Pre-lab Questions:
1. Where did the art of dying fibers originate?
The art of dying fibers originated in India or China no later than 2500 B.C.
2. Originally, what type of substances were used to dye?
Red cabbage, indigo and cochineal were used to dye fibers.
3. What are the fibers of the shirt made of?
Cotton, which is the type of fiber I used for my experiment, is composed of cellulose fibers.
4. What chemical interaction is occurring when the fibers are dyed?
The fibers, which are cellulose, consist of hydrogen and oxygen atoms. When a base, such as a carbonate base, is applied to the fibers, the base strips the cellulose of its hydrogen atoms, leaving a potential negative bonding site for the dye. When the dye-which has a chloride ion attached to it-is applied to the fibers, it's chloride ion goes away, and the negatively charged cellulose and positively charged dye are attracted to each other due to their opposite charges, meaning the dye is bonded to the thread itself.
Data:
1. Write down a synopsis of what occurred before dying the shirt.
Before dying my shirt, I tied it into a knot and secured it with a green rubber band to assure that my shirt would not be lost in the bucket with all of my other classmates' shirts. Then, I let my shirt soak for about five minutes in warm water, wrung it out, and placed it onto my table which was protected with a plastic sheet. Finally, I began tying and securing my shirt with rubber bands into the form in which was necessary for my design and I was ready to dye.
2. Explain the method used to dye your shirt-pattern tying method.
First, I pinched the the fabric in the center of my shirt and grabbed a reasonable amount of fabric to dye, and tied a rubber band around it. Then, I continued to section off pieces of fabric, placing rubber bands at my desired end points, and making the rest of the sections look identical to my first one. It eventually looked like straight chain with sectioned off chunks.
3. After the shirt sat for 24 hours, describe the pattern of the shirt-picture if possible.
The pattern on my shirt looked like a bunch of colored rings surrounding one another. It began with a solid red spot in the center, surrounded by an orange ring, a yellow ring, a white ring and finally a blue ring. The pattern I was mimicking was the bulls-eye pattern.
Post Lab Questions:
1. If you dyed a rainbow spiral on a shirt and then soaked it into a black dye bath, the result would be a black shirt with a rainbow spiral pattern. Why doesn't the entire shirt dye black?
Once a spot on the shirt is dyed, the dye is permanently there. Any dye applied over the original dye will not be translated. Nevertheless, while arranging a shirt into the form for your desired pattern, wherever rubber bands are placed will often not dye since the rubber bands are covering certain spots on the shirt. This means when the rubber bands are removed, those spots can still be dyed, which explains why the shirt would be black with a rainbow spiral after soaking it in a black dye bath.
2. What is the purpose of soaking the shirts in the hot water for 5 minutes?
Very little will happen to the shirts until the atoms on the surface of the cellulose molecules (the cotton fibers) are prepared for bonding. Soaking the shirts in hot water prepares the shirt for bonding by increasing the shirts temperature and acting as a base.
3. Why is 100% cotton the best 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.
4. What are the advantages of fiber reactive dyes?
Fiber reactive dyes actually chemically (covalent) bond to the molecules of the fabric and can never be washed out, unlike other dyes which only stain the cloth and wash out a little each time the shirt is laundered.
5. Explain how ionic bonding is used to dye the shirts in this lab.
Ionic bonding is the electrostatic attraction between oppositely charged ions. The oppositely charged ions in this case are the dye, with a positive charge, and the cellulose, with a negative charge. This bond is formed when a base is applied to the fabric (cellulose) stripping it of its hydrogen atoms, leaving its oxygen atoms with a negative charge and a potential bonding site. When the dye is applied to the fabric, the dye loses its chloride ion, leaving it positively charged and able to bond with the negatively charged oxygen atoms in the fabric.
Lab Safety Rules:
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 harmfulProcedure: 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.
Materials Used:
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