system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens to the stuff used to color soap when we lather it up?
gpt
Pigments in soap are very weak and intended to not stick around long. When you get all lathered up, you're increasing the surface area of the soap by thousands and thousands of times due to all the bubbles. Because there is now a huge amount of surface with different optical properties, you are no longer able to see the dye. The dye is intended to be visible only when looking through quite a bit of the soap.