Iron nut-gall blue/black ink made by P.W. Akkerman pen store in The Hague.

Originally made to celebrate their 100th anniversary, this ink comes in a vintage-style bottle with a narrow neck with a marble stopper, to create a well at the top to aid in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.

Please note: this ink is dark blue when wet, and darkens to a grey-black as it dries. This is permanent and waterproof.

Ackerman