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This week's LabZone activity
March 17, 2004
Lipstick
Lipstick, as we know it today, came into use just before World War I. All lipsticks, from then to the present, contain an oil-wax base and two kinds of coloring agents, dyes and pigments. A dye dissolves in the base and will stain the lips. Dyes are the basis for long-lasting lipsticks, which were popular in the 1950s and came back into style in the 1980s. Pigments do not dissolve but are suspended in a base. Pigments are not absorbed by the skin but stick to its surface. A pigment's ability to color something depends on how densely and evenly it is distributed in the base, and this depends on how finely it is ground. Pigments that are used in cosmetics and paints are ground in mills. For this reason, they are called milled pigments.
Milled pigments that are already suspended in a wax base are found in crayons. You can make your own lip gloss out of a crayon.
Materials and Equipment
- beeswax (a beeswax candle is the source that's easiest to find)
- mineral oil
- 3 5/8 inch x 5/16 inch nontoxic crayon
- heat resistant custard cup
- plastic bag
- hammer
- paper toweling
- small saucepan
- knife
- spoon for stirring
Procedure
Put about one teaspoon beeswax in the custard cup. This is a 1/2 inch slice of a beeswax candle one inch in diameter. Add three tablespoons mineral oil to the cup. Put the crayon in a plastic bag and smash it with a hammer. This makes it easy to remove the paper wrapper. Put the smashed crayon in the cup.
Set the custard cup in the small saucepan that contains enough water to reach a level of about 1 1/2 inches up the side of the custard cup. Check with an adult before you use the stove. Put the setup over a medium heat. Heat, stirring occasionally, until the waxes are melted and the color is evenly spread throughout the liquid. Turn off the heat and allow your lip gloss to cool for five to ten minutes.
Observations and Suggestions
When you apply your lip gloss to the back of your hand, it will look quite shiny. This is due to the oil in the base. The beeswax stiffens the mixture and holds the pigment. The combination of wax and oil, which mix evenly with each other when hot, produces a base that is still soft enough to spread easily. The milled pigments are carried along by the base.
You can use the custard cup in a water bath to make recycled lipsticks out of old lipsticks your mother may have around the house. As always, check with an adult before using the stove. Put the old lipsticks in the cup, melt them in the water bath, mix thoroughly and create new shades.
When you test your creations, try them out on the back of your hand. If you can see through them, they are translucent or transparent. If they make a strong color that you can't see through, they are opaque. If they have a "frosted" look they probably contain ground fish scales or ground synthetic pearls.
Reprinted with permission from The Secret Life of Cosmetics: A Science Experiment Book by Vicki Cobb. Text © 1985 by Vicki Cobb (www.vickicobb.com). Published by HarperCollins.
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