One final word about the water resistance of Scabiosa - it does a pretty good job of clinging to skin. This took a few washes to get completely off.
Rohrer and Klingner Scabiosa is a wonderful ink that I will not hesitate to recommend. It is the only purple iron-gall ink that I know of, it behaves admirably on all paper, and it is lovely to write with. If you like dusky purple inks like J.Herbin Poussiere de Lune or Diamine Damson, or you like your ink to have better staying power than the average ink, be sure to check out Scabiosa.
Review notes: The widest lines were made with two Pilot Parallel calligraphy pens: one with a steel 6.0mm nib and the other with a steel 3.8mm nib. The medium lines were made with a Lamy Joy Safari with a 1.9mm steel calligraphy nib. The narrow lines were created with a Visconti Homo Sapiens with an EF palladium nib. The paper is Rhodia 80 gsm from a Rhodia Bloc No. 18. The featured script is Fractur.