Why are soap bubbles always white?

soap_bubbles_close_up

Bars of soap have almost disappeared from the grocery store shelf. You can find them in the boutiques with scented oils, etc. The old Lava soap and Goop you can still get at the auto parts stores.   Therefore, bar soap has just about been replaced with liquid body soaps in a variety of flavors and colors.

Dish soap also comes in many colors, smells and strengths as well as laundry soap.

However, with all of these colors, once you put it on and lather it up, it is always white. Why?

Here is a response provided on answers.com:

“The bubbles appear clear because they are composed of a very thin layer of soapy water only a few molecules thick. The dyes in bubble film are too sparse to have much direct effect on the light passing through it, this results in the bubbles appearing clear. Actually if you look closely at the bubbles, you will see different colors moving across the surface of the bubbles, these colors are the result of the light being refracted by the water and chemicals in the water.”

Makes some kind of since doesn’t it?   Let us look at the definitions of what we need here. Definition of white: of the color of milk or fresh snow, due to the reflection of most wavelengths of visible light; the opposite of black. Definition of black: of the very darkest color owing to the absence of or complete absorption of light; the opposite of white.

So it doesn’t really explain why it is white.   Soap was usually made from animal fats and lye and the chemical reaction to them. White was the color and dirt was brown or black so it became ingrained into our psyche that white is clean. Scientists have found other uses for these substances (mainly in our diet) which raised the costs so the chemical companies (Proctor and Gamble, etc) went to liquid soaps.

So the question is what chemicals do they put into the soaps to give them the colors and then what needs to be added so that it produces white bubbles when hydrated (water added to it).

So the exception to the rule. For the first time, I used AXE brand Phoenix 2-in-1 Shampoo/Conditioner. It came out of the bottle dark blue and even had blue bubbles as I scrubbed my head. So the question is what chemicals did they put in to keep it blue on my head.

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