Hi ALl...Having just re-discovered fountain pens again and of course, trying all the inks.......Last week received Heart of Darkness...filled up a NEW Sonnet extra-fine point fountain pen....WOW....SMOOTH...SMOOTH....I cannot beleive how THIS pen GLIDES across plain old copy paper....smoothest writing combination to date.....the color is REALLY BLACK....without the chalky light undertones I have sometimes found using Old Manhattan Black and Polar Black....dries VERY fast to RICH DARK, DARK BLACK with NO feathering and NO Nib Creep which is just what I need at work.....THIS combination is a KEEPER......

Pete

They kind of shy away from claiming its bulletproof. Have you test it out?

Who has shied away from calling it bulletproof? The label says "eternal" and the Noodler's website calls it bulletproof, as does Pendemonium and Swisher.

That said, I don't have it and have not tested it.

I have it and while I haven't gone the whole way with alcohol etc, with a simple water test its more "permanent" than Fisher Space pen ink.

There was no sign of running, or streaking when I wet the sample I had and let it soak for 5 minutes.

I'd bet combined with the comments above (Eternal, bullet proof etc.) that this just as good as the others.