30ml bottle of Blackstone Ink's waterproof, permanent ink - "Barrister 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 Black is a well behaved, pure black, waterproof, permanent fountain pen ink made in Australia by Blackstone Ink. Barrister Black is 100% waterproof and is unaffected by complete immersion in water. It is fade resistant and highly resistive to bleach, alcohol and mild acids.
Barrister Black is a nano carbon ink similar to Sailor Kiwa Guro Nano Black and Platinum Carbon Black. Barrister Black is made with sub-micron sized carbon particles instead of the usual soluble dyes. These nano carbon particles are so small that they can easily pass through fountain pen feeds and are treated with a special soluble polymer to overcome their natural attraction to each other.