How come no matter what colour the shampoo/soap is the foam is always white?

For once in my life I was to have red foam. Cmon Science, step up your game.



Most Helpful Girl

  • By little kid shampoo. Surely smart people learned how to do that for the children. I mean, there is purple ketchup!

    • i used to buy shampoo that smells like butte gum. Best shampoo ever. But I have never seen purple ketchup haha. You need to ship some over here :D

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    • I really like oven baked chicken enchiladas loaded with cheese :D. Id love to hear that recipe some time if you dont mind sharing. I am not a big fan of chicken wings but my favorite food has to be pizza, especially quattro formaggi (spelling might be incorrect). If i am cooking I have a special recipe from my mom. I dice pork meat and mix it with mushrooms yoghurt cheese spread and red wine inside a clay pot. You can also have a sip of the wine but I dont like how alcohol tastes lol. Since the pot is made out of clay it takes up to 3 hours to cook but its well worth it.

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Most Helpful Guy

  • The color of the shampoo in the bottle is the color of the light that is not absorbed by the shampoo. But foam is made of lots of tiny bubbles, and there is only a thin film of water and shampoo around the bubbles. There isn't much shampoo in the film, it's almost all water. The foam appears white because the bubbles are reflecting all colors about equally. There isn't enough shampoo in the foam to give any color to the foam.


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What Girls Said 5

What Guys Said 3

  • I know this has already been answered, but some kinds of temporary hair dyes (the kind you apply to wet hair) can have coloured foam, and likewise if you dye it permanently, you might colour the foam of your shampoo a bit when you rinse it.

  • It is basically the same mechanism that makes clouds white. The object (water droplets or foam bubbles) are big compared to the wavelength (of light). Mie scattering

    The other effect Rayleigh scattering, wavelength small compared to object (molecule) can be observed in the sky or water. That's why the sky is blue and red light does not penetrate water as far as blue light. red light wavelength is longer; less energetic

  • I think I got the answer your looking for.. It just is.

    • Imagine Newtons frustration if he asked "Why does the apple fall?" and people said "It just does"

    • This is true dammit we need colored soap.