• Sodium carbonate activator solution For a class of 30 students you will need approximately 8 liters ofsodium carbon -ate activator solution.. Fill the plastic bucket with 8 liters of s
Trang 1FLINN SCIENTIFIC INC.
P.O BOX 219 • BATAVIA, ILLINOIS 60510 • 800/452-1261
o
Penney Sconzo
Westminster School
Atlanta, Georgia
The art of dyeing pro ably originated in
IndiaorChina no later than2 50 0BC.Most
natural dyes camefrom parts ofplants such
as the bark, berries, flowers, le ves, and
roots Because these dyes did not have a
strong atraction for thefibersbein dyed, a
process known asm o rd anti nq was used to
improve colorfastness Toreactwih acidic
dyes, fibers were treated with basic or
metallic mordants which might include
solutions of aluminum, copper, iron, or
chromium salts Compounds formed by the
dye and the mordant, called la kes ,
pre-vented the colors from washing out and
madethecolor longer lasting Such natural
dyes became less and less important as
syn-thetic dyes that produced brig ter colors
were developed Today,Iogwood black is the
only natural dye widely used
In 1856 ,William Henry Perkin began the
synthetic organic chemical industry by
accidentally discovering the purple d e,
mauveine, when hetried toproduce quinine
fromaniline.Thesyntheticdyes were known
as coal tar dyes because the six-membered
ring structures ofcarbon atomswere alld
e-rivedfrom coal tar Co goRedwas the first
dyediscovered with so gre t an affinity for
cellulose that a mordant was not requied
About 100years after Perkin's firstdiscov
-ery, fiber eactive dyes capable of formin
covalent linkages with the fiber were d
is-covered Afiber-reactive dye iswashfast
During dyeing, d e molecules must diffuse
from the aqueous solutio and into the
fibers Fibers such as cotton absorb water
readily and are said to be hydrophilic, while
fibers such as polyester absorb water with
difficulty and are described as hydrophobic
Dyeability is influenced if a fiber can some
-how carry an ionic charge and better inte
r-act with oppositely charged colored ions.To
o
d e cellulose, a reactive dyemust combine
with the h droxylgroups in the fiber Tie dyeing is one of the oldest metho s of
printing desig s on fabrics.Typically,parts
of the fabric are bunched together in a
desig and knotted or tied together with
sting Tied sections are protected fom absorbin the d e and patterns are created
Related Che mi cal Concepts: Dyes, chrornophores, affinity (hydro ho
-bic/h drophilic) covalent bonding vs
adsorbtio , electrolyte concentration, equ
i-librium, kinetics, reactio rates (temp
era-ture effects,concentraton effects),pH Materials Needed and Preparation
Instructions
• T-shirts, 100 %cotton, PFD (prepared for
d eing)
If you buyT-shirts that are not prepared
for dyeing, they must be pre-washed in hot water wih 2tablespoons of a mild
detergent likeJoy®, Dawn", Ivory", etc
Donot use adetergent with phosphates
or chlorines Dry shirts on the h t cycle
to remove spinning lubricants or other
surface additives
• Sodium carbonate activator solution
For a class of 30 students you will need
approximately 8 liters ofsodium carbon
-ate activator solution To prepare this
solution, mix 250 grams ofsodium c
ar-b nate anhydrous into 8lite of distilled
water and sti
• Ureasolutio
For a clas ' of30 students youwillneed approximately 8 liters of Urea solutio
To prepare this solutio , mix65 0grams
of urea into 8 liters of water and stir
This solution can be stored if it is not
mixed with the reactive d e Urea increases the solubility of the heavy
shades of reactive dyes
• ReactveDyes
Place a small amount of cold water in a
beaker and add 4 to 6 teaspoons (12-18
grams) of the reactive dye you have
selected Mixuntil lumps are removed
and all dye is moistened Add urea
solu-tion (asdescribed above) to make a total
ofone liter of dye solutio The amount of reactivedye is not specific
asitdepends on howstron y u want the
colors to be.Colors like yellow will need
more dye Remember some of the dye
willwash outwhen theT-shirt is washed
in hot water, so make the color darker than you want as an end product
Each student will require about one cup
of dye solution For a class of 30 stu
-dents, prepare a total of 2 liters <5freac-
tve dyesolution for each color you want
to use
Reactive dyes should be stored at room
temperature
I kept dry, reactivedyes havea shelf life
oftwo ye rs
• Plastic bucket
• Plastic dropcloth
(Con t nu e d on pag e 2 )
Trang 2VoL93-4 CHEMISTRY EDITION
TieDyeing-Continued
• Rubber bands! size 33 (3 1I2"L x 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
• 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 of
20 minutes The ionization of cellulose
increases with increasing alkalinity of
the solution and above pH 8 there is an
adequate number of ionized hydroxyl
