30ml bottle of Blackstone Ink's waterproof, permanent ink - "Barrister Blue-Black."
This ink has been designed for use in fountain pens and is perfectly safe, however due to the waterproof and permanent nature of the ink, it can be difficult to remove from pens if allowed to dry out in the pen. It may also permanently stain some types of plastic pens, particularly transparent plastic pens.
Blackstone Barrister Blue-Black is a well behaved blue waterproof, permanent fountain pen ink made in Australia by Blackstone Ink. Barrister Blue is 100% waterproof and is unaffected by complete immersion in water. It is fade resistant and highly resistive to bleach, alcohol and mild acids.