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Vol. 93-4 CHEl\IISTRYEDITION' ©1993 Flinn Scientific, Inc.

Tie-Dyeing ~Chemistry Fun

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Penney SconzoWestminster SchoolAtlanta, Georgia

The art of dyeing probably originated inIndia or China no later than 2500 BC. Mostnatural dyes came from parts of plants suchas the bark, berries, flowers, leaves, androots. Because these dyes did not have astrong attraction for the fibers being dyed, aprocess known as mordantinq was used toimprove colorfastness. To react with acidicdyes, fibers were treated with basic ormetallic mordants which might includesolutions of aluminum, copper, iron, orchromium salts. Compounds formed by thedye and the mordant, called lakes, pre-vented the colors from washing out andmade the color longer lasting. Such naturaldyes became less and less important as syn-thetic dyes that produced brighter colorswere developed. Today, Iogwood black is theonly natural dye widely used.

In 1856, William Henry Perkin began thesynthetic organic chemical industry byaccidentally discovering the purple dye,mauveine, when he tried to produce quininefrom aniline. The synthetic dyeswere knownas coal tar dyes because the six-memberedring structures of carbon atoms were all de-rived from coal tar. Congo Red was the firstdye discovered with so great an affinity forcellulose that a mordant was not required.

About 100years after Perkin's first discov-ery, fiber-reactive dyes capable of formingcovalent linkages with the fiber were dis-covered. A fiber-reactive dye is washfast.During dyeing, dye molecules must diffusefrom the aqueous solution and into thefibers. Fibers such as cotton absorb waterreadily and are said to be hydrophilic, whilefibers such as polyester absorb water withdifficulty and are described as hydrophobic.Dyeability is influenced if a fiber can some-how carry an ionic charge and better inter-act with oppositely charged colored ions. To

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dye cellulose, a reactive dye must combinewith the hydroxyl groups in the fiber.

Tie dyeing is one of the oldest methods ofprinting designs on fabrics. Typically, partsof the fabric are bunched together in adesign and knotted or tied together withstring. Tied sections are protected fromabsorbing the dye and patterns are created.

Related Chemical Concepts:Dyes, chrornophores, affinity (hydropho-

bic/hydrophilic). covalent bonding vs.adsorbtion, electrolyte concentration, equi-librium, kinetics, reaction rates (tempera-ture effects, concentration effects), pH

Materials Needed and PreparationInstructions• T-shirts, 100% cotton, PFD (prepared for

dyeing)If you buy T-shirts that are not preparedfor dyeing, they must be pre-washed inhot water with 2 tablespoons of a milddetergent like Joy®, Dawn", Ivory", etc.Do not use a detergent with phosphatesor chlorines. Dry shirts on the hot cycleto remove spinning lubricants or othersurface additives.

• Sodium carbonate activator solutionFor a class of 30 students you will needapproximately 8 liters of sodium carbon-ate activator solution. To prepare thissolution, mix 250 grams of sodium car-bonate anhydrous into 8 liters of distilledwater and stir.

• Urea solutionFor a class' of 30 students you will needapproximately 8 liters of Urea solution.To prepare this solution, mix 650 gramsof urea into 8 liters of water and stir.This solution can be stored if it is notmixed with the reactive dye. Ureaincreases the solubility of the heavyshades of reactive dyes.

• Reactive DyesPlace a small amount of cold water in abeaker and add 4 to 6 teaspoons (12-18grams) of the reactive dye you haveselected. Mix until lumps are removedand all dye is moistened. Add urea solu-tion (as described above) to make a totalof one liter of dye solution.The amount of reactive dye is not specificas it depends on how strong you want thecolors to be. Colors like yellow will needmore dye. Remember some of the dyewill wash out when the T-shirt is washedin hot water, so make the color darkerthan you want as an end productEach student will require about one cupof dye solution. For a class of 30 stu-dents, prepare a total of 2 liters <5freac- .tive dye solution for each color you wantto use.Reactive dyes should be stored at roomtemperature.If kept dry, reactive dyes have a shelf lifeof two years.

• Plastic bucket• Plastic drop cloth

(Continued on page 2)

VoL93-4 CHEMISTRY EDITION

TieDyeing-Continued

• Rubber bands! size 33 (3 1I2"Lx 1/8"W).Jumbo, Beral-type pipets, 15 ml bulb

capacity .

• Beakers, 1000 ml• Oven racks or sturdy plastic coat hangers

interlocked between slats of wood

• Rubber gloves• Ziplocksbags or small trash bags• Newspaper

Procedure:1. Fill the plastic bucket with 8 liters of

sodium carbonate activator solution.Soak the T-shirts in the sodium carbon-ate activator solution for a minimum of20 minutes. The ionization of celluloseincreases with increasing alkalinity ofthe solution and above pH 8 there is anadequate number of ionized hydroxylgroups in the fiber for most dyeing pur-poses. Soaking the T-shirts for 2 hourswill maximize the number of possiblebonding sites. After the T-shirt hassoaked, wring the T-shirt out over theplastic bucket.

