Eli5: With all the colors in shampoo, Why is the foam always white?

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Eli5: With all the colors in shampoo, Why is the foam always white?

In: Biology

The bubbles are very thin and most shampoos don’t have strong enough pigment that would be noticeable in that thin layers. The individual bubbles turn effectively mostly transparent with only small amounts of each color being reflected from them. When there’s lots of the bubbles, those small amounts of each color add up and that results in white.

There are some shampoos which have colored foam tho. (stronger pigment) I recently bought a random shampoo and was kinda surprised when I had blue foam on my head for probably the first time in my life instead of the regular white.

The bubbles reflect light on so many different faces of the bubbles that it will always appear white to you cause that’s the only way your eyes can process it.