Pelikan Fount India is a document-proof black ink for fountain pens. It is certified to be completely waterproof, and it will not fade under direct sunlight.
Pelikan Fount India is a pigment-based ink. It could be used (and will retain its document-proof properties) on any surface, not only paper.
Warning: this ink is suitable for fountain pens, but you will have to clean your pen regularly and never allow this ink to dry out inside your pen.
At Scribe Market we would recommend to set one inexpensive and easy to replace pen for use exclusively with this ink and flush it between every refill.