Name________________ Worksheet on Dyes (From Chem Matters)

1. Dyes have been used for a long time. The Neanderthal coated their dead

with red ochre which was really____________.(rust). Cave paintings used

_________and_________ iron _________, black_________and white

________. Humans got their coloring agents from______and________until

weaving was invented. What is the difference between a dye and a

pigment?

2. One of the most important animal dyes came from the __________which

formed a __________color. The dye was extracted by ____________the

shellfish and boiling them in _________water for _______days. Cloth was

dipped, placed in the sun, and the color changed to ___________then to

__________. In the beginning only the ________could wear it. Later dyes

were formed from_________and it was a _________color. Cochineal was

an________and used until 1954 to dye___________________________.

3. Vegetable dyes can be made from plants. The three most important

were ___________, ____________, and ____________. Madder is a

_______color and the chemical it contains is ____________. Woad is a

_______color and contains_________as its chemical.

4. What are chromophores? (Look on left of page 6)

When the light of certain colors strikes the chromophores, _________are

energized and the light is__________. A good dye must also be_________

so the solution can penetrate the fabric. Once in the fibers it must become

__________or attach itself to the fibers, so it does not wash out. The

dyes that we will use for tie dye are fiber reactive. This means that the dye

molecules react with the cellulose (cotton) molecules in the shirt.

5. Saxon green was a mixture of __________and __________. Indigo is

much richer in the __________molecule. It was called the _________and

believed to harm both the __________and its__________. The anti-indigo

lobby kept the plant out for ________years. Finally it was chosen for the

British naval uniform and it gave the world_________forever after.

Today indigo has been largely replaced by other blues EXCEPT it is till used

for dyeing __________.

6. A mordant (page 7) is a _______________. It is usually a ________ion

that attaches to both the _______and the _________and forms a_______

between them. Most mordants are salts of _______________________-

_________________. Some mordants change the _________. Alizarin

(red) turns____________when reacted with _________, or ________with

calcium, and __________with__________.

7. Indigo is not soluble in water so is applied by _____________________.

Indigo used to be treated by _________but today they use___________.

The cloth is soaked, then___________by hanging it in the air. Oxygen

____________ the indigo back to the _________form which is ________

and difficult to wash out.

8. A college student named _________made the first synthetic dye named

_________as it was a purplish color. In the beginning the ________ were

the leaders in the dye industry, but soon the _______________took over.

9. Today more than _____________synthetic dyes are available.

10. Levi Strauss started dyeing___________from tents with _______to

make the first_________. The heavy gold nuggets ripped out the pockets,

so Levi reinforced them with ____________. The word denim came from

_________________. Nowadays in denim mills, _________is unwound and

passed quickly through___________(yellow) then exposed to air where it

turns_______________. This process is repeated as many times as

________until the color is jeans blue. The back side of denim is_________

blue and _________white. Roll up your jeans and take a look. Jeans get

better with age as the color gets lights and softer. Right? However, stone

washing makes them soft to begin with.

The dyes that you will use to tie dye are called PROCION MX and have been

around since the 1950's. They are fiber reactive so have a chemical reaction

with the cellulose (cotton) in your t-shirt. They became very popular in

the 60's and were worn by many hippies and young people. However, several

times since then tie dye has come back in style. Enjoy your tie dye!