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Tropical Island Day Spa



Hot and sweaty from the tropical sun? What better way to recover than a luxurious day in a spa? Before you slather on that facemask and kick back in the sauna, you're going to have to figure out how to create the essentials for a day of pampering yourself! Discover the rough science behind what happens in a day spa.

The Challenges!



Add Scent and Texture to Your Soap

Soaps are made by boiling oils and fats with an alkali. Because this takes a long time and can be dangerous, we're going to use shredded olive oil soap as our base and add oils and flowers for scent and texture. For safety, ask the soap makers to tie back long hair and roll up their sleeves. Supervise young participants. To dry the soap quicker, place it in the sun or in a low oven for 15 minutes.

You'll need:

  • 2 saucepans, 1 large, 1 small
  • 1-lb. bar of olive oil soap
  • grater
  • plastic or glass droppers
  • a selection of herbal tea bags (chamomile, green tea, fruit flavors)
  • teapot or pitcher
  • essential oils such as lavender, geranium, vanilla, sweet almond oil (You can buy herbal teabags and essential oils in health food stores.)
  • dried flowers
  • oatmeal
  • tiny squares of candied fruit
  • a blunt object such as a butter knife
  • a cookie tray

What you do:
Shred a bar of soap using the grater. Place the large pan on a burner and fill the bottom with enough water to cover the bottom of the small pan that you place inside the large pan. Take care to make sure that the inside of the small pan stays completely dry, and that there's always water in the large pan. Place the grated soap in the small pan. Heat the large pan slowly on a medium flame till the soap melts. Add 1/4 of a cup of strong tea (that you have made) to the soap, mixing it in thoroughly. Spoon the soap mixture onto a cookie tray in six equal measures. Knead, or mill, each soap mixture with a knife. When the soap firms up, add your choice of essential oils using the droppers. Continue to knead until the soap is hard enough to pick up. Form it into a shape, then roll your bar of soap in dried flowers, oatmeal, or candied fruit. Allow the soap to dry completely before you use it.

What's going on?
Soap molecules have both fatty acid and salt-like properties. The latter allow the soap to dissolve in water, while the fatty acid properties allow the soap to dissolve dirt and oils. The combination of the two sets of properties gives soap its ability to dissolve grease in water.

For more information, see Rough Science episode 10: "Sustenance and Sayonara"



Create a Facial Mask

Whether your skin is oily or dry, it can benefit from a facial mask. Mixing eggs with mint and honey will make masks suited to oily skin; yogurt and cucumber will help rehydrate dry skin. Put slices of cucumber over your eyes while your mask is drying.

You'll need:

  • eggs, cucumbers, instant nonfat dried milk, plain yogurt, chamomile flowers, fresh mint, and honey
  • small bowls
  • whisks
  • graters

What you do:
In a small bowl, mix grated cucumber, yogurt, and dried milk with a whisk to create a moisturizing mask for dry skin. Mix egg, chamomile flowers, fresh mint, and honey with a wisk in another bowl to produce an astringent mask that will tighten pores in oily skin. Apply the mask that matcher your complexion to your face for 15 minutes, and then rinse it off with warm water.

What's going on?
The yogurt mask increases the flow of sebum (oil produced by glands in your skin) by causing your skin tissue to expand. The astringent (an agent that contracts tissue to reduce secretions) mask made from mint shrinks skin tissue and reduces the sebum flow.

For more information, see Rough Science episode 10: "Sustenance and Sayonara"



Make Lip Balm

Do your lips feel dry and burned from exposure to the tropical sun? What can you do to protect them? Let's make a scented lip balm using a mixture of beeswax and almond oil.

You'll need:

  • 1/4 cup sweet almond oil
  • 1/4 oz. beeswax
  • metal spoons
  • tropical fruit-flavored oils, such as mango, pineapple or coconut
  • small jars for lip balm
  • saucepan
  • small metal container
  • water

What you do:
Put a saucepan with a small amount of water on a low burner. Place the almond oil in a small metal container and place it in the water in the pan. When the oil warms up, add the beeswax to the container. Stir the mixture with a metal spoon until the beeswax is completely melted. Add drops of flavored oil and mix some more. Remove the mixture from the heat. Collect some in the spoon and put it in a cool place. When the spoonful hardens, test it with your finger. If your balm is too hard, add more oil. If it's too soft, add more beeswax. If the flavor is weak, add more drops of oil.

What's going on?
Lip balms and lip glosses contain oils and waxes that protect the lips and therefore act like a water repellent.

For more information, see Rough Science episode 10: "Sustenance and Sayonara"



Construct a Sundial

You have to watch how long you wear that facial mask. So let's make a timepiece for the spa.

You'll need:

  • sundial template
  • a magnetic compass
  • card stock
  • elastic string with metal ends
  • atlas

What you do:
Copy the sundial template onto card stock. Fold the tabs to an angle that corresponds to your latitude, as shown on an atlas. Then fold down both tabs to form the base of the sundial. Open your sundial to form a 90-degree angle and fold in the supporting tabs. To finish the dial, attach the elastic string through the holes at the top and bottom at the points where all the hour lines converge. This string is the gnomon (pronounced no-mun) and casts the shadow to indicate the time. To provide accurate time, the sundial (1) must be orientated with the gnomon pointing North/South; (2) must be located where a shadow will be cast by the gnomon most of the day. (Note: one can move the dial from window to window as the day progresses.) For greater accuracy, see the Equation of Time chart on the upper face of the sundial. A magnetic compass may be used to determine the North/South line. Because of the difference between magnetic North and true North, the sundial reading could be off by an hour or more. The variation will depend on the local difference between magnetic and true North.

What's going on?
Your location on Earth in relation to the sun determines the time where you are. Because the Earth rotates as it travels round the sun, the date is also very important. Compare 5 o'clock in the afternoon in July with the same time in December. Your watch or clock measures standard time. Your sundial records solar time, which is not the same. According to solar time, noon is when the sun is directly overhead. Even though noon in Boston, New York and Miami happens at the same moment in standard time, there would be noticeable differences if you measured noon at all three locations in solar time.

Activity adapted from Sun Sculpture & Sundial-Making Kit. New York Hall of Science, 2002. For information on making other sundials, see Liftoff to Space Exploration: A Space Sciences Project.

For more information, see Rough Science episode 7: "Mediterranean Mystery"



Make a Humidity Indicator

Is the tropical humidity giving you another "bad hair day"? Let's figure out how to determine how high the humidity is.

You'll need:

  • aluminum foil
  • newspaper
  • tape
  • pencil
  • scissors
  • empty spool

What you do:
Cut a strip of aluminum foil (10" x 4") and a strip of newspaper (10" x 10"). Tape the edges of the aluminum strip to the middle of the newspaper. Tape one end of the newspaper-aluminum strip to the top of the pencil and carefully and tightly wind the rest of it around the pencil. Place the pencil in the spool. If the weather is humid, the strip will unwind in the moist air. If the air becomes dry again, the strip will wind closed.

What's going on?
The paper expands when it absorbs moisture. The aluminum foil, a metal, doesn't absorb moisture. The tension between the two causes the strip to unwind and wind according to the amount of moisture in the air.

For more information, see Rough Science episode 2: "Bugs and Barometers"



Suggestions for other activities:

  • To make body paint, extract dye from plants, fruits, vegetables and flowers.
  • To make hair gel and aromatherapy shampoos, use plants.
  • To make henna tattoos, use henna (a natural dye that dates back to the ancient Egyptians) to produce a deep red/orange/brown color.
  • To make a perfume, blend natural oils.