you ever wondered about the materials that make up your clothes and why some look and feel different from others? The clothes you wear are made of fibers that come from many different sources. Some fabrics are made from natural fibers and others are from manufactured, or totally synthetic, fibers. In this activity you'll explore how well different fiber types can be dyed using fiber-reactive dye. Aren't you just dye-ing to find out which fabric works best?

Background
From woven mummy shrouds in ancient Egypt to the ornate ball gowns ladies wore in the Victorian era to the tie-dyed shirts that gained popularity in the 1970s, dyed cloth has played an important role in human culture. Its production has also changed over time. Early dyes were made using natural resources, like plants, berries, minerals and seeds. The cloths, just like the dyes, were made from a natural resource—such as cotton, linen, wool or silk. Cotton and linen fibers are all formed from cellulose, the main component of plant cell walls. Wool and silk are animal-protein-based fibers.

Later, as advancements were made in chemistry and manufacturing, people learned to make other fibers, including polyester, nylon and rayon, which are known as synthetic fibers. Today's dyes are also different—they are now often made with artificial chemicals. By understanding how the molecules of dye react with the different types of fibers, chemists can design many vibrant and color-fast dyes (which means that they won't fade or run) and figure out on which fiber types they work best.

Materials
• Three different types of white fabric samples: such as linen, cotton–polyester blend, 100 percent polyester, 100 percent cotton, wool, rayon, silk and nylon. Collect enough to make at least one 10-inch by 10-inch square of each type. Preferably select one natural fabric, a synthetic one and one that is a blend of both. Scraps from old pillow cases, sheets, rags or unwanted clothes can make good sources—just be sure they are okay for discard and that you know the fabric type. Otherwise, small pieces can be purchased from a craft or fabric store.
• Ruler
• Scissors
• Permanent marker
• Newspaper or rags
• Measuring cup, which will not be used for cooking afterward (If unavailable, create a discardable plastic cup measurer. To do this, measure out one half cup of water, pour it in the disposable cup and mark the top of the water with a permanent marker. Dump out the water and repeat with one full cup. Use this marked container as your measuring cup.)
• Laundry detergent
• Safety goggles or protective glasses
• Rubber gloves
• Clean glass jar, at least 10 fluid ounces. It should not be used to consume food or beverages afterward
• Measuring teaspoon and tablespoon. (They should not be used for cooking afterward. If unavailable, measure one teaspoon of water into a disposable plastic spoon and note the quantity. Repeat with the tablespoon.)
• Fiber-reactive dye powder, such as Tulip Permanent Fabric Dye or Procion Pro MX Reactive Dye, often available at a craft and or fabric store. Use a bold color, like red, blue or green
• Salt
• Water
• Sealable plastic bag, one-gallon size
• Timer or clock
• Soda ash or Arm & Hammer Super Washing Soda
• Plastic container that can hold four cups comfortably. (It should not be used for food or beverage afterward.)
• Old clothes to wear that can get stained

Preparation
• Cut at least one 10-inch by 10-inch square out of the each fabric sample (linen, cotton-polyester and 100 percent polyester, for example).
• Use the permanent marker to label each square with its fabric type. Because the permanent marker may leak through some types of fabric, if you are not working on a surface that can be stained, label the fabrics on top of newspaper or rags.
• Prewash the fabric squares by putting them in a normal clothes washing machine with laundry detergent. Wash using hot water, if possible. Allow the fabric squares to air dry.
• Before opening the dye powder packet, cover the area you will be working on with newspaper or rags so that you will not stain it. You might want to work outside to avoid staining something. Also put on clothes that you would not mind staining.
• Dyes often contain soda ash (sodium carbonate), which is caustic. Wear goggles and gloves when mixing the dye solution, mixing the soda ash solution and rinsing the fabric samples after dyeing.

Procedure
• Put on gloves and safety goggles.
• Put two teaspoons of powdered dye, one tablespoon of salt and one cup of warm water into the glass jar. Mix thoroughly. How does the dye look?
• Wet the fabric squares with water and place them in the sealable plastic bag. Carefully pour the dye solution into the bag then add one half cup of water. Seal the bag, trapping as little air as possible. How does the fabric change when the dye is added?
• Let the bag sit for 20 minutes. Every couple of minutes, gently squeeze the bag to coat all of the fabric samples.
• While the fabric is soaking, mix one tablespoon of soda ash (or Arm & Hammer Super Washing Soda) with two cups of warm water in the plastic container. Break up any hard pieces that form.
• After the fabric is done soaking, carefully open the plastic bag and add one half cup of the soda ash solution. Reseal the bag, trapping as little air as possible.
• Gently squeeze the bag to mix the soda ash, dye and fabric. Let the bag sit for one hour, gently squeezing every 10 minutes or so.
• With gloved hands, reach into the bag and retrieve the fabric samples and place them on a surface where they will not stain anything. Carefully dump the contents of the bag into a sink (pouring directly into the drain so as not to stain any of the sink area).
• Rinse the fabric until the water runs clear. When you are done handling the rinsed fabric and disposing of the soda ash solution, you can remove your goggles and gloves. Wash the fabric samples in the washing machine just as you did before (but not with any other clothes). Allow the samples to air dry.
Once they're dry, how do the fabric samples look? Did some types of fabric become dyed to a darker shade than others? Did some types not absorb much dye at all?
Extra: In this activity you tested how well different fabric samples dyed using a fiber-reactive dye. But there are many other types of fabric you could test dyeing, and they may react differently. How well do other types of fabric become dyed with a fiber-reactive dye?
Extra: Before synthetic dyes were created, humans used natural dyes. Do some background research and pick one or more natural dyes to try in this activity. You will probably want to use relatively safe dyes, such as turmeric or berries. Be just as careful with these around other surfaces and materials, as they also stain easily. Do some natural dyes work better than others? Does it depend on the type of fabric used?

Observations and results
Did coarse, natural fabrics, such as linen or 100 percent cotton, become dyed the darkest shade? Did synthetic fabrics, such as polyester or rayon, remain nearly white? Did fabrics that were a blend of natural and synthetic fibers become noticeably dyed, but not quite as dark as fully natural fabrics?

Cotton and linen fibers are both natural fibers made from cellulose, a compound found in plant cell walls. Fiber-reactive dyes form permanent covalent chemical bonds with cellulose, making this dyeing process a relatively permanent one. Polyester, however, is a synthetic fiber that does not react with fiber-reactive dyes in this way and cannot be effectively dyed using them. For polyester to be successfully dyed a different category of dyes must be used—specifically dispersion dyes, and a great deal of heat has to be applied during the dyeing process. In this activity you probably saw that synthetic fabrics were not effectively dyed, remaining nearly white, whereas the natural fabrics dyed the darkest shade and the blend fabrics were not quite as dark as the natural fabric (depending on the percentage of natural and synthetic fibers in the fabric).

Cleanup 
You can safely pour the extra soda ash solution down the drain, flushing with water. Do not use the measuring cup, measuring spoons, plastic container or glass jar for cooking or food afterward. Carefully rinse and then recycle the plastic sealable bag.

More to explore
Fiber-Reactive Dye Chemistry, from Dharma Trading Co.
About the Dyes, from Paula Burch's All About Hand Dyeing
How to Make the Boldest, Brightest Tie-Dye!, from Science Buddies

This activity brought to you in partnership with Science Buddies
ScienceBuddies

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