Alison, an online friend, said she intentionally pour coffee on a piece of her work. That started a conversation about different things we would use to color paper. I used tea and raspberry drink mix (sugar free). It was one of those little packs you put directly into a bottle of water. I tried dripping it and painting with it. I use watercolor paper, craft colored card stock as well as a piece of thinner paper I had. The bottom left result was done by dropping a little on the thin paper and then blowing the drip with a straw. I like the look of that one a lot.
Be advised... you may go to work the next day with red fingers.