Dear Mr. Scienceman... | Seventh Generation
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Dear Mr. Scienceman...

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Author: scienceman

Dear Scienceman,

Where do bubbles come from?

-- C.L., Foam, MT

Dear Cheryl:

To make a bubble you need a material that, when spread in a thin film, won't pull itself into a tiny drop (like water pulling itself into a bead on a waxed surface). This tendency to pull into a drop is called surface tension, and water has a high surface tension.

Adding a surfactant (SURFaceACTive AgeNT) to water reduces the surface tension so a bubble can form without collapsing itself into a drop. Reducing the surface tension of water also allows the water to mix with oil and grease, which is why surfactants are used for cleaning!

I hope this answer was helpful!