Here are some tests I did today for my backgrounds with the ink flowing in. Being the after effects noob I am, I'm kind of happy I managed to pull this off :p The first four ink spreads are taken from the awesome video posted below. I wanted to try out different kind of ways ink can spread and see what kind of look/ effect it gives.
The last video uses a ink dropped in water video- a little too liquidy for my taste, but what I DO like is how the ink seems to bleed in more color instead of the background emerging from blackness, which is what the first 4 tests do. Not sure how i did that, but I was just playing around and it happened.
I'm planning on filming my own ink on water videos so I can better control how I want the ink to work. I love the look of ink spreading on paper more than ink in water, so I decided I'm going to go with that look.