The sodium carbonate activator solutionis very basic so be sure to wear rubbergloves when placing shirts in the solu-tion and when the shirt is wrung out atthe end of the activation period.

2. Shirts are now ready to fold and tie. Aspiral pattern is created by laying theshirt flat on a surface protected by aclean dropcloth. The shirt is held withthe thumb and fingers at the point wherethe center of the spiral will be located.Use a twisting motion to coil the shirtand use your other hand to bring theloose ends of the shirt into the circle (seeFigure 1). Take four rubber bands andslide them around the shirt so they inter-sect at the center where the twist began(see Figure 2). You now have whatappears to look like a "pie" cut into eightpieces. The bound shirt can be turnedover and dyed on both sides. We selectedthis type of folding pattern because it isthe easiest to do and the entire tie-dye-ing process can be completed in a 50-minute lab period. Students also like thispattern the best.

Figure 2

Hint This should be' done in an area sep-arate from the dyeing area to preventshirts frompickingup dye by mistake.

3. Dyeing can be done on oven racks placedover sinks or on racks with newspaperunderneath to absorb' excess dye. After ashirt is placed on a clean rack, dyes canbe applied using jumbo Beral-typepipets. Apply the dye to one side of theshirt by slowly squirting the reactive dyesolution onto each section of the shirt. Abeautiful design can be made by dyeingeach section of the shirt a .differentcolor. Once you are done dyeing one sideof the shirt, turn the shirt over andrepeat the dyeing process. Shirts shoulddrain for 15 minutes if possible.Students tend to use a lot of dye andthere is a lot of dripping so be prepared.

Hint: Fewer beakers of dye and morepipets work best. Too many beakers taketoo long to clean up and reorganizebetween classes. Shirts can pick up somedye by mistake, but students will beapplying so much dye that it probablywill not matter. Clean work areas willminimize problems.

4. Place shirts in a plastic Ziplock" bag orsmall trash bag and close to keep theshirt moist. Drying will prevent the reac-tive dyes from fully reacting. Most colorswill have completely reacted after 4hours but less reactive colors such asgreen and turquoise will take as long as24 hours. Be patient. Let the dyes reactcompletely.

5. At home, rinse the shirt in warm water(75-900F) in order to remove the unre-acted dye and the sodium carbonate acti-vator. Change the water and continue torinse. Repeat until the water remainsclear and the shirt does not feel slippery.

Set the washing machine on the HOTwater setting and wash as many as 10shirts at one time in 2 tablespoons of thepre-wash, such as Joy® or Dawn" dish-soap. Dry shirts on the hottest dryer set-ting. The reactive dye is washfast so it isnow safe to wash with other clothes usingnormal detergents. The reactive center onthe dyes is a dichloro-triazinyl group sodo not use bleaches on the shirt.

6. Now be creative! Try other patterns forfolding. Dye labcoats, socks, tennis shoes,

etc. This makes a great lab to do beforethe Christmas holidays. Students canmake personalized gifts that are afford-able. Use this activity as a fund raiser forthe science club at your school.

Safety Precautions:Students should wear old clothes and

shoes. Reactive dyes are "wash fast." Oncethe reactive dye makes contact with clothesit will not wash out.

Do not let the students get sloppy.Students should not squirt each other withfilled pipets of reactive dye solution.

Students should wear appropriate protec-tive clothing, e.g., chemical splash goggles,disposable plastic gloves and chemical-resistant aprons.

Hands may become stained from the reac-tive dye. It is not easily washed off and willtake about two days for the dye to wear offyour hands,

Sodium carbonate activator solution isvery basic. Be sure to wear rubber or plasticgloves when placing the T-shirts in solutionand when the shirt is wrung out at the endof the activation period.

Disposal:All of the chemical solutions and reactive

dyes may be disposed of according to FlinnSuggested Disposal Method #26b. Consultyour current Flinn Chemical Catalog/Reference Manual.

Literature Cited:American Association of Textile Chemists

and Colorists (MTCC). Dyeing Primer. Aseries of short papers on the Fundamentalsof Dyeing. P.O. Box 12215, ResearchTriangle Park, NC 27709.

Vickerstaff, T. "Theoretical Principles ofDyeing with Reactive Dyes." ProcionDyestuffin Textile Dyeing, 1962, pp. 17-40.

Special thanks to Gerald Blackstone,Eastchester High School, Eastchester, NYand Elenore Grow, Horizon High School,Brighton, CO for showing me how to tie-dye.

Ordering information for Flinn's Tie-Dyeing-Chemistry Fun Kit is listed onpage 7 of this Flinn Fax. Individual tie-dyeing supplies may be found below.

AP8701Z Pipets, Jumbo, Beral-type $ 9.5015 ml capacity, pkgJ120

AP8702Z Urea, 650 g 8.45

AP8703Z Sodium carbonate, 250 g 5.40

AP8704Z Reactive Dye, Yellow, 8.5045 grams

AP8705Z Reactive Dye, Red, 8.2545 grams

AP8706Z Reactive Dye, Blue, 10.1045 grams

AP8707Z Reactive Dye, Green, 11.2545 grams