This fabric dye chemistry experiment explores the way a dye produces different colors, depending on the nature of the fibers. A single dye mixture produces a whole rainbow of colors on different materials because of the chemical bonding between the dye and the polymer. Here is how you perform the demonstration, with tips and options for substitutions.
Overview of the Fabric Dye Chemistry Experiment
This project involves a mixture of three dyes. On their own, these dyes are red, blue, and yellow, so all of the colors of the rainbow are possible. Several factors determine the color you get from dyeing cloth. Coloring results from chemical bonding, diffusion, absorption, of a combination of these processes. The temperature of the dye bath and the time allowed for the process also affect the outcome. Dyes are available from Philip Harris (International), Kemtex (UK), or (for the alternative dyes) from Flinn Scientific (US).
- Acid dyes, like acid blue 40, contain -CO2H or -SO3H groups that bond to the basic -NH groups of amide linkages, such as those found in nylon, silk, and wool.
- Direct dyes, like direct red 23, bond to fibers via hydrogen bonding. They deposit color onto fibers with numerous –OH groups, such as cotton, linen, rayon, and viscose.
- Disperse dyes, such as disperse yellow, are insoluble in water. Instead, they form a suspension (dispersion) in the liquid that absorbs onto hydrophobic polymers, such as polyester. They also attach somewhat to cellulose fibers and other polymers that accept direct dyes.
The colorfastness of a dye depends on how the molecule size, how tightly it bonds to the fibers, and how soluble it is in a cleaning solvent (usually water).
Materials
- 0.06 g acid blue 40
- 0.04 g disperse yellow
- 0.04 g direct red 23
- small volume of dilute hydrochloric acid (~2 M)
- heat-safe (Pyrex) glass beakers or cups
- Bunsen burner or other heat source
- Tongs or forceps
- Paper towels
- Water
- white fabric samples
- cotton
- wool
- nylon
- polyester
- polyester cotton blend
- triacetate (cellulose acetate)
- acrylic
- silk
Once the dye baths are set up, the experiment takes about 30 minutes to complete.
Perform the Fabric Dye Chemistry Experiment
- Either label the fabric swatches with a permanent marker or else cut them into distinctive shapes that identify them (e.g., star is cotton, heart is wool, etc.).
- Weigh and label two 0.02 g samples of the red and yellow dyes and two 0.03 g samples of the blue dye.
- Prepare the dye bath containing all three chemicals: Dissolve 0.02 g red, 0.02 g yellow, and 0.03 g blue into 200 ml of water. Add a few drops of dilute hydrochloric acid. Heat the dye mixture to boiling.
- Prepare dye baths for the individual colors. In the red bath, use 0.02 g of red dye in 200 ml of water. The yellow bath is 0.02 g of yellow dye in 200 ml of water. The blue bath is 0.3 g of blue dye in 200 ml of water. Add a few drops of dilute hydrochloric acid to each container and heat it to boiling.
- Dye each fabric sample by simmering it for 5 to 10 minutes in the desired dye bath.
- After dyeing, remove fabric strips using tongs or forceps, let excess dye drip back into the container, and rinse with running water.
- Either hang the strips to dry or else place them on paper towels.
- Compare the colors of the fabric strips and use what you know about the chemical structures of the fibers to explain your findings.
Further Research
- Now, turn it from a project into an experiment by predicting the colors of fabrics you did not test, based on their chemical properties. Then, dye these fabric swatches and see if the colors support your hypothesis.
- Other investigations include testing the effect of a mordant, such as salt or alum, seeing if changing the pH of the dye bath changes the colors, or playing with the time and temperature of the dyeing process.
Expected Colors
Here are typical colors for various fabrics, based on a 10 minute dyeing time:
| Dye | Wool | Silk | Nylon | Acetate | Cotton | Polyester | Cotton/Poly Blend |
|---|---|---|---|---|---|---|---|
| Mix | olive green | olive green | olive green | yellow | red | yellow | orange |
| Red | orange-red | orange-red | orange-red | nearly white | red | pink | pink |
| Blue | blue | blue | blue | white | pale blue | white | nearly white |
| Yellow | orange | orange | orange | vivid yellow | pale yellow | vivid yellow | vivid yellow |
Substitutions
Alternatively, use dyes common in chemistry. The difference here is that you don’t combine all of the dyes into one bath. Instead, keep the dyes separate and compare the color results using different fabrics. The chemical properties of these dyes differ because of the purposes they serve in the lab. So, they produce various colors on cloth due to the chemical bonding of the polymers. Here are some good options:
- Alizarin red, 1%
- Congo red, 0.1%
- Crystal violet, 1%
- Malachite green, 1%
- Methyl orange
- Place each dye in a separate container and heat it to near boiling.
- Mark fabric strips to identify their composition.
- Soak each fabric strip 5-10 minutes in a dye.
- Remove it using tongs or forceps, letting excess liquid drain back into the dye bath.
- Pat each strip dry with paper towels to remove excess dye.
- Rinse the strips with running water.
- Compare the colors obtained by each fabric using the dyes.
Table of Dye Colors for Different Fabrics
While your results may vary, largely depending on the pH of your water, expect colors like this:
| Dye | Wool | Acrylic | Polyester | Nylon | Cotton | Acetate |
|---|---|---|---|---|---|---|
| Alizarin | violet | light pink | pink | lavender | mauve | cream |
| Alizarin + Alum | deep purple | purple | purple | purple | purple | purple |
| Congo red | red | pink | pale pink | bright pink | dark red | red |
| Crystal violet | deep purple | lavender | pale blue | deep blue | royal blue | deep blue |
| Malachite green | deep green | blue green | pale green | light green | blue green | turquoise |
| Methyl orange | red-orange | white | light yellow | orange | light yellow | yellow |
Tips and Safety
- If you don’t have all of these fabrics, scavenge thrift shops or ask participants if they have any scrap material at home. Either use fabric that bears a label or else use the response to the dye to identify the fabric composition.
- Ideally, you want white starting material, but you can bleach and dry colored fabrics before performing the experiment.
- Wear gloves (preferably nitrile) and eye protection. Most dyes irritate skin and color skin or clothing. If you splash dye onto your skin, rinse it off immediately with running water.
- Although the hydrochloric acid is dilute, it can still cause a chemical burn. Neutralize a spill or splash with a weak base, such as baking soda, and then rinse with water.
- If possible, store dyes and perform the experiment within a fume hood. Otherwise, conduct the project in a well-ventilated area.
- Because these dyes are hot, take care to avoid getting burned.
References
- Bien, Hans-Samuel; Stawitz, Josef; Wunderlich, Klaus (2005). “Anthraquinone Dyes and Intermediates” in Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim. doi:10.1002/14356007
- Cesa, I. (ed.). (2004). Flinn ChemTopic Labs. Volume 5: Chemical Bonding. Batavia IL: Flinn Scientific.
- Clark, M. (2011). Handbook of Textile and Industrial Dyeing: Principles, Processes and Types of Dyes. Elsevier. ISBN 978-0-85709-397-4.
- Clements, Allan; Dunn, Mike; et al. (2010). The Essential Chemical Industry. University of York: The Chemical Industry Education Centre.
- Needles, Howard L. (1981). Handbook of Textile Fibers, Dyes, and Finishes. Garland STPM Press. ISBN 978-0-8240-7046-5.