Dipping in beet juice gives a beautiful range of colors. I lay my sheets out in my gravel driveway and dip my fingers into a cup of (undiluted) beet juice, then shake my hand over the sheets. Some get MORE drippy marks and some LESS... I just keep going until I like what I see.
Then I leave them out to dry in the sun, iron, and i'm ready to tear! The juice from a can of beets keeps in the fridge for a long time and is PLENTY to prepare many sheets for future projects.
I have used it on copy paper, cheap parchment paper from the Dollar Store, and nicer lightweight drawing paper (gray gives an AMAZING result), music paper, book pages, and watercolor paper.