Hand cream is an example of an emulsion.
Liquids that don't mix, like oil and water, are called immiscible. An emulsion is a stable mixture of two immiscible liquids. You make an emulsion by breaking one liquid up into tiny droplets that are suspended evenly throughout the other liquid. In some cases, you can use an emulsifier to help with this process. Familiar examples of emulsions are hand creams and sauces like mayonnaise. You can learn about emulsions by making your own.
Instructions
Basic Emulsion Experiment
1. Fill a clean, empty bottle with water.
2. Add some oil to the bottle of water and screw the lid firmly in place. Shake the bottle vigorously so that the oil and water form a cloudy mixture.
3. Leave the bottle to stand for a while. Observe how the oil separates from the water and floats to the surface.
4. Add a few drops of dish soap to the bottle. Shake it up again.
5. Leave the bottle to stand for a while. Notice that the oil and water no longer separate but remain mixed. The oil has broken up into droplets that are held in the water by the emulsifying action of the soap.
Mayonnaise (Egg Yolk Emulsion)
6. Break two large eggs. Separate the yolks from the whites and place the yolks in a mixing bowl. Beat the yolks with an electric mixer or hand whisk.
7. Add 2 tsps. of mustard or 1 tsp. of mustard powder. Whisk the mustard into the beaten yolks.
8. Measure out 1 1/8 cups of olive oil or vegetable oil. Add the oil slowly, a drop at a time, to the egg yolk mixture, whisking constantly. If you add the oil too fast the emulsion will fail. After approximately one quarter of the oil has been added, the mayonnaise will begin to thicken. After this point, you can add the oil in larger amounts. Add the oil until half of it is mixed in, whisking continuously.
9. Measure 1 or 2 tbsps. of white wine vinegar and add to the mixture. Continue to add the oil slowly until it is all beaten into the mayonnaise. The egg yolks have now formed an emulsion with the oil, with lecithin from the yolks acting as the emulsifier.
Simple Hand Cream
10. Measure 5 tbsps. of olive oil and 3 tbsps. of beeswax into the double boiler. Fill the outer part of the boiler with water. Place the double boiler on a stovetop or hot plate. Melt the oil and wax together over a low heat. Mix well using a heatproof spatula or spoon.
11. Measure 1 tsp. water. Add to the oil and wax mixture along with a pinch of borax. Mix well.
12. Add a few drops of essential oil to the cream and blend well with the other ingredients. Remove the cream from the heat. Pour the cream into a small, clean jar or pot. The borax has caused the oils, wax and water to form an emulsion. You can now use this emulsion as a hand cream.
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