How do the properties of lipids relate to grease spots on paper?

Question

I had a lab about lipids where my class just rubbed olive oil on a brown piece of paper. I do know it has something to do with filling the gaps in the papers leaving a translucent surface, but how?

Answer 1

I think the reason the paper gets translucent is not about the
chemical but rather the physical property of the oil - its
index of refraction. If it is the same as the paper fibers,
then no scattering of light. If it is different
(air vs paper: different) then mucho scattering.