Water -

A Mighty Molecule

Natural and Synthetic Dyes

Mindful Minute

If thoughts come up, let them pass by like clouds. Don’t analyze of judge them. They do not change the sky.

Homework

Work on notebooks. Due on ???

Natural & Synthetic Dyes - P. 113 (Cont’ed)

STAPLE the 3 swatches of fabric into your ISN. Label them. Annotate. Compare wool to cotton: Do they look the same? If not, how are they different.

Directions: Take a few minutes to silently write what properties a dye should have.

A good dye should:

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- soluble or insoluble? (soluble = able to dissolve in water)

Adherence of Dyes

A good dye must:

• Must attach to fiber.
• Must keep its color (colorfast) when washed or exposed to sunlight (lightfast).

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Synthetic fibers are able to take synthetic dyes but don’t take natural dyes well.

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• Almost all cultures have significantly important dyes, such as indigo in Japan.
• In 1856 William Perkin, an English chemist, created a synthetic dye. Synthetic dyes are: � - colorfast and lightfast� - bind more effectively to the fabrics� - consistent color
• Now: Increased interest in natural dyes with people concerned about the environment and reconnecting with their own heritage.

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History of Dyes

A dress dyed with mauveine, the first synthetic dye.

Electromagnetic Radiation�

Light is a form of energy that travels through space like a wave and is characterized by its wavelength.

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Only certain wavelengths of light can be detected by the human eye.

Some Natural Dyes

Although many plant parts are colored, the components of some of these parts decompose quickly and do not make for good dyes. Some do not bind well to the fibers.

Indigo

Indigo (Indigofera tinctoria, Fabaceae) has been one of the most important dyes. Used 6000 years ago in China to modern times.

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• Indigo became an important item of trade between India and other parts of the world by 300 B.C.
• Indigo was an early crop in colonial South Carolina. South Carolina indigo was considered excellent, but as the economics were not too good, it was replaced by rice.
• Synthetic indigo was produced in 1897.

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Blue jeans dyed with synthetic indigo.

Carolina Gold. This was a premier rice in Europe and Asia in the 1800s. It almost went extinct!

Madder

• Madder (Rubia tinctoria, Rubiaceae) has been used since ancient times.
• Used to color the colonial British soldiers = “Red Coats”
• Used to color Egyptian mummy wrappings. �

It matters how you pretreat natural fibers. The outcome can vary greatly and surprise you!

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Henna (Lawsonia inermis)

By 3000 B.C., Greek women used henna to dye their hair. The leaves are ground into a paste that has easily attaches to proteins in hair.

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Litmus dye comes from the lichen Rochella tinctoria. This pigment helps us tell if it’s an acid or base. ��Other plants also serve as acid-base indicators, such as red cabbage & hydrangeas.

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Natural Dyes in Science: pH

Hydrangeas will also change color depending on if the soil is acidic or basic.