Why Toothpaste does not mix?
Most toothpaste is like a gel, gel is considered a solid even
though it can easily be mishaped. they insert toothpaste often in
patterns, and that's how it comes out when you squeeze it. I'm sure
if you took 2 tubes of different color toothpaste and put it into a
bowl then mixed it with a spoon, it would mix; but your question is
very similar to something like, "When you hold your toothpaste
upside down does the toothpaste come out". It doesn't mix in the
tube, but you can mix toothpaste together.