Kristin Bethea
H-18
2-10-14
The Science Of Tie Dying
Objective: Use the process of dying fabrics to illustrate chemical reactions, equilibrium, chemical bonding and pH.
Pre-Lab Questions
1. Where did the art of dying fibers originate? This originated in Asia and India no later than 2500b.c.
2. Originally, what type of substances were used to dye? The most natural dyes came from parts of plants like bark, berries, flowers, leaves and roots. Even today people use natural dyes like red cabbage and turmeric.
3. What are the fibers of the shirt made of? They are made of cellulose and cotton.
4. What chemical interaction is occurring when fibers are dyed? There is an ionic bond occurring because cotton fibers are already hollow, the dye fibers bond with the inside and outside of the fiber.
Video: Chemistry of natural dyes
Picking your design...
Lab Safety:
1.) Always wear safety glasses in the lab.
2.) Wear disposable plastic gloves and aprons.
3.) Don't get sloppy or squirt others with the dye solutions.
4.) Use caution handling the solutions. These are strong chemicals that can be harmful
Procedure:
The point of tie dying is to prevent the dye from reaching the fabric evenly. Any place the dye can’t reach will stay white, or a lighter color. You can accomplish this by folding the fabric, tying it with string, using rubber bands.
Step 1: With a permanent marker, write your name on the cloth you will be tie dying. There will be many other shirts in the lab during this activity; be sure yours is marked to avoid losing it.
Step 2: Soak your cloth in the hot water for about 5 minutes. Be sure you put it in the tub marked for your period.
Step 3: Put on a pair of gloves, remove your cloth from the soaking tub and wring out. Using the below diagrams, tie you cloth in one (or a combination of) the methods shown using string or rubber bands.
Step 4: Dye application. Apply the dye using the applicator bottles. Be aware that mixing will occur where the dyes come in contact with each other. Using complimentary colors (purple and yellows, blues and orange, or red and green) near each other usually produces a brownish black color. Also, the more dye you put on a given spot, the less white will remain on the final product.
Step 5: Place your dye-soaked item in a grocery or other plastic bag marked clearly with your name. No pooling of liquid should appear in the bag.
Step 6: After the cloth has soaked for at least 24 hours, open the bag, remove the item, and rinse it several times with warm water, before removing strings or rubber bands. Once it is rinsing clean, remove the ties and rinse several times again until it is rinsing clean. At this point, you can hang it to dry or place it in another bag to take home and wash.
The first time you wash it, place it alone in the washing machine with just a small squirt of dishwashing liquid like Dawn or Joy. Do not use laundry detergent.
Data:
1. Before dying the shirt we soaked it in warm water for five minutes. We then drained excess water and placed the damp shirt on a table. After that we proceeded onto making a pattern in the shirt.
2. To create my design I placed my shirt on the table and folded it in half. Then I pinched the middle of the shirt and began twirling it into a circle. I rubber banded the middle separately from the other sections. Once I placed all of my rubber bands on the shirt I began pouring dye on the shirt section by section. I dyed it in a purple, red, fuchsia, purple, red pattern.
3. Final results after 24 hours of drying my shirt:
Post Lab:
1. If you dyed a rainbow spiral on a shirt and then soaked it in a black dye bath, the result would be a black shirt with a rainbow spiral pattern why doesn't the entire shirt turn black?
Since the shirt already has a rainbow pattern the black dye would not turn the entire shirt black but make the colors in the spiral darker. Over dyeing with blacker adds depth and contrast to the rainbow spiral.
2. What is purpose of soaking the shirts in the hot water?
This helps the dye bond to the fibers of the shirt forming a bond. The heat in the water opens up boning sites in the cotton fibers allowing dye molecules to bond.
3. Why is 100% cotton the beat type of cloth to use with fiber reactive dyes?
Cotton is ideal for dying because the fibers are naturally hollow, and the dye molecules will form bonds on both the inside and outside of the fiber. If you put molecules of dye and cotton together, very little will happen until the atoms on the surfaces of the molecules are prepared for bonding.
4. What are some advantages of fiber reactive dyes?
Fiber-active dyes actually chemically (covalent) bond to the molecules of the fabric and can never be washed out. The dye molecules carry a “chromosphere”, which absorb varying spectrums of light, allowing only certain spectrums to reflect.
5. Explain how ionic bonding is used to dye the shirts in this lab.
This can be done by either increasing the temperature or the pH of the fiber and dye. In this lab, we will do the latter, increasing the pH by soaking the fabric in calcium carbonate, which causes the releases a H atom from the cellulose molecule. The removal of the H atom leaves the cellulose molecule with some atoms that do not have stable octets. As a result, the dye can bond to the cellulose molecule at the site of the removed H atom.
After the dye is applied, it is allowed to react in a desirable host environment for up to 24 hours. After this time, the bonding sites on the cellulose should be saturated with dye molecules. Excess dye molecules that have not bonded permanently are washed away using warm water rinse and a dye-carrying detergent.
Source: https://docs.google.com/presentation/d/1ceDthNrGkjcsIJyj_RzkZx7Nq6T0KUvDa71u3xO-dsM/edit#slide=id.p
