By JEANNIE WILEY WOLF
There are few things as relaxing as watching colorful soap bubbles sail off in the breeze on a warm summer afternoon.
Blowing bubbles isn’t a recent pastime. Illustrations of soap bubbles can be found in Western European art as early as the Renaissance, according to information on the University of Miami’s website. In a French woodcut dating from 1587, figures can be seen blowing and chasing bubbles in a courtyard.
Scientists and mathematicians have also studied soap bubbles for hundreds of years, the website said. During the 17th century, Sir Isaac Newton used soap bubbles to study the interference of light. He also devised a method of measuring their thickness and concluded that at their thinnest point, soap bubbles measure 1/2,500,000 of an inch thick.
At about the same time, the French artist Jacques Stella designed the illustrations for his book, “Les Jeux et Plaisirs de L’enfance” (Games and Pastimes of Childhood). First published in 1657, the book includes an illustration of children playing with soap bubbles as well as the following poem:
“Here children scrap and suffer troubles
For nothing greater than soap bubbles,
As though for guineas, pounds and pence.
And yet we see among adults
The same ado, the same results
For things of much less consequence.”
What is a bubble?
Jeffrey Frye, dean of the college of sciences at the University of Findlay, said there’s a lot of science behind these soapy suds, despite their magical characteristics.
“To make a bubble, you need soap and water and air,” he said. “It’s not magic, it’s science.”
In simplistic terms, bubbles are pockets of soap and water filled with air. The film that makes the bubble has several layers, said Frye. A thin layer of water is sandwiched between two layers of soap molecules. Each soap molecule is oriented so that its polar (hydrophilic) head faces the water, while its hydrophobic hydrocarbon tail extends away from the water layer, he said.
“These types of molecules are very interesting because when you put them in water, that polar part wants to interact with the water. The nonpolar part doesn’t want to interact with the water,” he said. “So what happens is just like when you pour oil and water together and they eventually separate.”
Why is it round?
Frye said no matter what shape a bubble has initially, it will typically become a sphere. A sphere is the shape that minimizes the surface area of the structure, which makes it the shape that requires the least energy to achieve.
“Wands can be any shape, but the bubbles will always form a sphere,” he said.
As the air escapes, the bubble tends to shrink until it collapses. However, gravity drains the water from the top of the bubble. When the film becomes too thin to support the heavier lower portion, the bubble bursts.
Why do they pop?
All soap bubbles pop after a while because the layer of water can still escape into the atmosphere.
“Water goes through that natural process of evaporation, … so when the water evaporates, these groups get too close to one another and they pop, so the bubble pops,” said Frye.
“You can also take your finger and pop it because then you disrupt that layer,” he said.
What happens when bubbles meet?
When two bubbles meet, they join together to minimize their surface area. If bubbles of the same size meet, the wall that separates them will be flat. If bubbles that are different sizes meet, the smaller bubble will bulge into the large bubble.
Frye said we don’t tend to think of physics working at that small of a level, “but that’s where all those forces that are acting on those bubbles come into play.”
Why are there colors in bubbles?
The iridescent colors in a soap bubble are produced by the refraction of light, said Frye.
Similar to the way we see the colors in a rainbow or an oil slick, the colors in a bubble are seen through the reflection and the refraction of light waves off the inner and outer surfaces of the bubble wall, he said.
More importantly, perhaps, is the fun factor when it comes to bubbles. Michelle Rumschlag, a naturalist who is also in charge of programming for the Hancock Park District, said employees have been offering a bubble program for children for at least 10 years.
Activities include a story about bubbles and a coloring page. Rumschlag also tells children how some animals and insects use bubbles.
“Some of the aquatic ones use them to breathe. They kind of trap an air bubble underneath the water,” she said.
Spittlebugs, also known as froghoppers, make white foam bubbles on plants. The developing nymphs use the foam for protection because predators can’t see the insect for the bubbles.
The foam is also a good insulator against cold and heat.
Rumschlag said betta fish blow bubbles, too, and make a bubble nest.
“They show it to the female, and if she likes it, then they mate and put the eggs in there,” she said.
But the highlight of the program is the chance to actually blow some bubbles, she noted. Rumschlag makes her own bubble solution using 4½ cups water, 1/2 cup hand dishwashing soap and 1/2 cup corn syrup or glycerine.
Then gently stir the mixture and leave it in an open container.
“Bubbles seem to work better with age,” said Rumschlag, who recommends using Joy dishwashing soap.
“And you don’t want to shake the bubble solution. People always want to shake it. That just makes it worse,” she said.
Rumschlag offered some other tips for blowing bubbles:
- If you get a lot of small bubbles instead of one big one, you are probably blowing too hard or you have the bubble wand too close to your mouth.
- Finish your bubble with a quick twist of your wrist to seal it.
- Prepare your bubble solution two to three days in advance. Save any extra bubble solution to use later.
- Make sure your bubble maker and anything your bubble may touch is wet.
- Let the bubble maker sit in the bubble solution for a few seconds. Don’t slosh it around the solution — this creates suds and foam.
- Look for cool humid days, shady areas.
Rumschlag has collected all kinds of wands, both big and small, for the children to use for bubble blowing. She said she’s also going to try making a really big bubble using a hula hoop for the wand and a child’s wading pool for holding the soap bubble mixture.
“It’s just all fun,” she said. “We make them and we have fun playing. And if they happen to eat it, it’s just soap and corn syrup.”
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