system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does shaving gel go from a blue viscous liquid to a foamy thick liquid?
gpt
The blue liquid inside the can is very thick and full of little bubbles (like a chocolate mousse, but much tinier).
The bubbly liquid is packed into the can really tightly, there isn't a lot of space, so the bubbles get squished down smaller to make room. When the liquid comes back out of the can, the bubbles have lots of space again, so they're free to stretch back out to their normal size. The bubbles are colourless, so as they grow, they make the colour of the liquid look fainter and fainter.