Parkpop Purple fountain pen ink made by P.W. Akkerman pen store in The Hague.
This purple ink has good shading, and no sheen.
Originally made to celebrate their 100th anniversary, this ink comes in a vintage-style bottle with a narrow neck with a marble stopper, to create a well at the top to aid in filling pens.
The Parkpop festival is a free music festival held annually on the last Sunday of June in The Hague. Ackerman