groups in the fiber for most dyeing
pur-poses Soaking the T-shirts for 2 hours
will maximize the number of possible
bonding sites After the T-shirt has
soaked, wring the T-shirt out over the
plastic bucket
The sodium carbonate activator solution
is very basic so be sure to wear rubber
gloves when placing shirts in the
solu-tion and when the shirt is wrung out at
the end of the activation period
2 Shirts are now ready to fold and tie A
spiral pattern is created by laying the
shirt flat on a surface protected by a
clean dropcloth The shirt is held with
the thumb and fingers at the point where
the center of the spiral will be located
Use a twisting motion to coil the shirt
and use your other hand to bring the
loose ends of the shirt into the circle (see
Figure 1) Take four rubber bands and
slide them around the shirt so they
inter-sect at the center where the twist began
(see Figure 2) You now have what
appears to look like a "pie" cut into eight
pieces The bound shirt can be turned
over and dyed on both sides.We selected
this type of folding pattern because it is
the easiest to do and the entire
tie-dye-ing process can be completed in a
50-minute lab period Students also like this
pattern the best
Figure 2 Hint This should be'done in an area sep-arate from the dyeing area to prevent shirts frompickingup dye by mistake
3 Dyeing can be done on oven racks placed over sinks or on racks with newspaper underneath to absorb'excess dye After a shirt is placed on a clean rack, dyes can
be applied using jumbo Beral-type pipets Apply the dye to one side of the shirt by slowly squirting the reactive dye solution onto each section of the shirt A beautiful design can be made by dyeing each section of the shirt a.different color Once you are done dyeing one side
of the shirt, turn the shirt over and repeat the dyeing process Shirts should drain for 15 minutes if possible
Students tend to use a lot of dye and there is a lot of dripping so be prepared
Hint: Fewer beakers of dye and more pipets work best Too many beakers take too long to clean up and reorganize between classes Shirts can pick up some dye by mistake, but students will be applying so much dye that it probably will not matter Clean work areas will minimize problems
4 Place shirts in a plastic Ziplock" bag or small trash bag and close to keep the shirt moist Drying will prevent the
reac-tive dyes from fully reacting Most colors will have completely reacted after 4
hours but less reactive colors such as green and turquoise will take as long as
24 hours Be patient Let the dyes react completely
5 At home, rinse the shirt inwarm water (75-900F) in order to remove the unre-acted dye and the sodium carbonate
acti-vator Change thewater and continue to rinse Repeat until the water remains clear and the shirt does not feel slippery
Set the washing machine on the HOT
water setting and wash as many as 10 shirts at one time in 2 tablespoons of the pre-wash, such as Joy®or Dawn " dish-soap Dryshirts on the hottest dryer set-ting The reactive dye is washfast soit is now safe to washwith other clothes using normal detergents The reactive center on the dyes is a dichloro-triazinyl group so
do not use bleaches on the shirt
6. Now be creative! Try other patterns for folding Dye labcoats,socks, tennis shoes,
etc This makes a great lab to do before the Christmas holidays Students can make personalized gifts that are afford-able Use this activity as a fund raiser for the science club at your school
Safety Precautions:
Students should wear old clothes and shoes Reactive dyes are "wash fast." Once the reactive dye makes contact with clothes
it will not wash out
Do not let the students get sloppy Students should not squirt each other with filled 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 will take about two days for the dye to wear off your hands,
Sodium carbonate activator solution is very basic Be sure to wear rubber or plastic gloves when placing the T-shirts in solution and when the shirt is wrung out at the end
of the activation period
Disposal:
All of the chemical solutions and reactive dyes may be disposed of according to Flinn Suggested Disposal Method #26b Consult your current Flinn Chemical Catalog/ Reference Manual
Literature Cited:
American Association of Textile Chemists
and Colorists (MTCC) Dyeing Primer. A series of short papers on the Fundamentals
of Dyeing P.O Box 12215, Research Triangle Park, NC 27709
Vickerstaff, T "Theoretical Principles of Dyeing with Reactive Dyes." Procion
Dyestuffin Textile Dyeing, 1962, pp 17-40.
Special thanks to Gerald Blackstone, Eastchester High School, Eastchester, NY and 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 on page 7 of this Flinn Fax Individual tie-dyeing supplies may be found below
45 grams
45 grams
45 grams
45 grams