Physicists make the perfect soap mix recipe for blowing giant bubbles
Physicists have crafted the perfect recipe for the mixture of soap to blow giant bubbles, and the secret ingredient is a food additive called & # 39; guar powder & # 39 ;.
Seeking to discover how soap films fifty times thinner than human hair can form bubbles that extend more than 10 feet long, the team tested different mixtures in the laboratory.
They discovered that polymers, long molecules found in substances such as guar dust, strengthen the bubbles as their chains become entangled and help resist bursting.
However, the findings are not only useful for bubble blowers, as they could help improve the flow of oil through pipelines and the elimination of foam pollution from rivers.
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Physicists have crafted the perfect recipe for the mixture of soap to blow giant bubbles, and the secret ingredient is a food additive called & # 39; guar powder & # 39 ;. In the image, researchers blow huge bubbles on the lawn of the Emory University campus in Atlanta, Georgia.
WHAT IS GUAR POWDER?
Guar powder is a food additive.
It is used to thicken food or as a source of fiber.
For example, it can be added to baked goods to improve dough, or ice cream to generate smaller ice crystals and, therefore, a softer texture.
It is derived from the guar plant, which is also known as the Lond bean.
The plant is grown mainly in northwestern India and Pakistan, although crops are also grown in the plains of Texas, in the United States.
In the photo, a guar plant
"This study definitely puts fun in fundamental science," said article author and physicist Justin Burton of Emory University in Atlanta, Georgia.
Professor Burton and his colleagues study the so-called & # 39; fluid dynamics & # 39;: the flow of liquids and gases.
"The processes of fluid dynamics are visually beautiful and are everywhere on our planet, from the formation and rupture of bubbles to the aerodynamics of airplanes and the overturning of the depths of the world's oceans," said Professor Burton.
The physicist was inspired to study bubbles after seeing street performers blowing huge using a solution of soap and thick cotton threads.
& # 39; These bubbles were about the diameter of a hula hoop and were as long as a car. They were also beautiful, with color changes from red to green to bluish tones on their surface & # 39; & # 39 ;, he said.
Iridescent, rainbow-shaped colors that may appear in bubbles are the result of the thickness of the soap film near the wavelength of light, about a thousandth of a millimeter, or a fiftieth part of the thickness of a hair human.
This fact made the physicist wonder how such a thin film of liquid could remain intact at distances greater than 10 feet (3 meters), so he and his colleagues set out to investigate in the laboratory.
"Basically we start blowing bubbles and blowing them up, and we record the speed and dynamics of that process," Professor Burton explained.
"Focusing on a fluid in its most violent moments can tell you a lot about its underlying physics," he added.
The researchers tested bubble mix recipes they found in the Soap bubble wiki – an open source project that aims to help the so-called & # 39; bubblers & # 39; to explode the perfect bubble by separating the & # 39; made from folklore & # 39; around the recipes and ingredients of the soap mixture.
The team noted that many of the recipes on the wiki generally included a polymer in addition to water and dishwashing liquid.
Polymers are substances formed by long chains of repetitive molecules.
The most commonly recommended polymers for making a bubble mixture include natural guar, which is used as a thickener or fiber additive in certain foods, and polyethylene glycol (PEO), which is used as a lubricant in some medications.
For each soap mixture they investigated, the researchers threw infrared light through the resulting bubble film to measure its thickness.
The team also determined the molecular weights of the different polymers used by each recipe and tested to what extent each liquid could be stretched by dropping drops from a nozzle and observing the thread of liquid that was between the drop and the nozzle.
Together, the findings revealed that polymers were key to making giant bubbles, with their long filaments that allowed the bubbles to stretch without exploding.
For each soap mixture they investigated, the researchers threw infrared light through the resulting bubble film to measure its thickness, as shown in the image
"The polymer strands get tangled up, something like a hairball, forming longer strands that don't want to separate," Professor Burton explained.
"In the right combination, a polymer allows a soap film to reach a" sweet spot "that is viscous but also elastic, but not so elastic that it breaks."
The researchers also discovered that the use of polymers of different molecular lengths, as can naturally form when, for example, PEO is allowed to degrade over time, can further strengthen the soap film.
"Polymers of different sizes become even more entangled than single-size polymers, strengthening the elasticity of the film," explained Professor Burton.
"That is a discovery of fundamental physics," he added.
The team also determined the molecular weights of the different polymers used by each recipe and tested to what extent each liquid could be stretched by dropping drops from a nozzle and observing the liquid thread between the drop and the nozzle, as shown in the image .
According to the researchers, developing a better understanding of how fluids and thin films respond to stress could lead to a variety of applications, such as helping to ensure that oil flows smoothly through pipes.
"As with all fundamental research, you must follow your instincts and your heart," said Professor Burton.
"Sometimes your bubble explodes, but in this case, we discover something interesting."
The full findings of the study were published in the journal. Physical fluid check.
HOW TO BLOW THE BEST BUBBLES
Physicist Justin Burton of Emory University in Atlanta, Georgia, has recommended the following recipe for blowing giant soap bubbles.
- 2 pints of water;
- 3 tablespoons Dawn professional detergent;
- 1/2 of a heaped teaspoon of guar powder;
- 3 tablespoons isopropyl alcohol;
- 1/2 of a teaspoon of baking powder.
Mix the guar powder with the alcohol and stir until there are no lumps.
Combine the alcohol / guar suspension with water and mix gently for 10 minutes. Let it rest a little so that the guar hydrates. Then mix again. The water should thicken a little, like a thin soup or jelly not curdled.
Add the baking powder and stir.
Add the professional Dawn detergent and stir gently to prevent the mixture from foaming.
Dip a giant bubble wand with a fibrous thread in the mixture until it is completely submerged and slowly pull the thread.
Shake the wand slowly or blow on it to create giant soap bubbles.
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