I had some peony blooms from a wedding a couple of weeks ago and decided to see if they would produce an ink. I added a bit of alum as a mordant as I wasn't sure if their coloration was tannin based like the examples in the lesson. I also added a small amount of gum arabic. Surprisingly, this ink seems water resistant. 

Would love to test and find out if it is lightfast. *I have previously made black walnut ink and it is incredibly lightfast (but not water resistant).