system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does Paper get transparent if you rub it with fat?
gpt
This is because when fat is absorbed into the paper's pores, the grease-stained part of the paper—which is normally white due to the scattering of light that shines through it—allows less scattering, and the light passes through it, appearing darker in color and translucent.