To achieve this effect, I dipped a string into watered down acrylic paint, placed it looped all around between two sheets of paper, placed a book on top for weight, and simply pulled the string from between the paper and book! It was pretty fun to try out!!
Thank you so kindly! It was one of my first tries at this technique. It does take some finesse, but a lot of it is up to chance too! So it's always interesting to see how it comes out when you take the papers apart!